Hi Deborah,
I really cannot give you a definitive answer about fertilizers. I had used several different ones throughout the past 15 months of my first time growing adeniums (experimenting)...rooting hormone liquid, bonemeal, fish emulsion/seaweed, MG, Mg for orchids, Triple 16, 10-20-20, Osmocote 14-14-14, Bayer's 3 in 1. Also, I had changed media and up-potted several times. At one point I overfed and got too fast a growth that I had to prune many of them down.
That said, it's not only the fertilizer that promotes good large growth...the soil media is a major component as well. Around 8 months old, the two large adeniums were up-potted (yet again) into a very aerated media: 7 parts perlite, 1 part potting soil, 1 part peat moss, 1 part vermiculite, and grown in plastic panterra bowls. They doubled in size over the past 6 months!
Hope this helps.
Kadie
