Begonia woes

I have a few Begoni that are looking terrible. I don't know what exactly is happening with them, be it over watering, under watering, or what. I am beside myself as what to do for them! I have had most of these plants several years & others longer. This is the first time I have seen them do this. Of the 6 I have in the house, only one is doing OK. the rest are in different stages of this "moult" (sp) Like birds do). They all get watered the same as they always have. Once a week. The leaves just keep drying, shriveling & droping off. HELP! What do they need oh great BBG? (Big Begonia Guru)
Here's the Rex that is shedding the fastest, These two leaves both have the dry spots on them, soon they will be on the counter.
Bj

The other pics are a beefsteak that used to be just beautiful but is limping also. This is in a different room than the first Rex.

and a Luxurians that is doing the same.

This is another Rex in the same room with the Beefsteak, it is nearly bald, except for the leaves at the end of the stems.
Any ideas? I don't see any bugs or gnats or nothin.
Bj

Bj, just answered your dmail too, but one thing to consider is dry air/warm temps in the house. Can you describe the area you are growing in? The first rex photo looks like it might be turning brown on the edges due to humidity (lack of) or salt burn from fertilizer. Do you use city or well water? (I ask because boron does this to my plants as well)

The last photo looks like one you might want to propagate. You can cut the end with the leaves off, pot it up in your mix, and put it in a ziplock bag until it roots. In the mean time, the stem you left behind will start to put out new leaves . Some times rhizomes just get long and leggy like that.

Many of mine are looking ratty right now too.

Has your heating been different this year from previous years? I know CA has had an unusual cold spell recently so I'm guessing your heat has been on longer than you've ever experienced. If this is the case, you probably have dried out the air - very low humidity. I added gravel to my pans this year and it seems an uphill battle to keep water in the pans let alone the pots due to the furnaces running. Put your plants in a plastic bag with some stakes to hold the bag off the leaves and see if that perks them up.

Bj, I had the same problem with 12 of my rexes, and trays of pebbles and water did little to help this particular group with the lack of humidity. I put them into ziplock bags under lights, in my warm furnace room, and they are making a grand recovery. When they come out this spring I will code their tag so in the fall I will know to sort them out and take them straight to the basement for winter storage.

Tussee

Yes, we have been heating like crazy. We do heat primarily with wood. I do have 2 pots with water in them on there at all times. It may be the heat. I know the Rex out in my studio, which is not heated with wood & kept fairly cool is doing great. Thought I may just move all of these out there. I will cut off some of those stems & plant them as you have said, move them out to the studio too. Bring in my cactus, LOL! Thank-x so much for coming to the rescue! Bj

I've seen the same phenomenon on many begonias. Most of them made a recovery when I moved them the "terrarium". For the rexes this has failed though.
This "terrarium" is not a terrarium in its true sense, thus the quotes. It's a wooden construction with thick foil on its floor and heating mats under the pots and light tubes on top right under the transparent coat.
This 2 x 1 x 1 m construction is not as airtight as a real terrarium can be and thus does not completely eliminate temperature fluctuations and air movement. But it is large enough to be home to not just small begonias.

this is so funny because I took pics of one of my begonia's this morning and was going to ask for help on it....so all of you that have provided suggestions were actually helping two birds with one stone....Thank You....a pic of mine in distress....Deb