Will a calla lily survive in northern Illinois winters? I did not plant this flower: several came up as volunteers when we overturned some soil.
The Gardener’s Answer
Hello, B: Calla lilies (Zantedeschia) are native to South Africa. They can be reliably grown in hardiness zones 8 and above. That being said, there are gardeners in zone 6b/7 who have their callas come back year after year. They may have a microclimate in their garden. In your case I would think you just got lucky. If I am not mistaken, I think you are gardening in USDA hardiness zone 5, which would not even be marginal in terms of hardiness for these plants. There are many reasons why this could happen; first, if you had a mild winter and the space where they are growing is close to the house where it would receive some winter protection as well as radiant heat, this would certainly help. They likely came back from the actual rhizome and not by seed. To ensure that you will have your calla lilies every growing season, you can dig up the rhizomes, let them dry, store them in a cool dark space until spring, and then replant them. You can also press your luck and see if you can get them to come back next year as well. A layer of mulch will help insulate and protect the rhizomes. Usually it is the cold, wet weather that rots the bulbs. They are a lovely addition to the garden and make for a great cut flower.