Nutrition:
The secret to Adenium nutrition is little & often. Because the plant, given ideal conditions, can grow surprisingly fast, it can utilize a lot of nitrogen and other nutrients. On the other hand, excessively fast growth is soft and susceptible to rot as well as aesthetically unappealing.
My policy with Adenium nutrition is to follow the plant's lead: maintain a low but constant level of basal nutrition and feed extra when the plant is going into a growth spurt. How much and what we give in this extra feed depends on many factors such as media, season as well as our aims regarding that plant: a variety that we are bulking up on and rapidly propagating will get much higher levels of feed than one being grown as a flowering pot plant. Similarly, heavily bearing mother plants require high levels of specific nutrients to give the best seeds.
Fertilizer Suggestions:
The following is our way of feeding our Adeniums and is reasonably successful. No doubt it can be improved upon and we ourselves keep trying to get better results all the time. Also note that it works with our media, under our conditions and with our systems and would need to be modified for other situations. A more detailed article on plant nutrition FERTILIZING POT PLANTS can be viewed at hoscoindia.com. For details on nutritional problems, see NUTRITIONAL PROBLEMS.
Organic Slow Release:
Since we start with a low nutrient media and do not add a nutrient charge to it, we need a source of slow release fertilizer. The various coated materials like Osmocote etc are either not available here or are too costly. What we use, with surprisingly good results is pelleted chicken manure. A table spoonful or two as a topdressing perks up the plants no end. A small amount is added to the media as well while mixing.
Pelleted chicken manure is commonly used as a top dressing in Taiwan. The growers assured me that no chemical (inorganic) fertilizer is used at all.
I saw this being used in Taiwan where it's used exclusively by some of the best growers and their media is almost all stone chips.
Chemical Fertilizers:
We now use a complete liquid fertilizer containing all Macronutrients (Nitrogen, Phosphorus, Potassium, Calcium, Magnesium and Sulphur) as well as all Micronutrients (Iron, Manganese, Copper, Zinc, Boron and Molybdenum). This is used at alternate watering at an EC of 1.5mS/cm and is giving us better results than our old system of using only Calcium and Potassium nitrate in the liquid feed. The exact ratios of the nutrients can be varied and we are juggling them to find the best combinations for our conditions. This would also depend on the growth stage and season