Yes, calla lilies can be planted outside, but their survival depends on your climate. They are winter hardy in USDA zones 8 through 10, and must be overwintered indoors in colder areas.
That graceful, trumpet-shaped flower you see in bouquets and garden centers looks like it belongs in a warm greenhouse. It’s easy to assume calla lilies are too delicate for the outdoor garden, but they can actually thrive in beds and borders with the right approach.
The short answer is yes, you can plant calla lily outside. The longer answer involves matching your local climate to the needs of this tender perennial from the genus Zantedeschia. Your zip code and local frost dates determine whether they bloom year after year or need to be dug up each fall.
Start With Your Hardiness Zone
Calla lilies are not true lilies. They grow from rhizomes and are classified as tender perennials by extension services. Their outdoor survival hinges entirely on your USDA zone.
In zones 8 through 10, calla lilies are winter hardy. You can plant them directly in the ground and they will return each season with proper care. In zones 7 and below, they are typically grown as annuals or lifted from the soil each fall for indoor storage.
Knowing your zone is the single most important factor before you put a calla rhizome in the ground.
Why Climate Is the Deciding Factor
Many gardeners assume a plant sold in a greenhouse belongs indoors forever. Calla lilies break that rule, but only within a specific temperature range. Here is what determines their outdoor fate:
- Tender Perennial Status: Calla lilies can survive mild winters outdoors. A hard freeze turns their stems to mush, so regions with freezing winters must treat them as annuals or store them inside.
- USDA Zones 8 to 10: In these warmer zones, plant calla lily rhizomes outdoors in spring about 4 inches deep. Choose a spot with damp soil and a bit of afternoon shade for the best performance.
- Zones 7 and Below: Gardeners in colder climates can plant calla lilies in the garden or in containers. They will bloom from July through the first frost, but must be dug up before a hard freeze.
- Bloom Time: Rhizomes planted in spring produce flowers from midsummer into fall. This long bloom window makes them worth the extra effort in cooler regions.
Understanding your growing zone is the first practical step toward enjoying these elegant blooms outdoors.
How to Plant Calla Lilies Outdoors
Once you know your zone, the actual planting process is straightforward. In zones 8 and warmer, place the rhizomes in the ground about 4 inches deep after the last frost date. In cooler climates, you can start them in pots a month or two before moving them outside.
The University of Minnesota Extension discusses exactly this process in its guide on how to Plant Calla Lily Outside, noting that for best performance they should go into the garden or containers in the summer. When transplanting a potted calla into the ground, dig a hole slightly wider and deeper than the root ball and set the top of the root ball level with the surrounding soil.
Outdoors, calla lilies typically reach 1 to 3 feet tall, making them ideal for the middle of a border or grouped in large containers.
| Feature | Recommendation | Notes |
|---|---|---|
| Planting Time | Spring, after last frost | Start indoors 1-2 months early for a jump |
| Depth | 4 inches | Rhizomes should be fully covered |
| Spacing | 12-18 inches apart | Depends on size of the rhizome |
| Sunlight | Full sun to partial shade | Afternoon shade preferred in hot zones |
| Hardiness | USDA Zones 8-10 | Considered a tender perennial |
| Mature Height | 1 to 3 feet | Ideal for borders and containers |
Winter Care for Cold Zones
For gardeners outside zones 8 to 10, a little fall preparation guarantees your calla lilies return. The process is straightforward and takes only a few minutes per plant.
- Wait for the First Light Frost: Allow frost to kill the tops of the plants. This signals the rhizomes to enter dormancy. Do not let them experience a hard freeze, which turns the stem to mush and damages the rhizome.
- Dig and Dry the Rhizomes: Lift the rhizomes from the soil. Shake off excess dirt and remove the dried stems. Place them in a warm location around 60°F to dry for 2 to 3 weeks.
- Store for Winter: After drying, store the rhizomes at 45 to 55°F for the rest of the winter. A basement or garage that stays cool but above freezing works well.
This simple routine mimics the dry season calla lilies experience in their native habitat and keeps the rhizomes healthy for replanting in spring.
Understanding Hardiness Zones
A solid understanding of your hardiness zone removes all the guesswork. Per the Winter Hardy Zones 8-10 fact sheet from Iowa State University, calla lilies are rhizomatous perennials that thrive outdoors in those warmer regions without winter intervention. In zones 7 and below, they can be grown as annuals or overwintered indoors.
The term tender perennial means the plant may or may not survive winter depending on cold severity. In zones 8 through 10, a deep layer of mulch can provide extra protection on colder nights. In zones 5 through 7, lifting the rhizomes is the safer choice.
If you prefer a simpler approach, grow calla lilies in containers. Pots allow you to move the plants to a frost-free garage or basement when temperatures drop.
| USDA Zone | How to Plant Calla Lily Outside | Winter Care |
|---|---|---|
| 8 to 10 | Directly in ground in spring | Hardy; mulch heavily for protection |
| 5 to 7 | In ground or containers | Dig up rhizomes before hard freeze, store indoors |
| 3 to 4 | Best in containers for mobility | Store pots in frost-free garage or basement |
The Bottom Line
The answer to whether you can plant calla lily outside is a confident yes, provided you match your care to your climate. Gardeners in zones 8 to 10 can enjoy them as reliable perennials, while those in cooler zones can still enjoy months of blooms by lifting the rhizomes each fall. The effort of digging and storing them is small compared to the reward of their elegant flowers.
If you are unsure about your local frost dates or need specific advice for your soil, your local county extension office is an excellent resource for hyper-local guidance from experts who know your climate best.