tba,

Check to see if the stems are rotting or rotted. If so then the roots may be dead. You should be able to root any healthy stems with a couple of top leaves attached in a porous mix (a good potting soil with a liberal amount of perlite would be good). Just move it to a shady area while rooting though and maybe provide a humidity tent. Keep moist but not wet.

If the stems are healthy looking then move the pot to a shadier area and cut back on watering until the plant revives. You can also cut wax begonias back somewhat hard, fertilize lightly, and they should put out new growth soon.

Severe heat can stress wax begonias to death especially in full afternoon sun. Try 'Dragon Wings' for full sun, instead.

I would treat wax begonias as annuals at the end of summer unless it is something special.

Butch

Thanks for the advice, Butch. This might be a dumb question, but how can I tell if the stems are rotting or rotted? I assume if they don't look green and firm, that might be a good indication that they're rotting/rotted.

The stems could be black and dry looking if already rotted or mushy if starting to rot. It could also be burned and dried out from too much sun and heat and not enough water. Going by your description it sounds like you were pouring the water to it, so I'm guessing rot.

Butch