Thank you hc;

The sphagnum moss is definitely moist: confirmed by fingers and moisture meter. I check it sometimes.

Other than that, I'm afraid to leave the lid on the terrarium/greenhouse open for long periods because I'm still fighting gnats. When they find an open terrarium it becomes their new favorite place to live.

That said, what should I do now, in this situation? Just leave it alone? The environment seems right, according to what I've read — if it's just stressed, maybe it'll come back around?

This is a puzzle. You seem to be doing everything right (I've had one for 3 years and just mailed off a start which appeared on a decaying leaf), My guess is that it is too warm if you are sure it is not too wet. My plant grows in an upright small terr. on the edge of the light garden, has never bloomed. The room temp. seldom gets as high as 70 F., most begonias are actually cool growers. I've moved most of my canes into my greenhouse for the summer, the nights are about 50 F, and they appear to be thriving because the light is so much better for them there.

I took a look thru the Thompson Guide. Begonias have a range of 52 to 72 degrees F, the lower range should be considered a night temperature. She discusses variations of temperature, she suggests too quick a change of temperatures might be harmful to some of the sensitive types. Maybe that is what has happened.

Thank you Woebegonia! I just moved it again, hopefully this won't really cast it into the throes of death. It's now in a large glass jar right next to the air conditioner, so I can open the top and let air in and hopefully keep it cooler. It's such a beautiful plant; too bad it's such a pain! Same with Pavonina.

I must be on a roll here. I found an old article by a botanist who wrote an article about begonias for the ABS magazine. He said 75 degrees F is too hot for begonias, and that there is no transpiration above that temp. In other words, they will be goners.

Yikes! Is that the case for all begonias? I have a Autumn Embers that's doing just fine out in open air... But I guess hybrids like that might be more acclimated to human temps?

Could be. If you think about it the semps and tuberhybrida survive outdoors and hot summers and can still look good going in to Fall. The species must be the touchy ones, I have pavonina and can't grow it outside its container, same for Bs. xanthina, irridescens, even little foliosa does better in a container. I think most of my species are in containers, until I find out otherwise. Containers take up a lot of room, but I start any new plant in them just in case.

Woebegonia said:

" I found an old article by a botanist who wrote an article about begonias for the ABS magazine. He said 75 degrees F is too hot for begonias, and that there is no transpiration above that temp. In other words, they will be goners."

Yep, I'm calling BS on that statement. Our temps in summer are usually mid 90's and sometimes get to 100. Begonias seem to have not got the word as they thrive.

I am keeping my iridescens indoors though mainly due to its size (not get lost among the giants). B. xanthina did a lot better outdoors than inside for winter as well. Anyhow the growers in Florida would have a field day with this information as the growers at Harmony (and PHOE when it was open) had species in hot, humid conditions and they are the largest I've ever seen. It feels like a real sauna in those greenhouses and in July and August it would make most of us faint.

Woebegonia what kind of container do you have Pavonina in?

Just read up on Sarawak where chlorosticta is a native of. The website said the temps ranges from 73 to 89 on average and as low as 68 and high as 97. Humidity stays high since it is so wet and usually exceeds 68% (such precise numbers).

A lot of begonias can be found at the entrances to caves as well where it is usually a little cooler and even more humid. Been in some caves in Belize in February and they were very HUMID.

Right now pavonina is in a small glass container as it has been cut back. Eventually it will reach fruit ripening bowl size and need to be cut back again because my growing area gets so crowded. Same size for Bs. decora, soli-mutata, sudjanae, versicolor, , rajah, goegoensis. However to start small keep an eye out for glass double boilers. You can remove the bands and handle and have good medium sized growing areas. B. chlorosticta has never been a biggie for me, it is on the edge of the lights which is probably why it has never bloomed. It is in a dbl boiler sized pot but also sitting inside a 10 gal. fish tank with some others. One gal. glass jugs, if you can find them, make good containers. I have Bs. exotica and benitochiba in one each, they survive best there with very reduced light. There is a clear top on the fish tank, I should have said. Actually I grow small species begonias too, way too many of everything.

ya the 75 degrees statement is flat false: Now I will agree most begonias do better at cooler temps (ie, 65-80 degrees.. all types), however, many of mine outside under trees with filtered light did fine in this last heat wave we had here in South Texas( 105+ degrees 3 days in a row). I have more trouble growing begonias IN the greenhouse, which never gets above 90 degrees even on the hottest day.. totally stumped. I have failing begonias( all types) in my GH, but thriving ones out in the yard IN The heat.. baffled. I have over 250 different species, hybrids, etc. Funny, I never had the desire to do a terrarium, but now I am in love with them! My 2 cents :)