Repot it to a smaller pot with good drainage and use a good quality potting mix, place near a window with good light or under lights. You can cut off the . Water well, let dry out some before next watering. It oldest, ugliest leaves if you want to - it should respond nicely.

I'm sort of amazed that this little plant is alive, or appears to be. There are no drainage holes in this pot, which is clearly too big and it hasn't been watered in who knows how long? Plus the recent temps at night have been around freezing??

I unpotted it and unfortunately broke that long stem in the process. I found a node with a bud on it though and put some rooting hormone on it and put it back in the pot, maybe it'll root. There were not nearly enough roots for this giant rusty pot it was in.

I'm guessing this is a wax begonia? Any way, I put it right beside the Aerogarden for now so I can keep an eye on it. A neat little project. =D

That long stem isn't necessary, should have been trimmed and used for proping as you are doing. I thihk I might put it in a plastic bag with a bit of sphagnum, rather than putting it on the pot. It is a strong looking plant,HCMC's repotting seuggestion is the way to go, begonias are basically shallow rooted. I think that pot is much too large. It's not a wax, looks more like an upright rhizomatous or shrub, not a cane either. Lucky you, it does look like a fun project and you can learn from it.