Next year, you can propagate more of your favorite tuberous begonias by division. Just like a potato, the tuber can be cut into pieces containing at least one eye on each piece and planted. Dust the cut surface of the tuber with charcoal and start in peat, just like a whole tuber.
When buying new tubers, look for a firm tuber — think of the way you choose a potato: firm, not mushy with any soft spots. Pink or white sprouts, which are signs of growth, are acceptable, but avoid tubers with excessive sprouting. The sprouts will grow but won’t give you head starts — the pale, weak new shoots will probably break off or rot anyway — not grow into strong plants.
If tubers grow from seed, then why not grow tuberous begonias from seed? It’s far too late to grow tuberous begonias from seed this year. But maybe next year. For flowers this year, start now with a tuber. Seeds are as fine as dust and need very careful handling. They’re carefully dusted onto pots or flats of moist peat, and covered with a sheet of glass until they sprout. Begonias can be grown from seed in about a year.
Prices for tubers range from about $1 or $2 to about $3 or $4 each, depending on the variety and size. As with all tubers, choose the largest ones you can find for the best result the first year. The cost of tubers is not as expensive as it might seem. You can easily save them from year to year if you lift these tender tubers in the fall after the foliage turns yellow. Tubers are then gently dried and packed away in a frost-free place until another year. And well-kept tubers keep getting bigger and better every year. They’re worth saving.