During the first few years, young plants grow rapidly if provided with liquid fertilizer. Fertilizer every two weeks during the spring, then a slow release fertilizer in early summer, and again in early Fall. Liquid fertilizer can be used during the dry winter months when temperatures stay above 80 degrees. As they mature, you can cut back dramatically on the liquid fertilizer, or even eliminate it. However, the application of slow release fertilizer should continue throughout the life of the plant.
To develop a large swollen base, a good quality fertilizer is needed, which will also increase flowering. Use a phosphorus-based fertilizer, not too high in nitrogen. Don't ever apply fertilizers directly onto the roots and always water first slightly to avoid root burn and leaf drop.
Desert Rose responds amazingly well to food so use plenty of time release pellet food. Growth will be much faster and flowers will be more prolific as well.
For feeding during spring and summer, use a controlled release fertilizer, as well as organic fertilizer such as fish emulsion. Controlled, slow-release fertilizers are carefully worked into the soil. Allow houseplants to 'rest' during the winter months; stop fertilizing in late October and resume feeding in late February.
General macronutrient deficiency with yellow foliage, fallen lower leaves, red tinting and reduction in size of new leaves. These plants have been neglected and not fed for several months.
Nitrogen (N): Deficiency leads to yellowing and subsequent dropping of lower leaves, small leaves and flowers and general lack of robustness. Typically a plant on low nitrogen levels will have naked stems with tufts of small, stiff leaves at the ends. Excess will lead to soft, green rapid growth with big leaves and increased internode spaces. Nitrogen levels can be used to control growth, along with phosphorous, and can be used in two forms- ammoniac and nitrate. Nitrate creates more compact growth.
Potassium (K): A deficiency will lead to edge burn of lower leaves followed by leaf drop. Excess K competes with Ca and Mg in an antagonistic relationship- if the Mg is high, the plant should be supplemented with Calcium to prevent problems.
Phosphorus (P): a deficiency will lead to poor growth and red coloration of lower leaves. An excess of phosphorus will lead to excessively vigorous growth when combined with high Nitrogen. Stems tend to shoot up and the plant looses form rapidly. Keeping Phosphorus low will help to maintain a compact plant. Monopotassium phosphate or phosphoric acid may be used to when needed to boost growth.
Magnesium (Mg): Normally this is found in sufficient quantity in water and does not need to be added as a fertilizer. It has an antagonistic relationship with Potassium and Calcium, both of which we must add to counter high Magnesium levels.
Calcium (Ca): Deficiency symptoms include leaf tip burn, very small, often abortive, blackened new leaves and tip death. Flowers drop and seed pods develop typical "blossom end rot".
Boron (B): Extreme Boron deficiency halts all new growth in this Adenium that has been pruned back hard. A drench with Solubor is effective in solving this problem.
Deficiency symptoms are similar to Calcium (distinguished by the fact that Calcium tends to affect the leaf tip and Boron the base of the leaf): leaves deform with corrugations (as if the midrib is too small for the leaf), aborted tip growth and deformed seed pods with corky streaks. Flowers tend to split up. If necessary, add boron in the foliar spray at regular intervals.
Copper (Cu): Deficiency symptoms include small, cup shaped new leaves, flowers very much smaller and with distinctly pale coloring and small, twisted seed pods with corky skin. This effect on the seeds pods sounds identical to Boron deficiency but is substantially different in character. A spray of copper fungicide will clear the problem. A drench with Copper Sulphate at at 25gms per 1000 Liters of water also works well for several months to a year.
Though flower bud abortion is common in Copper deficiency, sometimes the flower will hold but open small with rudimentary petals and very pale color.
Zinc (Zn): Deficiency normally occurs on large plants in old media, especially if the seed load is too heavy. New growth slows and internodes become very small, leaves become smaller, narrow and often curve to one side. Seed pods will curve inwards, yellow and open up before aborting. The immature seeds inside show black necrotic areas. Often affect one of a pair of pods.
Iron (Fe): Iron deficiency chlorosis is typical and easily cleared up with foliar iron spray along with pH control of the media. Iron chlorosis is often a sign of root damage or death- knock out the plant and check the roots- often the media will be degraded and soggy with little or no new roots. Another reason is an excess of other micronutrients like Cu or Zn - overdoing the drench will show up as Iron deficiency chlorosis.