Oleanders as Indoor/Outdoor Plants by Paula Szilard If you haven’t given serious consideration to growing oleanders indoors you are not alone. For one thing, they can get quite tall. The tallest varieties range in size from 12-20 feet in height, effectively limiting them to the great outdoors. The intermediate size varieties will grow anywhere from 8-12 feet tall. Growing these in pots and pruning them regularly should keep them at around 6 feet or less. In addition to frequent pruning, some people try to keep them short by feeding them chiefly with high phosphorus fertilizers intended for blooming plants. This is said to keep the vegetative growth in check, according to an article on the website of the International Oleander Society (www.oleander.org). Grower Steve Golden of Cypress Gardens Nursery in Pasadena, Texas does not recommend this practice. He says it leads to the build-up of too much phosphorus in the planting mix, resulting in a lock-up of other vital nutrients. Byron Martin, third generation owner of Logee’s Greenhouses agrees, citing similar concerns. There are also dwarf (5-8’), petite (2-5’) and miniature varieties (1-2’). Their size makes them much more manageable in most homes and sunrooms, but the downside is that the blossoms are smaller too. My first oleander was ‘Peachblossom,’ ordered from Logee’s. Logee’s calls it a standard sized oleander, but in the above terminology used by the Richard and Mary Ellen Eggenberger, authors of The Handbook on Oleanders, it would be considered an intermediate. It’s now about 18 months old and 4 feet tall. Its pink double blossoms are about 3-3½ inches wide and have the delicate scent of talcum powder. The petal shape is reminiscent of gardenias, except much more delicate. My second plant, another “standard” variety called ‘Variegata,’ so named because its variegated leaves are edged with yellow, bloomed for the first time on New Year’s day. It’s also a pink double that smells like talcum powder, but the blossom shape is more characteristic of oleander. At Logee’s in Danielson, Connecticut these plants usually bloom in the spring and in the summer. Here in the brilliant Colorado sun, either outdoors or indoors facing south, I expect a head or two of blossoms every 4 to 6 weeks. I seem to have free-flowering varieties, but as with other flowering plants, if the genes don’t limit flowering, the amount of light will. Originally from the Mediterranean region, oleanders are ideally suited to pot culture here in Colorado. They like the hot, sunny and dry summers outdoors and the moderate, bright and dry winter indoors when heating systems are going full blast. Botanically they are Nerium oleander and are found in the dogbane family (Apocynaceae), along with plumerias, mandevillas, allemandas, adeniums, vincas and natal plums (Carissa). So they are definitely in the company of other stunning plants. Once established in the ground, oleanders are considered tolerant of ordinary droughts. Pot culture is different, though, since the roots have absolutely nowhere to go to survive. So don’t let them get bone dry. In the blazing summer heat, they will go dry rather rapidly. They also get pretty hungry. When they are actively growing, feed them once a month (maybe twice a month in the summer) with one of the more balanced fertilizer containing more or less equal parts of nitrogen, phosphorus and potassium. Grower Peter Golden likes the timed release fertilizers, such as Osmocote and Follett’s Watch Us Grow, applied according to directions. If you do decide to feed a water-soluble fertilizer, then Golden recommends a thorough leaching with water every 4th or 5th time you fertilize. It’s often said, oleanders will grow in almost any soil, but again when you grow them in pots, use a mix that will help establish a healthy root system by permitting thorough drainage. It may be best to mix your own, according to the following recipe found on the International Oleander Society website: 8-9 parts (by volume) peat-based potting mix, 1 part sand and 1 part perlite. It is always a pleasure to share plants with friends. Most oleanders root in water with relative ease, although the process can take a couple of months. This makes them child’s play to propagate. The best time to root cuttings is from late spring to midsummer. I have had success with green tip cuttings, but rooting woody stems is much more difficult. Use tip cuttings that have at least two sets of leaf nodes. As with almost all great plants, there are some negatives. First, like many other beautiful plants in our midst, all parts of the oleander plant are poisonous if ingested, including the sap. The toxins responsible are oleandrin and other glycosides. Oleander supposedly tastes so terrible that most people instantly spit it out. Please don’t try this and please don’t even think about growing oleanders if you have small children that are likely to munch on them. Even the smoke from burning oleander wood is poisonous. In fact, in areas where oleanders grow, people are routinely warned not to roast marshmallows or hot dogs on oleander sticks. Oleanders are a potential problem for pets too. My cats, though, seem to know instinctively that these plants are not good to eat and they don’t go near them, yet I’m not sure other animals would display as much sense as my two Persians. Another negative is insect pests. You would think that insects would not seek out poisonous plants for a meal, but oleanders are prone to scale, yellow, orange or green aphids and occasional attacks of spider mites. Scales can be found both on top of leaves and on the undersides, but not often on the stems. They are easily removed with cotton rounds dipped in alcohol or a toothbrush dipped in alcohol. The aphids are easily dislodged with a strong jet of water. At the rate they reproduce, you’ll need to do this every couple of days. The spider mites don’t like water either. They can be destroyed by strong jets of very warm water too, but it’s much more difficult to get rid of them permanently. Insecticidal soaps are the next line of defense, followed by horticultural oil sprays. There are two major don’ts in using horticultural oils: Never apply in full sun and never indoors. You’ll have an oil mist all over your walls, rugs, and drapes and whatnot. There is one last caveat: Always read the instructions on the container. By the way, if you get tired of the alcohol trick, you can also remove scales with horticultural oil. The oil spray suffocates the insects. Just be sure that you don’t spray so much that you also suffocate the plant! When they are grown outdoors, some people recommend rinsing off the oil after one hour to avoid damaging the leaves. By the way, I have observed that during their time outdoors, oleanders experience almost no insect problems. The beneficial insects out in the garden seem to take care of the scale and the aphids. It might be a good idea to encourage these friendly insects by not using pesticides. My oleander collection has now grown to 6 plants, including some oleanders from a hardiness experiment in Texas. They are in fact hardy to USDA Zone 7 or 8, but most likely would not survive our Colorado winters. However, it is possible they might prove to be root hardy here, if well mulched and planted in a sheltered area protected from the north and west weather. I have found oleanders rewarding because they seem to bloom so often and are relatively easy to grow in our Colorado climate. ---------- Sources of information: Eggenberger, Richard and Mary Helen Eggenberger. The Handbook on Oleanders. Cleveland, GA: Tropical Plant Specialists, 1996. (available on the International Oleander Society website) International Oleander Society website www.oleander.org. oleander pictures from oleander.org - pictures (left to right): Mrs. Kempner, Mrs. Runge, Mrs. Moody

Oleanders as Indoor/Outdoor Plants

by Paula Szilard

If you haven’t given serious consideration to growing oleanders indoors you are not alone. For one thing, they can get quite tall. The tallest varieties range in size from 12-20 feet in height, effectively limiting them to the great outdoors. The intermediate size varieties will grow anywhere from 8-12 feet tall. Growing these in pots and pruning them regularly should keep them at around 6 feet or less. In addition to frequent pruning, some people try to keep them short by feeding them chiefly with high phosphorus fertilizers intended for blooming plants. This is said to keep the vegetative growth in check, according to an article on the website of the International Oleander Society (www.oleander.org). Grower Steve Golden of Cypress Gardens Nursery in Pasadena, Texas does not recommend this practice. He says it leads to the build-up of too much phosphorus in the planting mix, resulting in a lock-up of other vital nutrients. Byron Martin, third generation owner of Logee’s Greenhouses agrees, citing similar concerns.

There are also dwarf (5-8’), petite (2-5’) and miniature varieties (1-2’). Their size makes them much more manageable in most homes and sunrooms, but the downside is that the blossoms are smaller too.

My first oleander was ‘Peachblossom,’ ordered from Logee’s. Logee’s calls it a standard sized oleander, but in the above terminology used by the Richard and Mary Ellen Eggenberger, authors of The Handbook on Oleanders, it would be considered an intermediate. It’s now about 18 months old and 4 feet tall. Its pink double blossoms are about 3-3½ inches wide and have the delicate scent of talcum powder. The petal shape is reminiscent of gardenias, except much more delicate.

My second plant, another “standard” variety called ‘Variegata,’ so named because its variegated leaves are edged with yellow, bloomed for the first time on New Year’s day. It’s also a pink double that smells like talcum powder, but the blossom shape is more characteristic of oleander. At Logee’s in Danielson, Connecticut these plants usually bloom in the spring and in the summer. Here in the brilliant Colorado sun, either outdoors or indoors facing south, I expect a head or two of blossoms every 4 to 6 weeks. I seem to have free-flowering varieties, but as with other flowering plants, if the genes don’t limit flowering, the amount of light will.

Originally from the Mediterranean region, oleanders are ideally suited to pot culture here in Colorado. They like the hot, sunny and dry summers outdoors and the moderate, bright and dry winter indoors when heating systems are going full blast. Botanically they are Nerium oleander and are found in the dogbane family (Apocynaceae), along with plumerias, mandevillas, allemandas, adeniums, vincas and natal plums (Carissa). So they are definitely in the company of other stunning plants. Once established in the ground, oleanders are considered tolerant of ordinary droughts. Pot culture is different, though, since the roots have absolutely nowhere to go to survive. So don’t let them get bone dry. In the blazing summer heat, they will go dry rather rapidly. They also get pretty hungry. When they are actively growing, feed them once a month (maybe twice a month in the summer) with one of the more balanced fertilizer containing more or less equal parts of nitrogen, phosphorus and potassium. Grower Peter Golden likes the timed release fertilizers, such as Osmocote and Follett’s Watch Us Grow, applied according to directions. If you do decide to feed a water-soluble fertilizer, then Golden recommends a thorough leaching with water every 4th or 5th time you fertilize.

It’s often said, oleanders will grow in almost any soil, but again when you grow them in pots, use a mix that will help establish a healthy root system by permitting thorough drainage. It may be best to mix your own, according to the following recipe found on the International Oleander Society website: 8-9 parts (by volume) peat-based potting mix, 1 part sand and 1 part perlite.

It is always a pleasure to share plants with friends. Most oleanders root in water with relative ease, although the process can take a couple of months. This makes them child’s play to propagate. The best time to root cuttings is from late spring to midsummer. I have had success with green tip cuttings, but rooting woody stems is much more difficult. Use tip cuttings that have at least two sets of leaf nodes.

As with almost all great plants, there are some negatives. First, like many other beautiful plants in our midst, all parts of the oleander plant are poisonous if ingested, including the sap. The toxins responsible are oleandrin and other glycosides. Oleander supposedly tastes so terrible that most people instantly spit it out. Please don’t try this and please don’t even think about growing oleanders if you have small children that are likely to munch on them. Even the smoke from burning oleander wood is poisonous. In fact, in areas where oleanders grow, people are routinely warned not to roast marshmallows or hot dogs on oleander sticks. Oleanders are a potential problem for pets too. My cats, though, seem to know instinctively that these plants are not good to eat and they don’t go near them, yet I’m not sure other animals would display as much sense as my two Persians.

Another negative is insect pests. You would think that insects would not seek out poisonous plants for a meal, but oleanders are prone to scale, yellow, orange or green aphids and occasional attacks of spider mites. Scales can be found both on top of leaves and on the undersides, but not often on the stems. They are easily removed with cotton rounds dipped in alcohol or a toothbrush dipped in alcohol. The aphids are easily dislodged with a strong jet of water. At the rate they reproduce, you’ll need to do this every couple of days. The spider mites don’t like water either. They can be destroyed by strong jets of very warm water too, but it’s much more difficult to get rid of them permanently. Insecticidal soaps are the next line of defense, followed by horticultural oil sprays. There are two major don’ts in using horticultural oils: Never apply in full sun and never indoors. You’ll have an oil mist all over your walls, rugs, and drapes and whatnot. There is one last caveat: Always read the instructions on the container. By the way, if you get tired of the alcohol trick, you can also remove scales with horticultural oil. The oil spray suffocates the insects. Just be sure that you don’t spray so much that you also suffocate the plant! When they are grown outdoors, some people recommend rinsing off the oil after one hour to avoid damaging the leaves. By the way, I have observed that during their time outdoors, oleanders experience almost no insect problems. The beneficial insects out in the garden seem to take care of the scale and the aphids. It might be a good idea to encourage these friendly insects by not using pesticides.

My oleander collection has now grown to 6 plants, including some oleanders from a hardiness experiment in Texas. They are in fact hardy to USDA Zone 7 or 8, but most likely would not survive our Colorado winters. However, it is possible they might prove to be root hardy here, if well mulched and planted in a sheltered area protected from the north and west weather.

I have found oleanders rewarding because they seem to bloom so often and are relatively easy to grow in our Colorado climate.

----------

Sources of information:

Eggenberger, Richard and Mary Helen Eggenberger. The Handbook on Oleanders. Cleveland, GA: Tropical Plant Specialists, 1996. (available on the International Oleander Society website)

International Oleander Society website www.oleander.org.

oleander pictures from oleander.org - pictures (left to right): Mrs. Kempner, Mrs. Runge, Mrs. Moody