Answer: Calla lilies (Zantedeschia) grow from rhizomes (thickened roots) and can grow into clumps if left undisturbed for a few years. You can divide your calla's during the dormant season, after the leaves have died down and the plants are resting. Dig the rhizomes and divide by breaking apart the mass. You'll be able to see individual rhizomes once the soil has been brushed or washed away. Replant, setting each rhizome 2" deep. Since callas are dormant during the winter months, rain won't have any effect on them, as long as your soil drains well (puddles don't remain on the surface for any length of time).
Q&A Library Searching Tips