Caudiciform Begonia and Pelargonium questions

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?

The Begonia dregei looks like it needs soil that has much better drainage than the one you have it in. It should have about 1/2 soil without peat in it (I use cactus soil) mixed with 1/2 pumice (or perlite if you can't get pumice). You are overwatering it and it looks like some stems are rotting. The caudex on these plants hold water and you should only water if the soil is dry. The Pelargonium would grow more if you move it into a somewhat larger pot. Move up a size or so. BUT it needs the type of soil I mentioned above and don't overwater it either. Too dry is better than too wet!

I agree with Nancy. Always err on the side of dry.
I like you gave it some systemic insecticide. I have had a lot of trouble with mealy bugs in the past until I started using some.
I have been using semi-hydroponics (s/h) for many (most really) of my caudiciforms with good results. There are lots of threads here that explain what it is and how to use the method. I recommend looking into the technique to see if it might be something to try.
Good luck with your plants.
Helen

Thanks Nancy and Helen. I will repot both. The Begonia I had put in cactus mix, with 1/4 Perlite, because I thought the cactus mix would already drain well. You can't see the perlite because that was about the 3rd one I repotted like that, and had not liked how the perlite floated, so the top 1/4 inch was plain cactus mix. I have now bought a bag of pumice, I like it much better.
I am now reading "Pachycaul and Caudiciform Plants" by de Vosjoli, a 300+ page book(I am also a bookaholic), and have gone back through many old threads on this forum. I've caught the bug! Only a systemic insecticide can rid me of it and I have no desire to poison myself so I will just have to learn to live with it. The bookoholism I have mostly dealt with by using the library, but for rare specialized books like these, often self published by fanatics in Australia, the library does not have them, and Barnes an Nobles does not even sell them! The internet is a strange and wondrous thing that can keep you up past your bedtime, cause packages to arrive on the porch, and mysteriously run up your VISA bill.

Mimi, as Helen suggested Semi Hydroponics is great for caudiciform plants. I have quite a few in it also. Cactus soil is okay for cacti but, even with cacti, I add pumice to the mix. All these plants like a nice open loose planting mix so the roots don't rot.
1st plant is: Pachypodium saunderi; 2nd one is Euphorbia bupleurifolia; 3rd one is Euphorbia viguieri


This message was edited Jul 4, 2013 3:40 PM

Nice plants Nancy. Do you know the name of that last Euphorbia?

I have added the names on the post. The E. bupleurifolia is a slow grower and loves the S-H. Every couple waterings I feed them lightly and they do great. They get morning sun here in AZ, but in WA they can probably take more.

Thanks Nancy. My oversite. It must be my glasses! ;-)

Helen: I edited my post AFTER you asked me about the name! No oversite on your part!

Two begonias that have spent summer outside (lots of rain and heat).
1. B. Richardsiana
2 & 3 B. Dregei 'Tweedle Dee'
Both pots are about 7". I find Richardsiana really easy to grow and to propagate. Inside during winter let it dry out then water.
Tweedle Dee is another story - Declines during winter inside then comes back in warm weather. My plant room is set at 62 degrees so perhaps it would like it warmer during winter.
In both cases use half n half MG cactus and regular potting soil.

Hi everyone-your plants all look great. My Pelargonium whateveri var. whoknowsus is doing fine, looks quite lush and happy. The Begonia is still struggling, I cut out part that seemed rotted. If it does not survive my chilly moist winter I might try again, the Tweedle Dee is lovely.

I love the begonias. They don't do well here in Phoenix because just too hot at night in summer!

Beautiful plants garden guy.

Thanks!!

My begonia did not survive, it was too late to save it, but I may try again someday if I ever run across one again. My Pelargonium dasycaulon (I got help with the ID on the Plant Identification forum) is doing just fine. I had suspected it is a winter grower/summer dormant species, and this was confirmed once I knew the name. Here it is today. I actually water it quite a bit now, and it seems to really appreciate that. Before I was sure it was a winter grower, I restricted water in the winter.
p.s. I changed my DG name to Pistil, from mlmlakestevens, and DG has changed it in all the old posts.

I am glad you are enjoying your plants Pistil. Have you tried eBay? You might find what you are looking for.