Several species of Begonia leaves will root in water, but not the annual wax Begonia. Do you know which one you have? Is it a tuberous Begonia?

Hi. Thanks for posting. Yes, it is a tuberous Begonia.
MacThayer

Tuberous begonias grow easily from stem or leaf cuttings. Young growth works best and cuttings should be taken early in the year.

The plant grown from the cutting needs time to grow itÂs own tuber before it goes dormant the next fall, so the earlier the better. Tuberous begonias donÂt root well in water, except for the smaller stemmed types like the caudex forming types and B. sutherlandii.

Most tuberous stem cuttings will start directly in potting mix (I prefer sand). They may look wilted initially but most will eventually root and recover.

ItÂs best to keep them in shade until they have rooted. Leaf cuttings should be started as you would rhizomatous begonias.

i do my cuttings like that in a soda bottle, and they do great!! leave the lid off though, uhhh the first time i didn't and mold like you wouldn't believe!! LOL