Cheryl, adeniums are quirky to say the least. I also have adeniums that remain small...some kind of genetic thing going on I think. Sooo...what I have done with these is to change out their media into a grittier mix (keeping the root ball intact so as not to stress the plant further), and placed them in ceramic bonsai containers. They are my special little ones and I love them!
These adeniums are all about the same age. (Magnify the pic to see the other two.) As you can see, the three little ones had remained small so I transferred them into ceramic pots in gritty mix. They are doing quite well...in fact, one of the little ones looks like it's got tiny flower buds growing out..
