Caudiciforms: Caudiciform Begonia and Pelargonium questions, 1 by Pistil

Pistil wrote:
I am new to this fascinating group of plants. On impulse, I bought a Begonia dregei. (picture #2) It seems to have synonyms B suffruticosa and B richardsiana. It forms an underground caudex, and is from eastern South Africa, which I think is the summer rainfall area. It keeps dropping it's leaves. I thought it was too dry, in too small a pot so I potted it up from a 2" pot with about a tablespoon of soil to this clay pot, and put systemic insect killer on it although I saw no pests. I have kept it pretty dry, watering once a week, but maybe too dry? Or maybe it wants to go dormant?
I also got a Pelargonium grown by Fleetfoot and Foulweather. (picture #1) It has a penciled label that I think says Pelargonium dasycoulon, and describes it as "seed grown, caudexed". This one I can't find anywhere. It seems to match a description of P. dasyphyllum, which is deciduous in summer, from South Africa (thus probably from the winter-rainfall area), or possibly it is P. dasycaule, which I found mentioned in an old book. I did not pot it up and it seems quite happy in it's 2" pot, and I am watering it once a week. It has new growth.
Now what do I do? Anybody know?