Calla lily, also known as arum lily, is not a true lily. It belongs to the genus Zantedeschia which originates from South Africa. The huge, flower-like spathes of the calla lily are now coming in a lot of different colors, making it a more popular house plant as well as a garden and patio plant.
Calla lillies flower from early to late summer on sturdy upright stems. They look nice because they have pretty leaves. The broad, bright green leaves are often speckled with white or silver. You can store the rhizomes, or fleshy roots, of most calla lilies over the winter and plant them again in the spring. The exception is white arum lily (Zantedeschia aethiopica) which is hardy outside in mild areas.
Watch out for confusion with the hardy pond plant bog arum (Calla palustris). Calla palustris needs to be grown in shallow water at the edge of a pond, even though the name and white flowers may sound alike.
With their elegant, trumpet-shaped blooms and lush tropical foliage, calla lilies make a stunning addition to gardens and containers. To keep your plants healthy and flowering abundantly, periodic division is sometimes required. But when is the optimal time to separate and replant calla lily clumps?
An Overview of Calla Lily Growth
Calla lilies are rhizomatous perennials with thick underground stems called rhizomes. The rhizomes store nutrients and energy to fuel new growth each year. Mature plants produce a cluster of rhizomes that give rise to multiple stems and leaves.
Callas bloom in summer and go dormant in fall or winter depending on your climate. The foliage dies back entirely until new growth resumes in spring. The plants thrive in zones 8-11, but the rhizomes can be overwintered indoors in cooler climates
Signs It’s Time to Divide
Calla lilies only need dividing every 3-5 years. More frequent division isn’t recommended as it prevents the rhizomes from reaching full size.
Watch for these signs that your calla lilies are ready for division:
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The clumps look overcrowded with decreased flowering
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The plant’s center dies out and leaves only appear around the edges.
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Flower size and number diminishes over time.
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You want to propagate more plants from existing rhizomes.
When to Divide Calla Lilies
Calla lily division can be done in either spring or fall. Here are the pros and cons of each season:
Spring
Pros
- Warmer weather encourages quick establishment.
- No need to store rhizomes over winter.
- Brighter blooms the first year after dividing.
Cons
- Risk of disturbing new sprouts and injury to frozen ground.
- Must wait for soil temperatures to warm up sufficiently.
Fall
Pros
- Plants are dying back, so it’s easy to locate rhizomes.
- Avoids interfering with new spring growth.
Cons
- Cooler temperatures slow the division recovery time.
- Must dig up and store rhizomes until spring planting.
Step-By-Step Guide to Dividing Callas
Follow these simple steps for successful calla lily division in either spring or fall:
1. Prepare for Division
Pick a cool, cloudy day to minimize transplant stress. Water the lilies thoroughly a day or two before dividing. Have new pots and potting mix ready for replanting divisions.
2. Lift the Rhizomes
Carefully dig around and under the whole clump to lift it out with minimal damage. Knock off excess soil. Remove and compost the old foliage.
3. Break Apart the Rhizomes
Gently pull or twist apart the rhizome mass, making sure each division has roots and growth buds attached. Use a sterilized knife to slice chunks where needed.
4. Allow Divisions to Dry
Place the divided rhizomes in a shady spot for 1-2 days until the cuts callus over. Dust with sulfur powder to prevent rotting.
5. Replant Divisions Properly
Bury the rhizomes 2-3 inches deep and 8-12 inches apart in enriched, well-draining soil. Water thoroughly after planting. Apply balanced fertilizer monthly.
6. Provide Winter Care (If Needed)
In cold climates, dig up rhizomes after fall dividing and store in peat or vermiculite at 45-55°F over winter. Replant outdoors after the spring frost danger passes.
Caring for Callas After Division
Here are some tips to help your divided calla lily plants recover quickly:
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Allow plenty of time to re-establish before resuming fertilizing.
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Provide bright filtered sunlight and consistent moisture during the first year post-division.
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Stake heavy flower stems that flop over, especially on newly planted divisions.
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Remove spent flowers and yellowing leaves regularly to boost recovery.
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Watch for snails, slugs, and other pests attacking stressed divisions.
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Don’t divide again for at least another 3-4 years after splitting the rhizomes.
Dividing Calla Lilies in Pots
You can also divide container-grown calla lilies in early spring. Knock the plant out of the pot and proceed as usual. Then replant divisions in containers with drainage holes, using fresh potting mix. Water thoroughly and place in bright, indirect light.
If rhizomes get overcrowded again, transplant the entire plant into a larger container rather than dividing again so soon. This allows the rootball to continue expanding for maximum flowering.
Alternatives to Division
Instead of dividing calla lily clumps, consider these options to propagate more plants:
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Take stem cuttings in summer, root in water or potting mix. Plant out in fall.
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Allow offsets to form naturally around the base. Dig up and replant when a good size.
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Start new plants from seed (if seed pods form) for different genetic diversity.
Revitalize Overgrown Calla Lily Plantings
Periodically dividing calla lilies keeps them flowering vigorously and prevents overcrowding. Targeting spring or fall based on your climate allows the newly divided rhizomes time to recover before going dormant or blooming again. With proper care after dividing, callas will quickly regain their dramatic presence in your garden.
How to plant calla lily (Zantedeschia)
Calla lily grows from thick rhizomes or fleshy roots that are sold when dormant in winter or spring. Ready-grown plants can be bought in spring and summer, often when in full flower.
Buy in the winter or spring and plant 8–10 cm deep in a good, peat-free multipurpose potting compost to grow from rhizomes that are dormant. Either pot up and start into growth indoors for earlier flowers, or plant outside after the frosts. Plants that were grown indoors need to be “hardened off” or acclimatized to the outdoors by being left out for longer and longer periods of time.
If you want to grow calla lilies in the ground, make the soil better by adding a lot of well-rotted compost or a special soil conditioner. Space plants 30-45 cm apart.
Growing calla lily (Zantedeschia): problem solving
Calla lilies are easy to grow and mainly trouble-free.
Aphids may be a problem, particularly on plants growing indoors. Check the undersides of the leaves often, and keep an eye out for honeydew on the ground below the plant. This is made by aphids and other pests. There are many ways to get rid of aphids, but if you catch them early, many times just squishing them by hand is enough.
Dividing Calla Lilies
FAQ
What month do you divide calla lilies?
When can you split lilies?
What time of year do you transplant calla lilies?
Do calla lilies multiply and spread?
When should you divide calla lilies?
The best time to divide calla lilies is in the spring or fall, when the plants are dormant. In warm climates, you can divide calla lilies in the spring after the last frost. In cooler climates, it is best to divide them in the fall after the foliage has died back. Dividing calla lilies is a relatively simple process. Here are the steps:
How do you divide a calla lily?
Dividing calla lilies is a relatively simple process. Here are the steps: Dig up the calla lily plant. Use a shovel to carefully dig around the plant, being careful not to damage the roots. Remove the foliage. Once the plant is dug up, remove the foliage by cutting it off at the base. Separate the rhizomes.
When should I plant calla lilies?
Plant calla lilies when the risk of all frost has passed. Check your frost dates and use these times as a guide for planting. Calla lilies are actually rhizomes, and they form bulb shapes on the rhizome as they mature and multiply. Calla lily rhizomes are very easy to divide.
Should I replant calla lilies in the fall?
Dividing during the fall also gives your new plants some time to establish themselves before the following spring. Dividing and replanting Calla Lilies in the spring means the plant may not be able to grow a new root system and establish itself before the hottest parts of summer roll around.
Should I Divide and transplant calla lilies?
Or, in some cases, you may need to divide and transplant your Lilies because the clump is overcrowded. Separating Calla Lilies can rejuvenate the plant and make it healthier. Whatever the reason, it’s simple to divide and transplant Calla Lilies.
How do you replant a calla lily?
Separate the rhizomes. The rhizomes are the fleshy, underground stems of the calla lily plant. Use your hands or a sharp knife to separate the rhizomes into individual pieces. Each piece should have at least one eye, which is a small bump that will grow into a new plant. Replant the rhizomes. Replant the rhizomes in well-drained soil.