Adenium Page
Introduction
This genus offers a great potential for development into some spectacular hybrids. With regional forms and newer species being brought to cultivation, the genetic variation is tremendous. I believe we will see many new colors before the end of the century and even perhaps some highly ornamental cultivars developed in the process.
Cultivation of Adeniums
The cultivation information is subdivided into 6 parts. Each subheading will try and best explain the how to's and don't's of Adenium culture. Please e-mail me with specific questions at any time. See below for information regarding about sending e-mail. The basic culture is somewhat like that of orchids. Just remember a small pot with excellent drainage is a must. Do not over-pot and allow the plants to dry out between heavy waterings.
Pot/Containers
I like plastic pots with generous drain holes on sides and bottom. I sometimes make additional drain holes with a thick drill bit scattered throughout the bottom. Otherwise terra cotta, cement, or hard-cast plastic pots are fine too! But ample drain holes is a must. Adding coarse crock, styrofoam peanuts, big stones, coarse charcoal chunks, or even wood chips to plug drain holes. See Soil/Media next for details.
Soil/Media
The best media (here in Hawaii) is equal parts black cinders, redwood potting mix and perlite. I sometimes add pumice to spread out media. This media works best in areas where ample water and watering is available. After you add the materials for drain-hole covering, add some pure cinders to hold bottom drain holes in place. Then place your plant (just slipped out from its previous pot) in the center. Pot up a 10cm potted plant to a 15cm pot, for example and maintain the same level or just slightly deeper. Even if your plant in the 10cm pot is overgrown, DO NOT REPOT it to a pot bigger than 15cm. Add the soil mixture around between the pot and original media. Do not remove the old media from the rootball as this will set the plant back a few months. On more established plants, I like to add some granular fertilizer to the soil at planting time. See next suject for Fertilizers/Fertilizing. If you potted them up on a warm sunny morning, do water them to allow settling of soil. Otherwise, water tomorrow morning.
Fertilizers/Fertilizing
To make your plants develop a large swollen base/trunk, they require a good quality fertilizer. It is very fortunate that the same fertilizer requirement for swelling up trunks is also used to increase flowering. Please use an organic source fertilizer or one that is low in salts. Preferably, no manures or ones too high in nitrogen. The middle number should be the highest. Ones that I like, if they are available are MagAmp 7-40-6, Osmocote Timed Release 18-18-18, and Nutricoat. Just add a small amount, and follow label instructions. Never add fertilizer at the root tips! Always allow a cushion of soil for safety between the roots and fertilizer granules. I also liquid feed during the warm months as a booster to keep growth active and help produce healthy reserves for the future. I especially like Peter's Soluble fertilizer given as often as a dilute soultion once per week. A diluted rate would be about a third or fourth of what is recommended on label instructions. Never liquid feed when a plant is thirsty. Always water them slightly to avoid serious root burns and leaf drops. I would also advise not to wet leaves, as adeniums can sometimes burn in bright light when fertilizer salts are present on their leaves. If Peter's isn't available, use any good commercial orchid soluble fertilizer (NOT Miracle-Grow)!
Light
Adeniums need bright light if they are to flower. Most hybrids and species start blooming in the spring when the conditions are warm and days start to increase its length. Many continue blooming through the fall and winter (in warmer climate zones). Light quality is very important. Bright filtered light is best. In areas of too high light intensities, more shade may be necessary, but in areas where light is not as burning, plants may be kept outdoors unprotected. Please note that the caudex (the swollen base trunk) is very susceptable to sun scalding. Protection by a smaller shrubby succulent growing at the base of the pots will help shade the trunk. I especially like the smaller shrubby crassulas, and aeoniums as their root system is tame and somewhat non-invasive against the bigger adeniums. This added succulent also helps use up excess water in areas where the adenium's root system doesn't penetrate. The main trunk is centered with the majority of the roots below the caudex line. Its rare that adeniums will use the upper third of their soil and often this area serves like a mulch (one that is not needed by the adenium). See Water/Watering in the next topic for more details.
Water/Watering
Adeniums like a neutral to hard water source. Acidic water tends to sour the soil too fast and may cause root rot. To find out what your water is, check with your water supply for specific pH for your area. In Hawaii, most of our ground water is stored in coral lined lens' where it is naturally higher in pH. Water that is too high in pH can restrict fertilizers from being absorbed, so somewhere just above neutral is desirable. Water plants preferably in the early mornings (still dark is fine too), and allow them to drink up throughout the day. Watering can be done daily to every few days. Initially, water your potted plants based on their weight. If the plant seems heavy, do not water. As they become drier (with all other properties in order, i.e. drainage, sunlight, container, etc.) check their weight and add water so that the soil is well wetted and excess water drains from the pot base. This draining will allow harmful salts to leach freely. Never allow your plants to sit in a saucer of water. Pots may be kept in saucers AFTER they have been drained from their pots. Only you can judge when a plant requires water. Never allow your plants to dry out too often as this causes them to go into early dormancy. Keep them active and growing by providing them with all the essential necessities. Many plants simply never get enough water to grow, less alone, flower! I feel that water is of the utmost importance in growing healthy adeniums.
Pests/Problems
Although highly toxic, many adeniums fall prey to sucking insects and mites. I like to use a systemic insecticide when treating for sucking insects. Most sucking insects are associated with ants and if you suddenly have a sucking insect problem (aphids, scales, mealies, white fly), you most likely have an ant problem. Treat the sucking insects first. Use a Systemic insecticide that contains Di-Syston. Avoid chemicals that also list some form of oil, or xylene solvent. As this alone will kill or burn your sensitive adeniums. I like brands such as Marathon (a systemic granule, you just add to your soil directly), Orthene WP (a wettable powder spray). Marathon works well over a period of time where Orthene needs a secondary treatment a few weeks later. Always use complete care and caution when spraying or handling chemicals and follow label instructions. Mites are pests that usually appear during hot and dry periods. Only a miticide will kill mites. Check with your local garden store for available chemicals. Spraying on all the newest growths and under the leaves are a must for complete control. A repeated spraying shortly after the first is usually recommended to prevent reinfestation. All plants must be sprayed even though the pest may not be evident. As mites can hide/hibernate while their food supply is being unavailable and return without warning as soon as the chemical is gone.
