Dividing and Transplanting Calla Lilies
Calla lilies grow from horizontal root stems called rhizomes. If after a two to three years your clumps of calla lily have multiplied and the rhizomes (roots/bulbs) become overcrowded they may stop flowering. When this happens it's time to divide them so they'll have more breathing room and space to grow. Fortunately, calla lilies are very easy to divide and transplant to different areas of the garden or give to friends.
When To Divide Calla Lilies
The time to divide calla lilies is after they have flowered and their foliage has turned completely yellow. This is usually in late summer or early fall, before they've gone into dormancy.
How To Dig The Calla Lily Rhizomes
Use a shovel or a pitch fork to dig in a circle and loosen the soil around your plant and it's rhizomes (bulbs/roots). The rhizomes look like pieces of a ginger root. As you move in a circle around the plant, push the blade deeper into the ground to a point underneath the cluster of rhizomes. The rhizomes will be growing just a couple inches under the soil. Then lift the plant and the cluster of rhizomes. Cut the foliage back to about 2 to 3 inches and then lay the rhizome clusters on the ground in the shade.
How To Divide The Rhizomes
Colder Climates - Where calla lilies are not winter hardy
If you are in a colder region where calla lilies are not winter hardy you'll need to dry the rhizome clusters. Brush the dirt off the rhizome clusters and place them in a shady area for several days before dividing and storing them. When they have dried, use a sharp knife to separate the rhizomes from one another. You don't have to separate the rhizomes exactly where they connect but each piece of rhizome needs to have roots growing from it.
Warmer Climates - Where callas are winter hardy
If you are in a warmer region where calla lilies survive the winter you can divide the rhizomes right away. It's a good idea to count the potential new plants you'll have before dividing them. This way you'll know how many new holes or how much space in a new garden bed you'll need to prepare for transplanting them. You can pre-prepare the new area(s) by digging and turning about 2 inches of composted organic matter into the soil, then raking the soil surface smooth. this way you can immediately transplant the calla rhizomes to their new home after having divided them. If you will be planting them close together in a garden bed, make sure to provide at least 6 inches of space between plants. Then plant the rhizomes about 2 inches deep covering them with your soil mix or top soil.
After transplanting water the planting bed gently. You'll want to water enough to keep the soil always moist.