Canna is one of several tropical garden plants that can be grown in northern climates with specialized care. Technically, the roots of cannas are rhizomes, but they are commonly referred to as bulbs because the root structure closely resembles that of a classic plant bulb. In warm climates (USDA hardiness zones 8 to 10), canna bulbs can be left in the ground over winter, and the plants perform reliably as perennials, coming back year after year. However, north of zone 8, the bulbs will die if they spend winter in the ground. In colder climates, the plants are either treated as annuals and discarded at the end of the season, or the bulbs are dug up and stored for winter and replanted the following spring.
Storing the bulbs is fairly quick and easy, depending on how many you have to dig up. However, they require some monitoring while theyre in storage.
Canna lilies are known for their beautiful, tropical-looking flowers that bloom all summer long. Their lush foliage and bright blooms add vibrant pops of color to gardens even during the hottest parts of summer when other flowers start to fade. But what should you do with cannas when cold weather arrives? A common question gardeners have is whether you can dig up the bulbs (which are actually rhizomes) before the first frost hits, or if it’s better to leave them in the ground.
Reasons to Dig Cannas Early
There are a few potential benefits to digging up your canna rhizomes early
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Get a head start on spring planting – If you dig up the rhizomes in fall you can clean them up, divide them, and store them properly over winter. This allows you to get them replanted again as soon as possible early the next spring
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Avoid damage from hard frosts – Extremely frigid temperatures can damage rhizomes left in the ground. Digging them up early guarantees they won’t get hit by an early severe freeze before you get them into storage.
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Prevent rotting – Wet, cool soil in fall can cause rhizomes left in place to rot. Getting them dug up prevents rot issues from setting in if they are left in the ground too long into cooler autumn weather.
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Make space for other plants – If you want to plant flower bulbs, veggies, or other cold weather crops in the same bed as your cannas, you’ll need to dig up the cannas first to make room for the new plantings.
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Propagate new rhizomes – Digging up cannas in fall allows you to divide and propagate additional new rhizomes. More rhizomes means more cannas for next year!
Reasons to Wait Until After Frost
While early digging has some potential advantages, there are also good reasons many gardeners choose to leave cannas undisturbed in the ground until after the first frost:
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Let foliage die back naturally – Frost kills back the foliage, making the plants look unsightly. But leaving them be allows the leaves to die back naturally on their own time.
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Give rhizomes more time to store energy – Like other bulbs, cannas build up food reserves in their rhizomes late in the season. Leaving them in place longer allows them to stockpile more energy for next year’s growth.
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Avoid shocking rhizomes – Digging cannas up early can stress and shock them. Letting them stay put avoids this shock to the rhizomes.
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Use foliage as natural mulch – Once frost hits, the dead foliage provides natural insulation right where it lies as it breaks down. This mulch layer helps regulate soil temperature around the rhizomes.
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Delay prep work until later – Leaving cannas in place longer pushes back the work of cleaning, dividing, and storing the rhizomes until later in the season. You can relax and enjoy fall before tackling the bulbs!
The Ideal Time to Dig Cannas
Most gardeners find a happy medium by digging cannas 2-4 weeks after the first light frost hits their area. A couple light frosts are enough to kill back the foliage and signal to the rhizomes it’s time to go dormant. But bulbs left sitting in cool, wet soil for too long after this point risk rot setting in.
Digging cannas during this 2-4 week window after light frosts allows the foliage to naturally die back, while still getting bulbs out of the ground before they are threatened by rot. It prevents shock or damage from an early severe freeze yet avoids leaving them in too long.
Here are some signs cannas are ready for digging in that ideal 2-4 week post-frost window:
- Foliage has turned brown and limp after light frosts
- Stems feel rubbery and easily separate from rhizomes
- Soil is cool but not frozen solid yet
- Most other garden plants have already died back for winter
How to Dig Up Cannas
Digging up cannas properly ensures you get the healthiest rhizomes for storing over winter and replanting next spring:
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Wait for foliage to brown after light frosts. Don’t dig until frosts have done their job naturally killing back the leaves.
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Use a garden fork to gently loosen soil and lift out rhizomes. Avoid nicking or scratching bulbs with tools.
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Carefully knock off excess soil. Gently shake or rinse rhizomes to remove soil but don’t damage the roots.
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Cut back dead foliage to 2-3 inches. Removing foliage prevents rotting in storage but leave a stub to protect growth buds.
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Discard any mushy or rotten rhizomes. Healthy rhizomes feel firm. Toss any that are soft or smelly.
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Allow rhizomes to dry and cure for a week. Air curing toughens skins and prevents rot in storage.
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Wrap and pack cured rhizomes for storage. Place in newspaper, peat moss, or vermiculite then store in a cool, dark spot around 45°F to 55°F.
Storing Cannas Over Winter
The proper storage environment is critical to successfully overwintering cannas. Aim for conditions that are:
- Cool (40°F – 55°F)
- Dark
- Dry with moderate humidity
- Well-ventilated to prevent mold
Basements, unheated garages, and crawl spaces often provide suitable storage conditions. Make sure rhizomes are packed in dry peat moss or newspaper, not touching each other or crammed too densely in boxes. Check them periodically over winter and discard any that show signs of rotting.
With proper storage care, most gardeners successfully overwinter 80% or more of their canna rhizomes.
Ready to Replant in Spring
Getting a head start on digging up cannas allows you to get rhizomes properly cleaned, cured, and stored so they are ready to go for spring planting. In early spring, you can divide them to propagate additional bulbs. This ensures you’ll have plenty of vigorous cannas raring to be replanted as soon as it’s warm enough.
While cannas can technically be left in the ground over winter depending on your climate, most gardeners have much better success carefully digging and storing the rhizomes. This guarantees your cannas will survive the winter cold and return bigger and better than ever next year.
What Is a Rhizome?
Rhizomes are plant stems that grow below the ground, not above the ground. Rhizomes have multiple functions, such as sending out new shoots and using nodes to send out roots into the soil to perform asexual reproduction by vegetative propagation. Often roots grow from the bottom part of the rhizome while shoots grow from the upper portion of the nodes. The thickness, size, and growth patterns of rhizomes vary greatly from plant to plant, yet the basic functions and characteristics are the same.
When to Dig Up and Store Canna Bulbs
Dig up canna bulbs for winter storage in the fall after the foliage has died back but before deep frost has arrived. Most gardeners dig up their bulbs immediately after the foliage has been killed by the first light frosts in fall or early winter. Light surface frost wont penetrate down to the buried bulbs, but a deep frost can ruin them.
Replant the bulbs in spring after the ground has fully thawed and all danger of frost has passed. This usually means late spring for most gardeners.
The digging and storing technique for cannas will work for many tropical plants that grow from bulbs, tubers, corms, or rhizomes. These include elephant ears, blood lilies, caladiums, and dahlias.
Dividing and Potting Stored Cannas
FAQ
Can canna bulbs survive a freeze?
Canna plants are not frost hardy although their root system or rhizomes will survive a frost if they are well protected.
When to pull up canna lily bulbs?
Firstly and before you dig up your Canna bulbs you must wait until after the first killing frost in the fall. With your shovel in the ground far enough to go under the bulb, gently lift the shovel and pull the bulb out of the ground.
Do cannas need to be dug up in the fall?
Digging cannas in the late fall is necessary to overwinter cannas in zones 6 and colder. Not sure of your zone? Here is a great interactive map to help.Apr 7, 2018
What happens if you don’t dig up canna bulbs?
However, north of zone 8, the bulbs will die if they spend winter in the ground. In colder climates, the plants are either treated as annuals and discarded at the end of the season, or the bulbs are dug up and stored for winter and replanted the following spring.
How do you dig and store canna bulbs for winter?
Dig them up after the first frost, rinse the dirt off with lukewarm water, let them dry inside someplace warm for about a week, wrap them individually in brown paper bags or newspaper, then put them in a container in a dark and dry corner of your basement or heated garage.
When should you dig up Canna bulbs for winter storage?
Dig up canna bulbs for winter storage in the fall after the foliage has died back but before deep frost has arrived. Most gardeners dig up their bulbs immediately after the foliage has been killed by the first light frosts in fall or early winter. Light surface frost won’t penetrate down to the buried bulbs, but a deep frost can ruin them.
Can you dig up Canna bulbs before Frost?
Yes, you can dig up canna bulbs before frost. Canna bulbs should be dug up when the leaves turn yellow or brown and begin to die off, usually late in the summer to early fall before the first frost. When harvesting the canna bulbs, use a fork or shovel to dig deeply around the plant to loosen the soil and keep the bulbs intact.
When should you dig a Canna plant?
Wait to dig the cannas up until after a frost has killed back the foliage. Once the foliage is dead, carefully dig around the canna bulbs. Remember that canna bulbs can multiply rapidly over the summer, so you will want to start digging a bit further out from where you originally planted the canna.
When should Canna bulbs be buried?
Canna bulbs should be dug up and stored for the winter in the fall, after the leaves have died back but before it gets really cold. Most gardeners dig up their bulbs as soon as the first light frosts kill the leaves in the fall or early winter. Light surface frost wont penetrate down to the buried bulbs, but a deep frost can ruin them.
Do cannas need to be frosted before digging?
Dig clumps of cannas after the first frost. It is not necessary for cannas to be frosted prior to digging, but it is recommended. It serves as nature’s last signal for the bulbs (rhizomes) to go dormant. After digging the clumps of bulbs, remove soil by shaking or rinsing with water. Divide clumps into 3-5 eye bulbs (rhizomes).
How do you dig up Canna bulbs?
Just about any digging tool can be used to dig up canna bulbs. But because the bulbs are typically planted 4 to 6 inches deep, a shovel or garden fork will often be the best option. Keeping the shovel blade or garden fork away from the plant stalks, dig down and raise the bulbs out of the soil.