In cold areas, start the tubers indoors about 6 weeks before you anticipate the last frost. Plant the tuber in potting soil, round side down, about 1" below the surface. Water well and then keep the soil moist but not soggy. Keep in a warm, semi-shady area. When all danger of frost has passed, transplant outdoors being careful not to disturb the roots. In the garden, begonias need rich, porous, well-drained soil and shelter from wind. Space 12" apart in shade or partial shade. Keep moist and fertilize at least once a month. In containers tubers can be spaced 4-5" apart. Tuberous begonias should be dug and stored over the winter. Hardy in zones 9 and 10.