To begin this rather lengthy chapter which attempts to detail all aspects of oleander culture, we would like to offer a thought from Kewpie Gaido about her beloved oleanders. "They are so beautiful," she said, "and with just a little care they do well and show their appreciation by doing better than they had originally been known t

All the flowers of all the tomorrows

All in the seeds of today and yesterday.

Chinese proverb

Propagation

Seeds

Seed pods should be collected in the United States in warm climate zones during late December and early January. In the tropics they ripen throughout the year but are most abundant from winter to early spring. Keep the pod in a paper or plastic bag or container until it splits open to reveal the seeds. Oleander seeds are highly viable and germination can be nearly 100% with many cultivars. Seeds are very small and thin, usually not longer than 1/4 to 1/2 inch or even smaller, and have a coma at one end.

Planting Media for Seeds

Always use a sterilized planting medium that is loose and provides good drainage but is sufficiently moisture retentive. There are a number of commercial mixhtfes that are excellent. These are basically lightweight "soilless" mixes composed Pomarily of finely ground spaghnum peat moss mixed with perlite (occasionally

Page 63

vermiculite) and, in the best products, a surfactant, or wetting agent. Some formulations also contain a "starter charge" of diluted, water soluble nutrients, not strong enough to burn but sufficient to get the germinating seedlings off to a good start.

Planting the Seeds

Moisten planting media thoroughly prior to sowing the seeds. It is helpful to level the media in pots or trays with a flat object such as a small block of wood. This assures uniform water distribution and makes it easier to cover the seeds evenly. After placing the seeds on the media cover them very lightly, no more than " inch deep, preferably % inch. We refer to this as the "salt and pepper treatment" and will often sift our planting media through a fine mesh in order to provide the finest covering material. After covering the seeds tamp the soil with the same block of wood used for leveling. This will assure good soil contact with the seed and promote higher germination.

In our plumeria handbook we mentioned planting seeds vertically with only the papery wing exposed above the soil line. Oleander seeds may also be planted in this manner by inserting . the tip of the seed into the media so that only the coma (tuft of hairs at one end) remains above the soil level.

Watering Seeds and Seedlings

Bottom watering is always preferred whenever possible but since oleander seeds are not minute and dustlike, a watering can with a fine rose to prevent the media from washing away will do very well. Keep the soil damp, not wet, until the seeds germinate. Overwatering and planting seeds too close together can lead to damp-off, a fungus that can destroy a crop of seedlings in an amazingly short time. There are commercial fungicides one can apply to

Mrs. Willard Cooke

Page 64

prevent or retard damp-off but it is always best not to plant seeds too closely and never overwater.

Germination

Success with seeds depends on a number of factors but these are not complicated. Ivlost importantly, seeds must be fresh. Oleander seeds do have a very high viability, as mentioned above, but they must be sown within a few months of harvesting or viability drops off considerably. Year old seeds are generally no longer viable. Soil temperature is also critical. A cold, damp soil is more likely to cause seeds to rot than allow them to germinate. Either plant in warm weather, or supply bottom heat with a heating mat or heat coils kept at a temperature of 75 to 80 degrees. Germination usually takes place in ten to twelve days and initial growth is fairly rapid. As a further indication of the viability of oleander seeds, we recount Dr. Parsons' experience with seed that was supplied by Elizabeth Head from the finest cultivars in Galveston and irradiated at Texas A&M University. Dr. Parsons said, "Anyway, I had them irradiated and they [Texas A&M] sent me the seed back. I don't know if You've seen oleander seed, they look like cotton. And I said, these damned things are not going to come up and the next thing I know they're as thick as hair on a dog's back and I end up with 600 seedlings!"

Mrs. Willard Cooke

Care of Seedlings After Germination

As seedlings germinate, apply a dilute solution (usually 1/4 strength) of a balanced water soluble fertilizer such as 20-20-20. The first set of leaves are called

Page 65

cotyledons, or "seed leaves," and are generally different in appearance from the "true leaves." When the first true leaves appear, increase the fertilizer to half-strength. When seedlings are about 3 to 4 inches high it is time to transplant them into individual pots.

Pros and Cons of Propagation by Seed

One of the greatest pleasures of gardening is raising a plant from seed and following its growth and development through to the moment it flowers. An important benefit of planting oleanders from seed is that one can, with very little expense, raise a great number of plants and with reasonable certainty, depending on the quality of the original cross, find a new color, shape, form or fragrance in a large batch of seedlings. In addition, one may be fortunate to develop a plant with greater hardiness or disease resistance. It must be kept in mind, however, that most seedlings will be inferior to the original parent plants and should be destroyed after evaluation. Propagating from cuttings assures that the new plant will be identical to the original but only with seeds can we discover something new.

An Additional Note on Seedlings

In general, it takes from one to two years for an oleander to flower from seed. After planting seeds in spring, pinch back seedlings in late summer or early fall to encourage branching. If not pinched out many seedlings tend to grow straight up.

Mrs. Runge

Page 66

Most plants, if started from seed in April or May, will go through one growing season and flower in late spring of the following year.

Cuttings

Oleander cuttings are very easy to root, even for beginners. Cuttings should be taken in early spring when plants are growing vigorously as they will root most quickly at that time. Also, unless one has access to a greenhouse with a cooling system, hot summer temperatures elevate bacterial metabolism in cuttings so they will tend to rot before they can root. Donald J. Moore, former Superintendent of the Botanical Gardens in Bermuda, mentioned that cuttings there are best rooted in nursery beds or even planted directly into the ground where they are to grow. This was also our experience in the tropical climate of southern India. There we developed a rooting media of coir dust, the granular residue of the coconut husk that remains after the fiber has been extracted, mixed with sharp sand. We placed cuttings in the shade of a mango tree, out of the wind, and consistantly had close to 100% rooting. Kewpie Gaido tells the story of her father's experience with an oleander. He needed to stake a special plant he had just acquired and since there were oleanders all around, cut a long straight oleander stem for a support. In short, his plant died and the oleander rooted!

In his experience with variegated oleanders. Dr. Jerry Parsons discovered that, like many other variegated plants, they were more difficult to root whether the variegation occured in the flowers or the leaves. (He also found this to be true of variegated plants propagated by tissue culture.)

Type and Size of Cuttings

Tip cuttings make the most attractive plants so always select a branched cutting and you will have a nicely shaped plant almost immediately. If the tip cutting is not branched, the top may be pinched back as soon as roots have formed and the axillary buds will quickly produce shoots creating a well balanced shape. The best wood is at least a year old and anywhere from % to % of an inch in diameter. Cuttings up to 24 inches in length may be rooted either in water or in a soil media if they are taken at the proper time when in an active growth stage. Many gardeners in tropical climates also use the suckers that form at the base of plants.

Rooting Media for Cuttings

As we have found with phimerias, one of the best mediums for rooting oleanders is coarse perlite, or a mixture of three parts coarse perlite and one part peat "loss. This assures good drainage and aeration. In recent years, Elizabeth Head of fhe Oleander Society has made numerous tests of rooting media and has also conduded that the highest rooting percentage has been with coarse perlite. As we observed with plumerias, the newly emerging roots attach themselves to the perlite granules and form a mass that holds together well during transplanting. We have

Page 67

also used sharp sand (builder's sand or concrete sand) with excellent results. Do not use mortar sand as it has none of the sharp particles of silica that improve aeration and drainage. Some growers mix a very small quantity of peat moss into the sand (not more than 5 or 10%) for added moisture retention.

Rooting Cuttings in Media

This is the simplest and most effective way to root large or small quantities of oleander cuttings. Keep media moist but not wet, and do not allow it to dry out at any time during the rooting period. As soon as you see new leaves emerging, begin fertilizing with a water soluble fertilizer such as the 20-20-20 formula recommended for seedlings diluted to '4 strength. Resist the temptation to use full strength fertilizer as it will burn the newly emerging roots. Rooted cuttings will grow very rapidly with supplemental fertilizing. Transplanting may be done at almost any stage when new growth is evident.

I asked the Turners, who have rooted thousands upon thousands of cuttings, what problems, if any, they had experienced. Ted Sr. offered some illuminating advice. Having had some losses due to a fungus which especially affected the petites, they began dipping the cuttings in a mixture of two tablespoons Captan per gallon of water before placing them in the rooting media. "\ prefer getting cuttings in between rains and not right after a rain when they're full of moisture," he stated. "We dip them, just drench them [in the Captan mix] and then let them dry almost completely. And then I use Rootone. We stick the base of the cutting and up about Vi inch of stem into the Rootone. I still use Rootone because my greenhouse is not a propagation house so I have more trouble now than I used to. We used to have mist and we could just put them in any way we wanted to and they would root. But I have a mixture, you saw what I have, there's every kind of plant imaginable in that greenhouse, so I have more fungus in there from having to use too much moisture on some of the tropicals and oleanders don't like that. They like a hot dry house where most of the tropical plants like a humid greenhouse." It is important to note that if you have a greenhouse without mist, take cuttings of hardened wood. If you have a mist system, take transitional (half hardened) wood rather than the soft, green wood of new growth.

Inserting Cuttings in Media

Make a cut, using sharp, sterile pruners or pruning knife, at the base of the stem just below a node. Cut on a 45-degree angle to provide a larger surface area for roots to form. Moisten the cutting, shake off any excess water and then apply a rooting hormone. (It is a good idea to put a small quantity of rooting hormone into a separate container so as not to contaminate the remainder with moisture.) Bob Newding shares a special technique he uses to encourage more roots. At a tangential angle to the stem, make a cut just under the cambium 1 to P/2 inches up from the base of the cutting. Open the flap slightly and with the knife blade insert some Rootone or other rooting hormone under the flap. This will encourage roots to form throughout the area of the cut and not just at the nodes immediately above the base of the

Page 68

cutting. The extra work is worth the effort, especially on rare plants or those that have proven somewhat difficult to root. Before inserting the cutting into the media, make a hole with a stick or another cutting of equal size to the required depth so that when you insert the cutting the rooting hormone remains undisturbed. Larger cuttings should be inserted 3 to 4 inches or more into the media so they will be supported, smaller cuttings up to 2 or 3 inches. It is helpful to place them at a 45 degree angle as this allows easier transport of nutrients to the tip of the cutting during the rooting process. Water-soluble rooting hormones such as Dip 'N Gro are commercially available, very easy to use, and are absorbed more readily by the tissues of the cutting. (Be sure to use distilled water when preparing a solution.) We have had excellent results with rooting many types of plants with Dip 'N Gro but have not tried it on oleanders as yet. We have no reports of anyone using water-soluble rooting hormones to date and would appreciate receiving any information for inclusion in future editions of the handbook.

Turner's Tickled Pink™

Sun/Shade Requirements for Rooting Cuttings

Bright shade, filtered light, a north-facing windowsill or a bright room out of direct sun all work well for rooting cuttings. The most important thing is to keep them out of the wind and cold.

Transplanting Cuttings Rooted in Media

The roots of cuttings rooted in sharp sand or other media are strong and transplanting is easily accomplished using normal caution and standard techniques.

Page 69

Ted Turner, Sr. with Turner's Carnival™

Comparison of Turner's Carnival™ (left) and Turner's Tickled Pink™ (right)

Page 70

Extra care may be necessary when lifting cuttings from sand/ however, as the weight of the sand may cause some breakage.

Rooting Cuttings in Water

Several members of the Oleander Society find this to be the easiest method of rooting cuttings. The only drawback is that roots formed in water are very brittle and have a tendency to break easily when transplanted. Choose a branched cutting from 10 to 18 inches long and remove all but the new terminal leaves. It is important to check that the plant is vigorous and healthy and free of insects and disease, especially bacterial gall. Use a non-metallic container such as glass or plastic and check the water level regularly, being sure not to allow algae to develop. Depending on the variety cuttings will root in five to twelve days but if taken too early in the spring may take up to three weeks. Some growers suggest adding a very minute quantity of fertilizer and rooting hormone to the water; others feel this is unnecessary. Cuttings taken with a "heel" will assure an even higher percentage of rooting in water (or media) but the extra work is hardly warranted since the rooting percentage will almost always be over 90%.

We have read published recommendations for rooting large stems 4 to 6 feet tall in water. This is erroneous information and will rarely succeed. Biologist Bob Newding explains why: "The reason you cannot do it is that the plant will rot before it will root. You are looking at cells that are trying to metabolize without any roots and they generate heat. The bacteria grows very quickly in warm water — because you need warm conditions to do it — and the darn things rot."

Transplanting Cuttings Rooted in Water

As mentioned above, the roots of cuttings rooted in water are extremely brittle and unless handled with the greatest care will snap off easily. Transplant rooted cuttings when approximately four to six roots have emerged using the following technique. Select the proper size container consistent with the size of the cutting. Using a very light, highly organic potting soil, fill the container so that the cutting will be at the proper depth, mounding the soil slightly in the center. Lift the cutting from the water and place it carefully on top of the potting soil in the container. Do not push the roots into the soil but gently spread them on top of the mound. Slowly fill the container with more soil to the correct level. Do not pack the soil around the roots! Water gently and the soil will fill the interstices, eliminating air pockets. If you are concerned about breaking roots, allow the cutting to remain in the container until it is filled with roots. At this point the roots will be hardened off, are no longer so brittle and can easily be transplanted.

Air Layering

Air layering is an excellent technique for propagating difficult-to-root plants Plant. Most of the time oleanders root so easily in water or media, and so much more ^pidly, that air layering is not required. There are occasions, however, when air

Page 71

layering is recommended. Rare and one-of-a-kind plants, or particularly challenging plants, are best air-layered to be absolutely sure of success. It is also the best method when you wish to start a tree-form specimen. For those seeking instant gratification, choose a branch with latent buds and you will have a blooming plant in a matter of weeks.

For a tree-form plant, make the layering at a point on a branch so that the portion above the layering (that will be the new plant after roots form) has the desired length and girth. For a ready-made bush shape, make the layering just below a section where there are already several branches. To make the layering, cut upwards into the stem at a 45-degree angle with a sharp, sterile knife or blade, stopping about one third of the way through. Place a tiny pebble or gravel chip in the cut to keep it from closing and healing over. A powdered or liquid rooting hormone may be applied. Place a double handful of damp sphagnum moss over the entire area, cover with plastic or plastic wrap, and secure at both ends. While you work support the upper portion of the branch so that it does not bend or break at the point of the cut. Sufficient moisture should be retained by the plastic during the time necessary for rooting but protection from hot sun and wind should be provided. (There are numerous "How-To" books available that illustrate all types of layering.)

Ground Layering

Ground layering is another technique for rooting large stems to be trained into tree-forms. Simply bend a stem of the desired height and, as near the ground as possible, make a 45-degree incision on the underside upwards into the stem about one-third of the way. As with air layering, the stem still receives nutrients from the main plant and one is assured of rooting. Again, keep the cut open by inserting a very small stone chip or pebble so that the stem cannot heal around the cut. Use a container filled with a porous rooting mixture as described above for cuttings and be certain the bottom of the stem (where you have made the cut) is fully in contact with the soil. This is not quite as easy as it seems when one is handling large stems and it is sometimes necessary to raise the pot of rooting medium off the ground. Place a heavy stone on top of the container so the stem is held firmly in place and cannot spring up. Monitor the container carefully as it is important that the soil should not dry out.

Grafting

The Turners have grafted the petite oleanders onto 'Hardy Red' with excellent success, creating a tree-form plant with the compact, long-blooming head of the petites. They allowed five feet of trunk and since the head was small, the tree did not require staking even in the high winds of the Gulf Coast. One can also create "rainbow" trees by grafting several selected cultivars onto hardy stock.

Ted Sr. commented, "I read an old, old book that said you can graft the Desert Rose [Adenium] onto oleander and the Desert Rose will bloom twice as good. I haven't done it yet but I'm going to do it." Frank Pagen agrees stating: "Adenium spp. can be grafted on a Nerium oleander rootstock to produce profusely flowering plants."

Page 72

There are many types of grafts described by names such as wedge, saddle, side, veneer and cleft, with whip-and-tongue being the most common. The plant with the desirable flowers, fruits and foliage that is to become the new "top" is called the scion. The plant that will provide the root system is called the stock. The success of the graft requires that the cambium (the tissue just beneath the bark) of the scion and the stock is joined so that it eventually grows together. This is accomplished by assuring that the stock and scion are the same thickness. Gardeners who think nothing of sticking a hundred cuttings in an hour sometimes hesitate to try grafting, perhaps thinking it too difficult and unpredictable. It is true that some people seem to have a certain "touch" but with just a little practice anyone can achieve success. There are many books containing illustrations of different types of grafts that are helpful to the beginner and we encourage everyone to give it a try. Fascinating combinations, such as the "rainbow" tree mentioned above, can only be accomplished by grafting.

Soil Preparation for Planting in the Ground

In discussions with growers and horticulturists over the years, the consensus seems to be that oleanders will grow in almost anything! As Ted Turner, Sr. remarked, "They grow in oyster shell and sand, Galveston proves that hands down." Having been involved with composting and soils for so much of our lives, however, we can't resist offering some general suggestions to encourage the best performance from your oleanders.

Oleanders grow much better in sandy soils than clay soils. If you have a clay soil, amend it with ample amounts of organic matter, preferably compost. Well-decomposed bark, composted hulls or leaf mold are also very useful. Do not use fresh bark or any other raw organic material as nitrogen "draft" will occur and the nutrients meant for your plants will be ^ed by bacteria to break down the organic

General Pershing

Page 73

matter. The two most important elements plant roots require are oxygen and drainage. All clay soils require flocculation and adding compost or decomposed organic matter to your planting media is the best way to insure this. We also recommend adding organic matter to pure sand and sandy soils. Even though oleanders may be found growing in such soils, the addition of organic matter will aid moisture retention and will help prevent leaching of nutrients.

Any extra effort when preparing a planting hole will pay huge dividends in the future. This is why we recommend digging a hole at least twice or three times as wide as the root ball of the plant, but no deeper.

Sister Agnes

If the first cause of plant mortality is overwatering, the second is usually planting too deep. By carefully measuring the depth of the root ball one can prepare a hole of the proper depth. One of the guidelines we have always used is to plant the root ball an inch or two above ground level to allow for future settling, then cover the surface with a solid three inches of mulch.

A current school of thought suggests that adding any organic matter to the backfill mix creates an interface problem and prevents a plant from adapting to the soil in which it will grow for the remainder of its life — but we don't subscribe to it. Having worked in laterite soils in India, black gumbo soils in Houston, and now the red clay hills of Georgia where even power augers have difficulty penetrating, we have witnessed the struggle of plants in unamended planting media. For the last forty years we have always added approximately one-third compost, well-decayed leaf mold, or other fully decomposed organic matter to our backfill mix and have always had excellent results. The only exception is the unique situation of highlv saline soils. From their experience with salinity in the Gulf Coast area of Texas, the Turners recommend being very careful about adding too much organic material tr

Page 74

such soils as excess salts will be retained instead of leached, thereby causing toxic shock to the plant roots.

It is important to understand that while oleanders will grow in poor soil, they will be at their best in well-drained soil with average fertility. But to balance all this technical information, we should, once again, emphasize how easy it is to grow oleanders. As Dr. Jerry Parsons says, "I tell people, if the highway department can grow them, anybody on earth ought to be able to grow them ... they're tough!"

Planting and Transplanting

Deep in their roots, all flowers keep the light.

Roethke

Basic Guidelines for Transplanting

We'd like to share some basic rules for transplanting that will assure success for first time gardeners as well as experienced hands. Whether you are transplanting seedlings or rooted cuttings, the same rules apply. Before beginning have all your materials ready. Fill pots to appropriate levels with potting soil and have additional potting soil ready for topping up after transplanting. Have water handy and work in the shade, preferably late in the day so plants will have the night to recoup. If that is not possible, then transplant in the early morning while it is cool. To reduce the stress of transplanting we have always advocated the use of Superthrive, a transplant formula with vitamins and hormones, as it has consistently given us excellent results. When I was in my teens I often went with my father to visit his friend and grower Martin Fleischut where I learned many things about plants, but none more important than the fact that the roots of seedlings and cuttings could die in one minute if exposed to heat and wind. I have followed Mr. Fleishut's advice all these years and the moment we prick out a tender seedling or lift a rooted cutting, it goes into its new container immediately, is watered, and set in shade or filtered light where there is no wind.

Planting in the Ground

Oleanders are easily transplanted directly into the ground and quickly form a mass of fibrous roots under the proper conditions. Remember to add a time-release ferrtilizer at the time of planting. In general, oleander roots move laterally rather "an vertically. The exception to this is when they have insufficient water and have to find an additional source of moisture on their own. There have been many instances of oleander roots clogging old clay drainpipes so planting away from drains, sewer lines and septic tank fields is always advisable.

Once again, before removing the plant from its container be certain you have everything in readiness, i.e. prepared backfill mix, water, mulch, etc. On removing

Page 75

the root ball from the container check to be certain there are no encircling roots. If the plant is heavily rootbound the roots will need to be "combed." If encircling roots are very large they should be removed with pruners. Otherwise, like a bad habit, they will continue circling and never change their ways by spreading out or descending into the soil. With the "comb" of your choice, tease the roots down and away so they will spread outward in the hole. Do not cut away too many roots unless a plant is so potbound that there is no alternative. The general guideline should be to disturb the root system as little as possible, keeping plant stress to a minimum. After planting, water in thoroughly to dispel any air pockets in the soil and add transplant vitamin or root stimulator.

There are two basic watering techniques that are effective in getting sufficient water to the root ball. Both are excellent and although we generally prefer the first, we have used the second with equal success. After planting, instead of firming the soil around the root ball, push the end of a garden hose (with just a trickle of water at first) into the soft soil between the edge of the root ball and the edge of the planting hole as deep as it will go. You will soon see the water pulling the soil into and around the rootball. If water comes immediately to the surface, decrease the water pressure and try again in another spot. Move the hose to three sides of the rootball, letting it soak in each area until water begins spilling out. The second method consists of tamping the soil until it is firm, building a berm around the outer area of the root ball and then allowing the hose to trickle on the surface until the berm is filled and the water percolates down. Depending on the size of the hole this may have to be repeated two or three times to insure thorough soaking of the media. The berm may be left in place through the first season as it is useful whenever you need to provide supplemental water.

Mathilde Ferrier

Page 76

Sun/Shade Requirements

The major factor that influences color in oleanders is sunlight. Most oleanders require full sun, or nearly full sun, to be at their best. In shaded locations plants bloom sparsely and will tend to stretch and become leggy in their attempt to get more sun. There are several varieties, however, that will perform well in part sun. Newding mentions that 'Sorrento' will bloom in partially shaded locations. According to the Turners, 'Shari D' will bloom in 50% shade and it doesn't matter whether it is 50% filtered light all day or full sun for half a day. For most varieties the amount of sun has a direct effect on flower production so it is important to provide as much heat and sun as possible for best performance.

Watering Plants in the Ground

The first year after transplanting is the most critical time in an oleander's (and most other plants) development. During this period it is important to provide supplemental watering (especially if rains are irregular) to encourage development of a solid root mass capable of sustaining the plant for years to come. When you water, water deeply to encourage the roots to travel downward. Frequent light waterings encourage feeder roots to remain at the surface with potentially serious consequences if waterings are missed and extended droughts prevail. After the first year, supplemental watering should still be provided during periods of drought. Although established plants will survive drought, additional watering will keep them in a much healthier condition and help maintain flower production.

Humidity

Although we have seen that oleanders are highly adaptable to all kinds of weather conditions, thriving in dry desert air as well as the high humidity of the Texas Gulf Coast, the Turners observe that there is something different about high humidity in a greenhouse and high humidity outdoors. They readily admit they don't really know what the difference is but have observed that when conditions are too damp in the greenhouse, spent oleander blossoms remain on varieties that are normally self-cleaning. This same phenomenon has also been observed in the hot, humid climate of Malaysia.

Fertilizing

Our recommendation for fertilizing oleanders to promote maximum flowering is to use a formula high in phosphorus. We alternate a controlled-release fertilizer with an NPK (N=nitrogen, P=phosphorus, K=potassium) of 5-32-5 with a water-soluble formulation of 9-58-8. The low levels of nitrogen maintain plant health but do not push growth. For basic maintenance of oleanders growing in sand or sandy soils with little or no organic matter, fertilize twice yearly with a controlledrelease fertilizer using a balanced formula such as 13-13-13, alternating with a high

Page 77

phosphorus formula since nutrients tend to leach quickly in light soils. In areas such as Galveston, where soils are already very high in phosphorus, additional amounts will prove detrimental as too much phosphorus binds micronutrients rendering them unavailable to the roots. It is always best to take a soil test to determine the basic nutrient availability, or lack of it, in your soil whether plants are in the ground or in containers.

Timed-release or controlled-release fertilizers are designed to assure a constant supply of nutrients over a given period. However, due to the nature of the timed-release mechanism — the most widely used formulation being a coated prill that releases nutrients through osmotic action based on heat and moisture — the release curve of nutrients is more rapid in hot weather. Under these conditions, nine to twelve month formulas will be expended long before the suggested period for nutrient release. We have found the three to four month formulations to be more effective in warm climate areas with two applications per year, one in early spring and one in summer.

The best technique for fertilizing large established plants is deep root feeding. We recommend the following: For granular, slow-release products make holes approximately 6 to 12 inches deep, spaced 1 to 2 feet apart and placed 1 to 2 feet on either side of the drip line. (The drip line is the area just below the outer branches where rain would fall off the leaves in the greatest concentration. It is also the area where the most feeder roots are located.) The holes can be made with a rock bar or pick, or even a % to 1 inch piece of rebar or pipe, and the work is much easier after a good rain when the soil is moist. Place slow-release fertilizer in the holes according to product specifications then fill the balance of the hole with compost or enriched topsoil. Repeat the process at recommended intervals. Organic gardeners might like to try filling the holes with compost, composted manure, or manure "tea" as we did in India where slow-release fertilizer products were unavailable. The second technique involves the use of a root feeder, an implement readily available at most garden shops. This is basically a hollow tube with a head that contains a chamber for a pre-packaged nutrient and connects to a garden hose. The force of the water makes the hole and then dissolves the nutrients to fill the hole.

Plants grown in containers also flower best with a fertilizer high in phosphorus. Elizabeth Head related one experiment in fertilizing oleanders that deserves mention. She and Kewpie Gaido were preparing for a forthcoming Lawn & Garden Show in the month of February in Houston, Texas. They had many oleanders in containers but none that would be in bloom so early in the season. So they "pushed" the plants with heavy applications of fertilizer and were able to bring them into bloom for the show. Some seedlings that were only a few months old also flowered. Kewpie commented, "I have a bad habit of overfertilizing. I just throw the Osmokote on like it's free. But I don't think you can kill an oleander with too much fertilizer." (Note that she refers here only to a controlled-release fertilizer!)

The addition of bone meal as a slow-release nutrient to promote flowers and build hardier plants is also recommended, as is the application of chelated trace elements if the soil is lacking minerals. Magnesium sulfate (Epsom salt) helps to prevent leaf scorch and being the core of the chlorophyll molecule is a resonator ; of the photosynthetic process. In our first book The Handbook On Plumeria Culture, 'v6

Page 78

discussed experiments with potassium to strengthen cell walls in plumerias, thereby promoting greater cold tolerance. This would be an excellent research project for oleanders. Again, before adding any trace elements to your soil, we strongly recommend taking a soil test with one of the many kits available or having your local agricultural extension office send samples to a lab for testing.

Mulching

As a founder and vice-president of Living Earth Technology of Houston, Texas, I was involved in product formulation and had the opportunity to study the remarkable benefits of composting and mulching on a unprecedented scale. Living Earth Technology is today one of the largest manufacturers of compost, mulch, soils, soil amendments and growing media in the nation, processing hundreds of thousands of cubic yards annually. Using a natural, organic mulch such as compost, aged bark or leaf mold provides many benefits. Here are some of the major contributions mulch can make when applied around your oleanders and other plants.

1. Retains moisture: A 3 to 4 inch layer of mulch will help retain soil moisture, especially in the critical fibrous root zone in the top 6 inches or so, will prevent root scorch from excessive surface radiation, and reduce stress resulting from rapidly alternating cycles of watering and drying out.

2. Moderates soil temperature: Mulch is of significant value in cooling the surface layers of the soil in summer and keeping the root zone warmer in winter. To make your own test of the amount of temperature difference mulch can provide, on a hot summer day place your hand on an exposed area of soil and then place it under a 3 to 4 inch layer of mulch, also in an exposed location. We have often registered a difference of more than 40 degrees!

3. Suppresses weeds: A thick layer of mulch does an excellent job of suppressing weeds, especially a material with interlocking fibers such as that made from hardwood. Any mulch, however, is useful since it blocks the sunlight and inhibits weed seeds from germinating.

4. Adds valuable organic matter to soils: As mulch breaks down it adds valuable organics to the surface area of the soil, much as leaf litter does in a forest. Adding mulch each year improves the tilth of the soil and aids in building populations of beneficial soil organisms.

5. Improves appearance: A well-mulched bed or island of shrubs helps beautify any landscape. The neat, clean appearance will last for months with minimal maintenance.

6. Protects against soil erosion: On slopes and banks mulch is an invaluable asset in protecting against soil erosion. Aside from the obvious benefits of this in itself, it permits plants to establish more rapidly and provides root protection for years to come.

Page 79

Tree form oleander elegant and refined.

Oleander flowers and follicles (seed pods) photographed on Grand Cayman

Bouquet pruning allows light around the base and enables one to see into the landscape.

Umbrella form

Page 80

Pruning

In the following section we discuss general and specific types of pruning for oleanders. The most natural form of an oleander is globular, but large varieties allowed to grow as globular forms take up a vast amount of space and often obstruct the view. There are ordinances in cities throughout the country that limit the size of shrubs planted in medians and on corner lots in order to maintain visibility for motorists. Another negative in allowing some of the large oleanders to grow in their natural globular shape with dense foliage that extends to the ground is that they make excellent hiding places for thieves and muggers! Though dwarf forms are available and more are being developed through hybridization, we need not to be limited to these if our favorite flower happens to be on a larger variety since oleanders respond so well to various pruning treatments.

General Guidelines

Pruning requires considerable forethought to achieve the best aesthetic appearance for plants in your landscape. There are two basic types of pruning recommended for oleanders. The first is thinning by removing stems at ground level. Stems that are old, woody, or dead are always removed first in the thinning process. The second is "heading back" by cutting healthy stems to a point where you create a harmonious balance between size and shape. With annual pruning one can keep any oleander to approximately 60% of its ultimate height but we recommend never to remove more than % of its mass at a time. If you know the ultimate size of the plant you wish to have in a given space, choosing a cultivar with a similar natural habit will save much pruning labor in the future. We live by two pruning rules for most plants, but especially for oleanders. Never use hedge shears on oleanders! And remember that a well-pruned plant should appear as if it just grew that way naturally.

Clarence Pleasants remarked, "Of course, the real secret to the height of oleanders is pruning them now and then, not just a French haircut, but after they're a certain height, say six or eight feet (that's a general height), then it's wise to go snd take some of the older stems out and encourage some of the younger ones to grow. That's the easy way to keep the size down, if you trim two or three stems out every year."

In Galveston and areas with similar climates oleanders should not be pruned W the winter or spring. With the exception of the everblooming varieties, we suggest pruning no later than the first week in September and as early as mid-July when many plants finish blooming. The reason for this pruning schedule is that in warm climates oleanders tend to put on a spurt of growth, both leaves and flower buds, for two or three weeks in the early fall after the summer's heat and with the onset of. cooler days and nights. Also, with the coldest weather normally occurring in Decernber and January, new growth will have time to harden off before winter. Plants "st bloom only in spring may be pruned any time after flowering but early to midsummer is best to avoid removing the wood that will produce blooms the following sason. In colder areas plants should be pruned as early as possible in spring, especially

Page 81

dally to remove any winter damage the plant has incurred. The key point to remember is that oleanders carry latent flower buds on the mature wood. Pruning in late summer, or early fall at the very latest, allows new growth to regenerate and harden off. Pruning in winter or spring removes the mature, flowering wood and delays bloom until new growth matures.

There are many other reasons for pruning in addition to restricting size. Oleanders that bloom abundantly seem to reinvigorate themselves and come back more readily after heavy pruning. Any time an oleander is cut or frozen to the ground il will grow back from the base with a myriad of small stems creating the globular shape mentioned above. To reduce the size of a plant at the base, basal sucker? should be pulled off, not cut, to discourage regeneration. For oleanders that have compact forms, annual pruning is recommended to prevent legginess, especially i:

plants are not grown in full sun. When plants that have been grown outside most or the year are moved into a greenhouse for winter protection, they tend to stretch making pruning necessary. Ted Turner, Jr. has found it expedient to prune three times during the winter, allowing the plant to break each time between prunings to ensure a full plant the next year. One should always prune to remove weak, dead and crossing branches, diseased parts such as gall infestations, unhealthy and unsightly areas of freeze damage, or brown leavtes due to wind and salt burn. Since a tremendous amount of a plant's energy is expended in the production of seeds, pruning to remove seed pods will increase the number of blooms per plant and extend the flowering season.

Dwarf and Petite Oleanders

An expert in the culture of dwarfs and petites, Ted Turner, Sr. recommends pruning dwarf varieties fairly severely in the spring after all danger of frost is past. "Of course, any time you prune a plant you stimulate growth to a degree," he comments. "With oleanders you definitely do. It stimulates the growth and they're going to sprout and then, if there is a late freeze, you get hurt. But you still need to prune them as soon as possible so that you'll get blossoms at least by mid-spring."

For a long time Ted Jr. didn't recommend pruning the petites such as 'Carnival' and 'Petite Salmon', primarily because they never stop flowering. If there was no winter freeze the buds that were on the plant in late fall would open in early spring and the plants would bloom continuously through the summer. But he noticed that the old inflorescence stalks remained and looked like "fuzzy candles" sticking out four or five inches on the plant. Now he recommends giving them a "haircut" in the spring if there has not been a freeze.

Shrub Forms

To maintain oleanders in their natural globular form, prune back individual branches a few at a time to enhance the globular appearance. Never shear the leaves and growing tips to achieve a rounded form because you will not only have a plant with unsightly clipped foliage but you will have also cut away most of the flower buds.

Page 82

Multi-trunk Forms

Select any number (aesthetically it is best to choose an odd number) of the healthiest and most attractive stems to create a multi-trunk. Remove all the remaining stems and the lower side branches from the chosen stems so that the plants develop a full branching head at the height desired. Maintenance on this form is very high as new stems continually develop from the roots and new shoots emerge from the stems that were cut to the ground. If not regularly and assiduously pruned, an unsightly "window" effect is created. (See photo pg. 85) If, however, you begin with a young plant and pinch, rub out, or excise completely with a budding knife the latent or newly emerging leaf and stem buds, the task is made much easier.

Multi-trunk specimens are one of Ted Turner, Sr.'s specialties. "I love the multitrunk oleanders, I think they are gorgeous," he says. "It takes a lot of work to keep the sprouts off them, but after they get real, real old they don't sprout anymore." Another reason for creating multi-trunk forms in areas where there are high winds is that three or more trunks buffer each other and withstand the wind much better.

Bouquet Forms

This form provides an alternative to the natural, massive, globular shape of the larger oleander varieties. It allows light and air around the base of the plant as well as a much more open view, creating a vase-like appearance rather than a solid screen. Pruning a bouquet form begins with the standard pruning practice of removing dead or dying, weak and crossing branches, then reducing the overall size if desired. After this, remove at ground level as many of the outer stems as necessary to create a narrow base. It may be preferable to achieve this by also pruning away some of the older stems in the center of the plant leaving younger stems that will grow to take their place. If you simply cut back all the longest stems to the desired height, your plant will look like cluster of a woody canes with unsightly tufts at the top. To enhance the "bouquet" appearance, head back some of the remaining outer stems. This will further reduce the plant's diameter and initiate a flush of new leaves. (See photo, pg. 80)

Umbrella Forms

This technique involves binding several stems together at the desired height creating the appearance of a large single trunk, somewhat like the swollen caudexes of many tropical trees. Plants are allowed to branch just above the point where they are bound and arch outward to create this distinctive and eye-catching form. (See Photo, pg. 80)

Tree Forms, Patio Trees or Standards

The only tree forms available to the public for many years were the "patio trees" from Monrovia Nursery in Azusa, California. These were pruned with six feet

Page 83

of trunk. Ted Turner, Jr. remarked that plants pruned to this height would have to be permanently staked in Corpus Christi. All tree form oleanders must be staked unless they are in a totally protected area away from gusts and high winds that can easily snap off the head. Stake the trunks with a steel reinforcing rod or galvanized pipe driven down parallel to the trunk of the tree and fairly close to it. Secure the tree at the height of the first branches to keep the head from twisting. Keeping the heads pruned a bit close to prevent them from becoming too massive will lower wind resistance. In windy areas patio trees should have trunks no higher than 3 to 4 feet and should be planted in a protected spot. Oleanders trained in this manner take up much less space than globular or bouquet forms and are appropriate for gardens with limited space. Since they cast very little shade one can grow a large selection of low-growing groundcovers or colorful annuals beneath them. Oleander trees in bloom are a magnificent sight but one must follow the laws of Nature to create this unique form.

It is not possible to create a tree form by cutting away all the stems of a shrub except one. With an established oleander this would create a pruning nightmare worthy of a Chaplin film with new shoots growing back faster than one could remove them. The ideal way is to begin with a large, straight, rooted cutting or a young whip on which you can rub out any emerging new growth. This will channel the energy up the trunk and you can allow the plant to branch at whatever height you prefer. There are two techniques for achieving tree forms that we recommend for simplicity and dependability. The first method, utilized by Gary Outenreath at Moody Gardens, is to crowd together a number of oleander seedlings or cuttings. The plants will grow straight upwards, stretching to attain the sunlight, and being crowded together few side shoots will develop. Those that do can easily be rubbed out. Plants grown in this manner do not tend to sucker at the base. When they achieve the height you want, pinch out the tip and they will branch. This same method is used for hibiscus. The second technique is to layer (see sections on air layering and ground layering) a stem of the height and diameter you want. Since oleanders grow rapidly, especially in warm climates, you can literally watch your tree develop in one or two seasons. Remember, too, that you have a wide palette to choose from, not only in color selection but in the different sized cultivars that are available.

An innovative technique Bob Newding uses for growing a tree form is to slit a piece of PVC pipe along its length and fit a sleeve around the base of the stem. This accomplishes two useful things; it prevents damage to the tree from string trimmers and will shade the trunk, inhibiting shoots from emerging from the base and sides, (photo, pg. 74)

Excellent examples of tree form oleanders may be seen at the entrance to Moody Gardens in Galveston, Texas, and in many other landscaped parks, avenues and residences throughout the city. They are also used with stunning effect at Disneyland and Disneyworld. Tree forms provide color over a long growing season and are especially beautiful in flower beds and lawns. Since oleanders are evergreen they are not messy due to excessive leaf drop. The tree form, being less massive, is also a good choice in an area where one might wish to avoid obstructing a view. We have seen many elegant specimens planted in large con

Page 84

Young standards (tree forms) being trained at Turner's Gardenland, Corpus Christi

Multi-stems at Galveston College.

Multi-stems in need of pruning to remove basal growth.

Page 85

tamers in front of office buildings and in landscaped settings around malls in southern California.

Hedges and Screens

It has been Bob Newding's experience that if you plant varieties with different mature heights when creating a hedge or screen, the larger plants will take over unless all are pruned in accordance with each variety's ultimate height. By pruning and shaping each plant as an individual, you will create an interesting grouping with varying heights and colors. Planting only one variety simplifies pruning but creates the completely different look of a uniform hedge. When closely planted, oleander hedges eventually become virtually impenetrable, an effective screen against foot traffic, animals, and even dust and noise.

Root Pruning

Root pruning is another method of keeping plants to size. However, this is much easier said than done unless plants are fairly young. Using a spade, cut down vertically around the drip line of the plant to the depth of the spade. This will limit horizontal root growth and thereby keep plant size restrained.

Hybridizing

As a result of discussions with a friend at Longwood Gardens in Pennsylvania, Clarence Pleasants was encouraged to begin hybridizing with an aim toward first developing greater hardiness, extending the growing range of oleanders into cooler zones, and then to seek good flowering qualities. In hybridizing, one must begin with a clear goal and select existing plants that have the inherent genetic qualities to lead to the realization of that goal. As an example, Ted Turner, Sr. wanted to develop a free-blooming plant with red flowers that was more dwarfed and compact than any existing cultivars. Thus far he has succeeded in two of his three goals and is still working towards achieving the elusive red color. Monrovia Nursery has concentrated on free-blooming plants that are compact in size and have unique, almost fluorescent colors.

Most of the cultivars we have listed are the result of pollination by insects, namely butterflies and moths, as self-pollination of oleanders rarely occurs in Nature. In more than a hundred hand-pollinations, Frank Pagen found that all crosspollinations between cultivars appeared to be compatible. "In every combination of cultivars tested, the pollen tubes reached the ovules without difficulty," he reported. This section is based, in large part, on the studies of Pagen and the following is quoted with his kind permission. It is included to inspire those who would like to develop new hybrids by describing the procedure for successful pollination. (Please refer to the excellent line drawings by Pagen, pg. 87, 88)

Page 86

The flower of Nerium oleander L.1. corolla from above x 3/4; 2. lateral view x 3/4; 3. lengthwise section of the lower tube, 2 anthers removed x 6; 4. cone of anthers x 7; 5. position of anther and pistil head x 7; 6. anther, •"laxial view x 7; 7. id., abnxial view x 7 (drawn from living plants).

Lustration courtesy F.J.J. Pagen

Page 87

H. van Rheede tot Drakestein. 1689. Hortus Malabaricus, Vol. 9.1.1: "Tsjovanna-areli". Copper engraving.

Illustration courtesy F.J.J. Pagen

Page 88

The flower of Nerium oleander features a pistil with a morphologically highly differentiated pistil head.... The entire pistil head is covered with bristly hairs, which determine, by their length, the specific shape of the pistil head. The central cylindrical part of the pistil head is covered with rather short hairs, inserted on a glandular epithelium which produces an adhesive. At the upper edge of the cylindrical part the hairs are longer, pointing outward and upward, thus forming a ring or wreath. On the lower part of the pistil head long hairs, pointing downward, are arranged in a sinuous line around the cylinder, forming a collar. Below this collar, which hangs down from the pistil head, is a circular depression marking the transition to the style. The pistil head is topped by two short erect appendages.

This morphological differentiation is accompanied by an analogous functional differentiation. Only specific areas on the pistil head have a stigmatic function and are receptive for pollen tubes.

The receptive stigmatic area evidently is located on the circular depression, right below the collar on the lower part of the pistil head.... Pollen grains will germinate on other parts of the moist surface of the pistil head as well, but the pollen tubes will grow along this surface without penetrating it. Penetration is exclusively possible in the indicated area.

The Nerium oleander flower has an intricate construction connected with a refined pollination mechanism.

Dark, usually carmine red, longitudinal lines in the corolla throat point to the nectaries around the ovary at the base of the funnel-shaped corolla tube. However, much of the passage is blocked by the corona lobes and by the woolly plug formed by the intertwisted appendages of the anthers. The short-stalked stamens are inserted at the middle of the corolla tube. The anthers have firm sagittate plates outside and are introrse, adhering to the pistil head, thus forming a cone in the center of the flower. The pollen is shed inside the cone of anthers and collects on the top of the pistil head, completely isolated from the stigmatic area below the collar at the lower part of the pistil head.

Between the five triangular anthers are chinks, narrowing to the top of the cone. The insect's tongue can be inserted in the tube through these chinks or through the openings between the filaments. In either case, when the tongue is withdrawn it gets jammed between the adjacent anthers. A powerful pull is necessary to release the tongue and in this action the tongue moves along the cylindrical part of the pistil head, where it gets covered with adhesive, and then through the pollen chamber, where pollen grains are glued to the tongue. The insect is probably disturbed and leaves the flower. In another oleander flower the procedure is repeated and when the tongue is withdrawn it brushes past the collar hanging down from the pistil head. Thus, the pollen is deposited

Page 89

below the collar, exactly on the receptive stigmatic area. Moving upward the tongue passes again along the cylindrical part of the pistil head and through the pollen chamber. The tongue is covered again with polJen and the insect is ready lo pollinate another oleander flower.

The Nerium oleander flower is adapted to pollination by Lepidoptera (butterflies and moths). Only these insects have a tongue long enough to reach the bottom of the corolla tube and have the strength and endurance need to release their tongue from the trap and establish pollination of the oleander flower.

Pagen utilized fluorescent microscopy to locate the stigmatic area on the pistil of oleanders. Through the experiments he conducted, the exact location of the recep tive area was pinpointed as was the compatibility of self-pollinations and crosspollinations between cultivars. Fourteen single-flowered plants provided by thi' Dutch Oleander Society were the basis for the experiment.

Ted Turner, Sr. often jokes with people that he uses "Q-tips" to pollinate olean ders, but he becomes excited and almost poetic when he describes a cross section o; a flower under a microscope. "\ think that is the most fascinating thing in the world — it looks like a pot of gold on top of the stamens!"

Now that we have a clear understanding of how to pollinate an oleander, wr; can proceed by selecting two newly opened flowers. We have not studied the period of receptivity of oleanders, but have found with plumerias, hibiscus and many othe • tropical plants that the highest receptivity is around 10:00 a.m., so this would probably be a good time to begin. Be sure to emasculate the flowers at the beginning ti' prevent any possibility of self-pollination and cover them when finished with fine gauze or cheesecloth to prevent any other pollen from entering. Tag the pollinated flowers, indicating first the seed parent followed by the pollen parent and the date. Example: 'Petite Pink' (seed) x 'Sorrento' (pollen).

A Perfect Lady

I knew a girl who was so pure

She couldn't say the word manure.

Indeed, her modesty was such

She wouldn't pass a Rabbit- hutch;

And butterflies upon the wing

Would make her blush like anything.

That lady is a gardener now,

And all her views have changed, somehow.

She squashes greenfly with her thumb,

And knows how little snow drops come:

In fact, the garden she has got,

Has broadened out her mind a lot.

Reginald Arkell

Page 90

Dwarfing Plants with Growth Retardants

Oleanders may be dwarfed by using the commercially available growth retardant, Cyclocel. From rooted tip cuttings to finished plants takes about one year and requires at least three applications. Considerable experience is necessary to learn when to apply as well as the proper concentration. If the retardant is not continually applied at regular intervals plants will resume their normal growth rates, so for most oleander enthusiasts, choosing a dwarf or compact variety is a more practical alternative.

Pests, Diseases, Problems and Solutions

There is virtually no insect or disease that can kill an oleander with the exception of root rot diseases caused by poor drainage and a rare canker that attacks severely stressed plants. In fact, chemicals used to treat insect attacks may occasionally cause more damage than the insect itself. The Turners caution against using Diazinon on oleanders as this chemical, in their experience, will kill them, even if spray drifts over when spraying other plants. Although oleanders are noted for their resistance to pests and diseases, they do suffer occasional attacks. We encountered a twig girdler in India that would cut around oleander stems and decimate plants quite rapidly but new growth would simply sprout below the girdled area. In general, insects favor other plants and will attack them first. The Turners note that if you have mites on an oleander, all you have to do is move a Datura (Angels Trumpet) or Chamadorea (Parlor Palm) next to it and they'll leave the oleander in a hurry. Ted says that you can almost see them jumping down! Most pests are fairly easy to control and although some problems are more serious than others it should be remembered that, by and large, regardless of the rather extensive list that follows, there are few plants that give so much beauty with so little care.

Aphids: Aphids are probably the most common insect pest of oleanders. These sucking insects feed on the sap of leaves and flower buds and cause them to be deformed. There is even an aphid named for oleanders, the yellow-bodied oleander aphid Aphis nerii. In a most interesting article in Nerium News, (Spring-summer"93), Ken Steblein writes of the Integrated Pest Management (IPM) program at Disneyworld. In addition to beautifying the landscape, oleanders are used as a host plant for the oleander aphid which feeds exclusively on oleander leaves. The IPM department introduces to the oleander plants the tiny parasitic wasp Aphidus matricatriae which lays eggs on the aphid for approximately two weeks and causes the aphid's body to be covered with a hard shell like a "mummy." At temperatures around seventy degrees, the eggs hatch inside the aphid shell and feed for about two more Weeks. Oleander leaves with aphid "mummies" are then placed among the vegetable crops in the Epcot Center's Economic Greenhouse. The wasps mature, eat a hole w the aphid "mummy" and seek out aphids on the vegetables where they repeat the cycle. Oleanders are used again as hosts when necessary to maintain a constant supply of the parasitic wasps.

Page 91

On a smaller scale, aphids are fairly easy to control in the early stages of infestation by simply washing them off with a strong stream of water. If you use a sprayer, add a teaspoon of liquid dishwashing detergent per gallon of water and spray with maximum pressure. If you experience a heavier infestation, you can get things under control with one of the following formulas:

1. Two tablespoons each plain vinegar and household ammonia per gallon of water. For more effective application use a surfactant such as liquid dishwashing detergent or a commercially available spreader-sticker which, in addition to breaking the surface tension of the water (as detergent does) to provide better coverage, will also adhere the material to the leaf and stem surfaces.

2. If you have a serious infestation, Malathion (applied exactly according to directions) has proven effective, especially in combination with a surfactant.

3. The Turners use Phycam, a wettable powder, to control aphids, spraying very early in the morning when it's cool. They have found that powderec insecticides tend to be less injurious ta plants than oil based sprays anc caution that the use of Sevin on petite oleanders can cause the growing tip1 to burn.

Ants are known to transport, or "farm out," insects such as aphids to differen: areas of a plant and, in return, feed on their honeydew secretions. It is therefore important to look for ants when you see the first sign of aphids and to treat them as well.

Canker: In the spring of 1989 there were isolated reports from the Texas gulf coast, including the Galveston Country Club, of a mysterious disease affecting established oleanders. According to an article in Nerium Nezus (Summer '89), in th'; instances observed, leaves turned gray and then yellow before falling to the ground and eventually the entire plant died rather suddenly. The problem was identified b T the Plant Diagnostic Laboratory at Texas A&M University as Botryodiplodia, a weal, opportunistic fungus or canker that damages the vascular system of the plant. Thi fungus is ubiquitous, but in order to enter a plant it must be accompanied by stress factors such as freeze, drought, high wind, nutrient deficiency, chemical damagt, etc. Though described as a weak fungus, it does not readily respond to available fungicides. Some control was achieved by spraying with a fungicide containing Benomyi every two weeks and also with Kocide 101, but it was equally important to meticulously remove any and all symptomatic branches. It was observed that tb5 worst infections occurred on pink and red varieties. Always handle and destroy infected prunings with care to avoid contaminating other plants, but do not burq because of the toxic fumes from the oleander wood. Disinfect pruning tools with a 10% solution of chlorine bleach.

Caterpillars: To date, four species of caterpillars have been observed feedir.c, on oleanders. One, the Oleander Caterpillar Syntomeida epilais jucundissima, is a stinging type that should be avoided. It is a serious problem in Florida and can rapid iy

Page 92

defoliate plants if not treated, but can usually be checked with one application of Sevin or Malathion. We have no reports of it being a problem in Galveston or other areas of the United States. Our recommendation is to spray with Bacillus thuringiensis which is harmless to humans but highly effective against all kinds of caterpillars.

Dodder: Dodder is a climbing parasitic plant that has been observed on oleanders growing on the causeway entering Galveston. In appearance it resembles a tangled clump of yellow-orange strings. The parasite reproduces itself by seed and although it does not seem to spread rapidly enough to become a serious threat, it should be removed and destroyed.

Fungal Diseases: Powdery mildew, leaf spot (black spot), and root rot can all be prevented or severely curtailed by keeping containerized plants on the dry side during the winter and by providing adequate drainage to plants grown in the ground. Kocide 101 is a good all-purpose, copper-based fungicide that is effective and fairly safe to use.

In a nursery situation where many pots are close together in an area, the Turners have often had problems with two types of fungus that attack the petite oleanders, especially those shipped in from the west coast. One appears similar to dampening off fungus and the other attacks the stems, quickly spreading from one plant to another. They have observed this on 10% to 15% of the gallon size material coming from California, but when the plants are planted out in the landscape the

Petite Pink

Page 93

problem does not occur, seeming to be specific to nursery conditions. They have found Ornalin to be an effective control but advise never to use Benomyi on oleanders for control of fungus. Once, when Ted Sr. was spraying Benomyi on other plants in his greenhouse, he accidentally sprayed some oleanders and lost 14,000 cuttings at one time!

Mealybugs: These are small, soft-bodied, sucking insects covered with a white, cotton-like substance. Two species have been reported on oleanders. For effective control use the same formulas as mentioned above for aphids.

Nematodes: Clarence Pleasants noted that nematodes were found in Galveston but this is the only report to date and the incidence appears to be very localized.

Oleander gall: The bane of oleanders is a wart-like, bacterial gall (Pseudomonas syringae) that appears on succulent, non-woody parts of the plant such as leaves and younger stems. Although not lethal, it is very unsightly causing streaks of swollen tissue or numerous knots along the infected area and can even cause new leaves to deform. 1: is easily spread, especially by infected pruning tools, and there is no chemical cure for it, In an article appearing in the Galveston Daily News, November 20,1991, Dr. William M. Johnson, a plant pathologist with the Galveston County Extension Office, concurred thai: the gall is caused by a bacterium and explained that it first multiplies within the gall tissue, then migrates to the surface where it is easily spread to other plants or parts of th-3 same plant. Gary Outenreath informs us that it is both airborne and carried by insect; and that it enters through the flowers, distorting and often blackening them. The Turn ers find that in Corpus Christi it is more prevalent during a cool spring with very cloud / days and temperatures around 40 degrees, and is occasionally seen under foggy conditions on' plants near water. If a plant is infested with gall, the infected parts must b3 carefully removed and completely destroyed so as not to spread the bacteria. Pruning tools should be dipped in a 10% solution of chlorine bleach each time a cut is made. Thi 3 may be laborious but extreme care must be taken with a bacteria that is so highly contagious. If a plant is heavily infested it may be necessary to cut it as close to the ground as possible and remove all the leaf litter as bacterial spores are also in the litter. Spray the exposed stump with a 10% solution of chlorine bleach. In one growing season the plant can put on four to five feet of beautiful new globular growth and in two years will reach its full height once again. The best time to look for gall is mid-summer after many plants have finished their major flush of bloom and after especially rainy or humid weather.

Root Rot: This is a common cultural problem usually caused by overwatering plants in containers or providing insufficient drainage for plants in the landscape.

Scale insects: According to the International Oleander Society, seven different species of scale insects have been identified on oleanders. They are soft-bodied, sucking insects that subsist on the juices in plants and secrete a waxy substance over themselves that affords them protection. Scale insects are often very difficult to control and can do serious damage if not treated. In order to effectively destroy scale populations, their protective coating must be penetrated. The spray formulations mentioned above for aphids should do the job but be especially careful to thoroughly.

Page 94

spray the backs of leaves since this is where scale is normally attached. Scale insects can weaken a plant severely so that it will be susceptible to a host of other insects and/or diseases. The Turners have used oil sprays successfully but they offer some cautionary advice. Ted Sr. says, "Leave it on about an hour, then wash it off if you don't want to hurt anything. That's long enough to kill any kind of insect that's on there. I never was one for leaving insecticide on plants all day long. I hate to spray for anything but I have to now and then."

Snails: Snails and slugs are usually only a problem in spring as they will feed on flowers but can be controlled naturally by sinking saucers of beer in the ground, or chemically with a variety of commercially available baits placed around the plant.

Spider Mites: Spider mites are rarely encountered on plants growing outdoors but can be a problem in enclosed areas such as greenhouses or wherever ventilation is inadequate. Populations can increase rapidly, especially during hot weather, and the mites are so tiny they often go unobserved until a serious infestation is underway. Kelthane is effective in the control of spider mites in greenhouse conditions but it is best to follow the Turners' advice and apply all chemicals when temperatures are cool and then wash them off after an hour or two.

Witches broom: Witches broom is an abnormal growth of a number of shoots that may grow in a similar direction or may become a tangled mass, hence the name. It has numerous possible causes, the primary ones being infection by various fungi such as rust, mite infestations in the growing tip of the plant, parasites and, on occasion, low temperatures. The form of witches broom that attacks oleanders is unsightly but not fatal, and can be controlled by simply cutting out and destroying the affected parts.

Yellowing of leaves: Chlorosis, which is a sign of iron deficiency indicated by yellow leaves with green veins, and yellowing leaves due to lack of nitrogen are not usually a problem with oleanders. If you should observe chlorosis, apply a chelated trace element mix either in granular or, for faster results, water-soluble form. Nitrogen deficiency is easily remedied by an application of fertilizer as mentioned previously. Occasionally the lower leaves on plants will turn yellow during periods of drought or intense heat. This is a natural phenomena, the plant's way of dealing with stress. With the onset of cooler weather and/or sufficient moisture, the yellow leaves will fall to the ground or can be washed off with a hose as they are replaced by new growth.

Cold Tolerance, Hardiness

Of all the oleanders, those with red flowers appear to be the most cold tolerant. One indication of hardiness is the thickness of the leaves. The thin, light green leaves often found in the free-blooming varieties are generally indicative of more .tender varieties and dark green, leathery leaves characterize hardier forms. The tender varieties are also more susceptible to wind burn. Clarence Pleasants offers

Page 95

some fascinating insights on the ability of oleanders to become progressively hardier. "They have a tendency to adapt," he says. "Our [garden] supervisor, the man who encouraged me, would have us root these plants in spring and we'd grow them on. We didn't keep them inside long. After they were out of the 4 inch po; area and of a size ready to transplant, we'd plan: them in a row in a raiseil bed for drainage out in the field, out where it'; cold, cold, cold, in full sun and with frost to keep them from being too aggressive in growth. This was the experimental stage where he [his supervisor] felt you could find the hardiest

John Samuels

and the best. Most of the plants would live and they'd grow very slow." Pleasant? goes on to say that his supervisor considered the first couple of years to be the most important. All of the plants would die to the ground in the first winter and man;/ would come back the following spring. In the second year many plants would not die completely to the ground and would have hardy growth alive throughout the winter. It the third year the remaining plants would be dug up and planted in a sunny area with poor soil, little fertilizer and little water. This treatment toughened the plants and led to many more hardy varieties. Some other salient observations Pleasants makes is that double-flowered varieties do not appear to be as hardy as single-flowered forms, and fragrant flowers seem to come from more tender parents or from a milder area of the world. This concurs with our experiences with oleanders in India and southeast Asia.

Certain oleander cultivars are able to withstand temperatures well below freezing. The RHS Dictionary of Gardening mentions oleanders tolerating 14° F for short periods. As suggested above, hardiness among cultivars is highly variable. Some tender varieties are suitable only for growing in containers or the warmest zones while others show no sign of damage during lengthy periods of cold such as the December 1983 freeze in Texas.

Cold tolerance can be increased by withholding water and fertilizer in lale summer and early fall, allowing new growth to harden off before the onset of colJ

Page 96

weather. It has been observed in Galveston that when many varieties are subjected to cold they are stimulated the next spring to grow and flower even more abundantly than before.

Drought Tolerance

As with plumerias and many other members of the Apocynaceae family, oleanders are remarkably drought tolerant. The Turners relate an experience they once \ad trying to destroy a surfeit of undesirable plants: "You can't kill them with Round -i like you think you can. We'd dump them out on a road to let them expire and we d come back and they were still alive. They're extremely drought tolerant. You can't kill them once they get started!" The Turners also note that even if the leaves of plants are burned from drought, it is still possible to take cuttings from them.

Salt Tolerance

Although we have read some accounts from the Caribbean Islands stating that oleanders cannot grow in saline areas, this is contrary to the Turners' experience in Corpus Christi and to Newding's in Galveston. The Turners have found that not only are the leaves salt tolerant, the roots are as well. In many areas of Corpus Christi one can literally see the salt buildup as a crust on top of the soil. Ted Sr. notes that oleanders are one of the few plants that can survive under these conditions. (See also Chapter 9, "Oleanders in the Landscape".)

Overwintering and Freezes

Oleanders tend to become dormant with the onset of the first cold weather and should not be watered or fertilized until new growth begins in spring. The Turners have saved thousands of hibiscus, bougainvilleas and oleanders that have frozen to the ground with a technique they discovered. After the freeze, rake the soil back exposing some underground stems, then wash the soil away. New growth will be stimulated to emerge from the tops of the anchor roots below the damaged area. The tender new growth that regenerates will be very susceptible to any subsequent freezes and should be mulched heavily, at least ten to twelve inches, if freezing temperatures recur. Be sure to remove the mulch as soon as temperatures permit, however, to again expose the roots to the sun.

Rose collars about 6 inches in length can be placed around oleander stems at ground level and filled with mulch or soil to keep the base of the plant from freezing. Protecting this much of the stems of small varieties enables them to produce new growth and even bloom again within a few months. Larger varieties may take longer but will still recover much sooner than if frozen to the ground. Another alternative for a plant that is too large to cover is to cut it down to a size you can cover! — in a hard freeze the top growth would probably be lost anyway. A common winter treatment for roses is also effective; simply cover as much of the base of the plant as Possible with soil and remove when freezing weather is past.

Page 97

In summary, oleanders can endure several degrees of frost and even repeated freezes as long as they are brief. Problems occur when low temperatures last more than two or three days.

Growing Oleanders in Containers

Americans have been growing oleanders in containers since they were brought across the sea by early settlers from the Mediterranean, but their history as cherished container plants in Europe and the British Isles stretches back much farther than that. Placed in formal planters on steps and terraces in full sun out of doors in summer, and mixed with flowering tropicals and subtropicals such as hibiscus and bougainvilleas in a glass house or conservatory during winter, oleanders have long been considered one of the finest plants for container culture.

We have mentioned that tree forms are excellent for pots and planters as are the more compact varieties, but any oleander

Turner's Kirn Bell™

can be grown in a container with occasional pruning and shaping. As corresponding secretary for the International Oleander Society, Elizabeth Head has received letters from people throughout the United States telling of their successes with pot culture. One Is from a gardener in Michigan who has oleanders in full bloom all summer in tubs along his driveway. The petites and dwarf forms are especially suited for container culture not only because they require less pruning, but because they will often flower prolifically even in small pots. In a warm climate one can transplant an oleander liner (9/2 inch pot) into a one gallon container on March 1st and it will be blooming in April. Also, because they don't require large containers, they are easily moved around. Ted Turner enthusiastically comments, "You should see the 'Petite Salmon', the original that came from the [Los Angeles State and County] Arboretum! If you'll put three gallon

PaGge- 98

can plants in a 14 inch container, you've got an oleander that is over 3 feet across and 5/2 feet tall and you just can't beat that out on the decks, out over the salt water where the decks go out over the canals. You can't beat them out there — they'll take the wind, they'll take the sun, and they'll take the salt breeze much better than almost anything else."

A plumeria enthusiast for many years, our friend Jim Nicholas subsequently became interested in oleanders and has shared some fascinating experiences growing them in 6 to 8 inch containers in Connecticut. Jim usually uses sand as a rooting medium but told us about once receiving a package of cuttings only to find he had no sand, so he put them in water. After just four days he discovered that 'Ed Barr' was already putting out roots! He has found that the easiest and quickest varieties to root, even during the winter, are 'Little Red', 'Ed Barr' and 'Magnolia Willis Sealy'. After rooting, Jim moves the plants into small containers using a very light potting soil or a soilless mix to which he adds sand for added drainage and stability. He has successfully flowered all the varieties he has tried; some, such as 'Magnolia Willis Sealy', even bloom profusely in the winter under Gro-lights. But the secret to flowering plants in small pots, he says, is in the fertilizer. By applying a formula low in nitrogen to restrict stem growth and high in phosphorus to encourage bloom, Jim has plants no larger than 5/2 feet tall flowering prolifically nearly year-round. Smaller plants are overwintered under Gro-lights where they continue to grow and often bloom, others are kept in a west window where they rest without shedding leaves until spring. The only insect problems Jim has experienced have been one incidence of scale on a plant already weakened with a physical injury to the bark, and a few aphids which he says are a feast for the ladybugs that appear instantly when he puts the plants outdoors in the spring.

Choosing a Container

As mentioned earlier, oleanders develop many fibrous roots that spread laterally but, in general, do not tend to grow very deep. For this reason it is best to plant them in containers that are wider than they are tall. Azalea pots are excellent choices as are tubs and whiskey barrels.

Soil Mixes for Containers

Although it may be necessary to water more frequently in the hottest weather, We recommend a highly porous, well-drained mix for oleanders grown in containers. A successful mix should contain ample amounts of compost or well-decomposed organic Matter, sharp sand, a time-release fertilizer and fine aged bark. A small amount of sterilized soil can be added to a mix but it is best not to include local topsoil as it may contain bacteria, fungi or nematodes. More plants are killed by overwatering (too much TLC) than any other cause so bark nuggets or clay crockery pieces should be placed at the bottom of the container for added drainage. Always mulch the top of the container with a 2 to 3 inch layer of compost or well-decomposed organic matter to help retain moisture and to protect feeder roots from excessive heat.

Page 99

Repotting Container Grown Oleanders

Horticultural rules often change over the decades, sometimes reverting to practices of. an earlier time, sometimes advancing with newly acquired knowledge. Occasionally, two schools of thought exist concurrently. One concept in vogue today is to disturb root systems as little as possible and not to slice or comb encircling roots to avoid causing additional stress. Our practice has always been to seek to understand the nature of the plant and then, using care, take whatever steps are necessary to enhance its health, growth, flowering, fruiting, etc. We find that with oleanders, as with many other plants, the best practice is to comb down carefully without tearing and loosen all encircling roots, cutting off ones that cannot be redirected. After experimenting with many implements — knives, forks, three-pronged cultivators, weeding forks and more — we find that a short screwdriver (about 6" long) is the most effective and does the least damage. After loosening encircling roots, follow the same procedure as for transplanting. Be sure to have everything in readiness before you begin work. (See also the section on "Planting in the Ground".)

Oleanders don't mind being rootbound for a season or two, so transplanting is only needed when they outgrow their container creating an aesthetic imbalance, or ^when plant performance, even with supplemental fertilizing, indicates the need for a larger container.

Topdressing

If roots are pushing through the bottom of the container, repotting to the next larger size is advisable. If this is impractical, then topdressing by removing two or three inches of the old soil, including some roots, and adding compost or well-rotted manure will reinvigorate plants and suffice for another season. Topdressing should be done before the flower buds have formed. A second technique is to remove the root ball and cut back encircling roots or roots pushing through the drain holes in the container. Carefully remove a little soil from the base, top and sides of the rootball and replant with new soil.

Watering in Containers

During warm weather when plants are actively growing, water as often as necessary to supply roots with sufficient moisture and always water thoroughly. Allow the soil to become almost dry between waterings. Oleanders do not like "wet feet" so keep them on the dry side during cool and wet weather. Reduce watering significantly in early to mid-autumn, allowing new growth to harden off before winter.

Fertilizing in Containers

European growers recommend using a water-soluble fertilizer every two weeks once growth has begun in the spring and continuing this program through the end of summer. With the advances in timed-release or sustained-release fertilizers in the

Page 100

1980's and 90's, we recommend alternating these with water-soluble formulas, especially those high in phosphorus since they are immediately available to the plant's system and insure a constant nutrient supply. For those wishing to avoid the use of chemicals, container culture is an ideal opportunity to try an organic fertilizing method we used successfully in India, "manure tea." The tea is made by soaking one part manure in three parts water for several days to a week. After soaking strain off the liquid, dilute by half if plants are very young and apply to the surface of the container. Each time you water, small amounts of nutrients will be dissolved and carried to the roots. Manure teas may also be made from other organic ingredients such as cottonseed meal and alfalfa pellets.

Pruning in Containers

There is a fair amount of contradictory advice on the subject of pruning plants in containers. For the most part, a common sense approach is all that's needed in addition to an understanding of the plant's nature. Pruning in late summer or early autumn will allow new growth to harden off before the onset of cold weather. Pruning in early spring to remove weak stems and old wood, and to achieve a desired height is also advisable. Periodic thinning will assure compactness and greater density. A helpful tip to remember is to remove any side shoots that develop just below the flower clusters in order to prevent flower buds from falling off. This is especially important for plants grown indoors.

Overwintering in Containers

Overwintering container grown plants is not difficult. A cool place such as a cellar, where temperatures may vary from the mid 30's to the low 50's F., is ideal. Although there is some disagreement on the amount of water to provide during winter dormancy, most growers advise that it should be little to none. As our experience with plumerias has shown, keeping plants on the dry side is the best course to follow. Plants stored in cellars during the winter should have some amount of light as well as adequate ventilation. Never fertilize during dormancy.

Sometimes an illuminating experience contradicts conventional wisdom and practice. One such case occurred during the hard freeze that hit southern Texas in December, 1983. We were living in Houston at the time and watched in disbelief as temperatures dropped into the single digits. In fact, in the Zone 9 area, the temperature did not get above freezing for five days and thousands of plants were killed. Farther south in Corpus Christ! the Turners experienced similar temperatures, recording seven degrees at one point in front of their nursery. Ted Jr. commented, 'Now, as far as I know, every oleander in this town was killed to the ground. However, I had a 'Petite Pink' in a container on the dock at my house and I can't remember the last time I watered it. I mean, it was so dry that it was crinkled! When I saw it still crinkled, I thought it was from the freeze, but when I watered it, it leafed right out to the ends of the branches." Ted Sr. remembers a few other petite oleanders that survived the freeze. One was 'Carnival' which he had planted in a container on the north side of a customer's residence. These were fairly young plants with a total

Page 101

height, including the pot, of not more than feet. The family went away on vacation for three or four weeks, returning after the freeze. During this time the plants received no water and were bone dry. A month or so later Ted visited the house and remarked that the oleanders in the pots had really grown back fast. The owner told him that they had never frozen! The Turners say that now they only water oleanders in the nursery when they expect a light freeze and heavy winds in order to prevent desiccation of the leaf surface; in a hard freeze they don't water at all. It should be remembered that this practice is only for oleanders in containers. Plants in the ground must be kept well-watered and heavily mulched before a freeze.

With the first sign of growth in spring, situate plants so they can receive the maximum amount of sunlight. A good general rule of thumb is to move oleanders outdoors when it is safe to plant tomatoes in the garden.

Tips for Year-round Container Culture Indoors

Plants grown permanently in greenhouses and garden rooms will necessarily have somewhat different requirements than those grown out-of-doors most of the year but, in general, the basic principles regarding culture remain the same and many gardeners have great success growing oleanders indoors.

Experienced growers agree that most oleanders will bloom in a 6 to 8 inch pot with good care, but a 12 inch container is ideal if you want plants to attain greater mass. Dwarf forms are especially desirable for growing indoors year-round for the reasons described above. Soil requirements are essentially the same for all container grown oleanders in that the medium needs to be fertile, porous and very welldrained to be successful. Fertilizing should also follow the guidelines discussed above, bearing in

Turner's Daisy'

Page 102

mind that growth rates may be somewhat slower during spring and summer and winter dormancy less pronounced.

Providing adequate light for plants such as oleanders that normally require a lot of sun is a challenge for many indoor gardeners. In our research we have found several references indicating that oleanders do very well under artificial lights. There are numerous books available on the subject of light gardening and equipment catalogs offer an assortment of fixtures, bulbs, light units, etc. We have not grown oleanders under artificial light, but for other plants we have found ordinary florescent fixtures with Gro-bulbs and a timer to be the simplest and most flexible arrangement.

Plant Selection Criteria

When purchasing oleanders at local nurseries take time to examine them carefully. Do not choose potbound plants where roots may be pushing through the drain holes or even at times visibly encircling themselves at the top of the container. Look for insects on stems and above and below leaves. Do not purchase plants with damaged or broken branches, die-back, symptoms of chlorosis or evidence of bacterial gall. Always select bushy, healthy plants with lush growth and refrain from "bargain" plants that may be weak, spindly or off-color. It will usually cost more in the long run to nurse such plants back to health. Choose the best plant for the intended planting site and avoid unreliable names such as Common Red, Hardy Pink, Double Yellow, etc. •

Die when I may, I want it said of me

by those who now me best,

that I always plucked a thistle and planted a flower

where I thought a flower would grow.

Abraham Lincoln

Page 103