Somewhere I read that with tuberous begonias, when two stalks have grown from the tub or, you could gently rock the non-dominate one from the tubor (like with a loose tooth) until it comes off and then after dipping in rooting hormone, put this in moist mix and it would take root. Has anyone tried this? Bought box of 20 tubors at "Sam's and would love me to increases this number to 30 or 40.
I've never done this myself but I'd go ahead and give it a try with one and see how it goes. If it roots OK then you know you can do it with the rest.
I would wait until the stalks are about 2 1/2 to 3 inches then try to root the stalk in a Forsythe pot to assure that it does not rot from too much water or dry out. Careful not to injure the tuber by taking part of it with the stalk. That might allow disease into the tuber. Be sure to bleach, then rinse the pots well. Use fresh vermiculite. Pictures maybe? Jerry
Stalks are about 4" tall. Trip to Lowe's for more vermiculite. Need more potting mix anyway. Will send pics before I try it.