Hello Nikki!
Keep in mind the Adenia and Adenium are not related, despite the name similarity and presence of a caudex.
I stumbled into caring for an Adenia glauca at the greenhouse where I volunteer. I started out knowing absolutely nothing, and have had trouble finding information about care. I've killed every Adenium I've been near, but the Adenia has been doing well for several years. The following information is just from my personal experience.
Adenia glauca grows as a vine. It will not turn into a shrubby Adenium shape.
Mine goes dormant in Winter. I stop watering and fertilizing, and cut the vines back when they dry. I gradually resume watering with warmer temps, longer days, and new growth in Spring.
It's potted in an extremely fast draining gritty mix with very little organic material.
It likes lots of water in summer, a good soaking 2-3x per week. It gets no water when winter dormant.
It does great in long, hot 90+ degree days in summer. It is situated so the caudex itself is partly shaded, but the vines grow up to the heat and light. The caudex has stayed green, and is slowly enlarging.
Leaves were extremely chlorotic when I took over care. I upped the fertilizer, added some soil sulfur, sprayed with chelated iron, and generally fussed around with it for several years. Chelated iron spray did green them up. I then read that they are heavy feeders when they are actively growing. This year, I started fertilizing every week with Miracid, 1 tsp per gallon. Bingo, no more chlorosis and strong viney growth. It even flowered this year. (It's a girl!)
I don't know of anything, other than good general care and hot weather, that would encourage a larger caudex.
I would be very interested in any information or recommendations from others!
Here's a snapshot from earlier this year, when it was just starting its spring growth. Stems eventually reached 4+feet long, vining up to the rafters.
