Zantedeschia, commonly known as Calla Lilies, are grown from thickened underground stems called rhizomes. Transplanting them in the fall is the most advantageous time for the move, as this timing aligns with the plant’s natural life cycle and minimizes stress.
The preference for fall transplanting is tied to the Calla Lily’s need for dormancy following the summer growing season. As the plant finishes blooming and temperatures cool, the foliage naturally yellows and dies back. This signals that the plant is channeling energy from the leaves down into the rhizome for storage.
Transplanting a plant while it is dormant significantly reduces the risk of transplant shock. The ideal window is in the late summer or early fall, after the blooms have faded but well before the first hard frost. Moving the rhizomes during this resting phase allows the plant to settle without the immediate demand of producing new flowers or foliage.
Preparing the Rhizomes for Relocation
Once the foliage has yellowed, signaling dormancy, prepare the plant for lifting. Use sharp shears to cut the remaining foliage back to within one or two inches of the soil surface. Removing above-ground growth prevents water loss and helps the plant focus energy into the underground storage organ.
Carefully lift the entire clump from the soil using a garden fork, working outside the perimeter of the stems to avoid damage. Gently shake away the soil to expose the rhizome mass. Inspect the rhizomes for signs of disease, such as soft or discolored areas, which should be trimmed away immediately with a sanitized knife.
If the clump is dense or propagation is desired, the rhizomes can be divided. Look for natural constrictions or buds, known as “eyes,” and separate the rhizomes, ensuring each new section has at least one eye to sprout next spring. After cleaning and division, allow the rhizomes to air-dry in a cool, shaded spot for a few days to help the exterior skin toughen before replanting.
Replanting and Site Selection
The success of the transplant depends on the selection and preparation of the new location. Calla Lilies thrive in full sun in cooler climates, but require afternoon shade where summer heat is intense. Selecting a spot with rich, well-drained soil is important, as the rhizomes will rot if they sit in saturated conditions over winter.
Incorporate organic matter like compost or aged manure into the planting area to improve soil structure. The new planting hole should be wide enough to accommodate the rhizome comfortably. Place the rhizome with the pointed growing tips, or eyes, facing upwards, and cover it with three to four inches of soil.
Gently firm the soil around the rhizome to remove air pockets. Space individual rhizomes about 12 to 18 inches apart to allow for future growth and air circulation. Immediately after replanting, give the area a single, deep watering to settle the soil, but avoid subsequent heavy watering since the plant is dormant.
Post-Transplant Winter Protection
After the fall transplant, providing adequate winter protection is important, especially in cooler USDA Hardiness Zones (Zone 7 and below). While some varieties, like Zantedeschia aethiopica, are resilient, colorful hybrid Calla Lilies are often tender and require insulation. Protection guards the shallowly planted rhizomes against repeated freezing and thawing cycles that can heave them out of the ground.
Once the ground begins to freeze, apply a generous layer of mulch over the replanted area. A three to six-inch layer of straw, shredded leaves, or wood chips serves as an excellent insulator. This organic material helps maintain a consistent soil temperature, preventing extreme cold from reaching the rhizomes.
In climates where the ground freezes deeply or remains frozen for extended periods, heavy mulching may not suffice for tender varieties. In these regions, a more reliable method is to lift the rhizomes after the foliage dies back and store them indoors in a cool, dry, frost-free location until spring. The protection strategy should be tailored to the specific hardiness zone and the variety of Calla Lily being grown.