Two summers ago we divided my grandmother's begonia which she had grown for years indoors in a north-facing window - it thrived but was too big for the pot. Our divisions did well until recently; the biggest division even flowered last spring. Now, however, they are all showing similar symptoms:
Outer leaves begin to darken and dry at edges. Eventually they shrivel completely.
The new growth looks fine, but eventually it does the same thing.
We are careful not to overwater - we let the plants dry out and then give them water without letting them stand in it. They are all in north-facing windows without too much direct sunlight.
Could someone please advice us how to help our plants?
Did you move it recently? Sounds like you grew it indoors year round and it did fine for a year so I wonder what changed.
Can you move them to a sunnier window? If not you might try artificial light. How dry do you let it get? Don't let it dry out too much but don't let it stay wet either. A lot of rhizomatous are putting out new growth at this time and old ratty leaves should be or could be pinched off.
hcmcdole, thanks for your reply. No, it hasn't been moved and it has, indeed, been indoors year round. We also can't figure out what has changed!
I usually let the surface get bone dry and then water thoroughly without letting it stand in water. Once in a while, I fertilize with a diluted fertilizer. It is producing new leaves, but it's losing tons of bigger ones at the same time. My mom and I have divisions from the same original plant in separate houses; yet both have the same symptoms.
I wouldn't let it get bone dry for one thing and most rhizomatous will lose their older leaves in a year or less. Removing older uglier leaves should encourage new growth. Anyway you might try a plastic lid over the entire pot to help keep the humidity high which might help.
Here is a pot of Shamus that has some older, damaged (ugly) leaves and a flush of new growth a few days ago. I've debated on whether to keep the old leaves on for possible progation at a convenient time or remove and discard them.