One of the easiest plants to bring inside for the winter is the canna lily. You don’t even need a special greenhouse or growing light system to do it. Canna Lilies are considered a perennial but in colder regions act more like an annual. They require you to lift the rhizomes from the soil so they don’t freeze during harsh winter conditions.
But overwintering only applies to certain hardiness zones. Overwintering is very common amongst certain bulb plants, like Dahlias and Begonias.
If you do have to overwinter your canna lilies, how do you do it? Keep reading to find out what hardiness zones these tall flowering perennials need to overwinter in and how to do it. Ready to learn more? Let’s dig in!.
Cannas are stunning tropical plants that add vibrant color and texture to gardens. Their large, banana-like leaves and brightly colored flowers create a tropical oasis in backyards and gardens. While cannas are technically tender perennials, they can be overwintered in colder climates with proper care and storage.
Overwintering cannas allows gardeners to enjoy these tropical beauties year after year. It saves time and money since you don’t have to purchase new rhizomes every spring. By following some simple steps, you can successfully overwinter your cannas and have them bursting with life when warmer weather returns.
When to Dig Up Cannas for Overwintering
The key to overwintering cannas is timing You need to dig up the rhizomes once the plants have gone dormant after the first hard frost This usually occurs in late fall between the first week of October through November. Here are some signs your cannas are ready to be dug up
- Leaves and stems have turned brown or black from frost damage
- Plants look dried out and faded
- Hard frosts have occurred in your area (below 28°F/-2°C)
Don’t wait too long before digging up the rhizomes. If left in freezing ground for too long, the water content in the rhizomes can expand and rupture the cells.
Ideally, you want to dig up the rhizomes within 1-2 weeks after the foliage sustains heavy damage from frost This gives the rhizomes time to go dormant while ensuring they aren’t damaged by prolonged freezing temperatures
How to Dig Up and Divide Rhizomes
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Cut back the dead foliage a few inches above the ground. This makes it easier to access the rhizomes.
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Using a spade or garden fork, dig around and under each rhizome clump. Gently lift them out of the soil.
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Shake off excess soil but don’t wash the rhizomes. Some remaining soil helps retain moisture.
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Cut rhizome clumps into smaller sections, ensuring each division has 2-3 growth buds or “eyes.”
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Inspect the rhizomes and discard any that are diseased, hollow, or mushy. Healthy rhizomes are firm and turgid.
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Allow divisions to cure in a warm, dry spot for 2-3 days before storing. The curing process helps wounds callous over.
Storing Cannas Over the Winter
Cannas need to be kept dormant in a dark place with temperatures between 40-50°F (4-10°C). Good storage options include:
- Unheated basement, cellar, or garage
- Crawl space under a house
- Insulated shed or outbuilding
Avoid storing cannas in a heated space or anywhere temperatures will dip below freezing. This can cause them to rot or sprout prematurely.
Traditional Storage Methods
Cannas can be stored bare root or packed in slightly damp peat moss, vermiculite, sand, or wood shavings. Packaged rhizomes retain moisture better than bare roots. Place the divisions in cardboard boxes, plastic bins, or breathable bags. Store in a cool area until spring.
Simpler Garbage Bag Method
For those short on time, rhizomes can be stored in heavy-duty garbage bags:
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Place rhizome divisions in a sturdy black trash bag. Squeeze out excess air and loosely tie the top.
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Store in a cool area around 45°F. The dark bags prevent sprouting.
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Check occasionally and remove any mushy rhizomes to prevent rotting.
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Keep the rhizomes sufficiently moist by misting the inside of the bags. Don’t oversaturate them.
This simpler method works well for overwintering cannas. The dark bags keep rhizomes dormant while the plastic retains humidity. Just monitor moisture levels and remove any rotting rhizomes promptly.
Checking for Viability & Rotting
Check stored rhizomes 1-2 times during winter. Look for signs of rotting like soft, mushy textures and mold. Rotten rhizomes should be immediately discarded to prevent disease spreading.
To check viability, scratch the rhizome surface with your fingernail. Live rhizomes will be hardy and firm. Discard any that feel hollow or collapsed as they likely won’t sprout in spring.
Ideal rhizomes are firm, turgid and have visible swollen growth buds. Viability drops if rhizomes shrivel or desiccate during storage, so maintain humidity levels.
When to Plant Cannas Again in Spring
Cannas can be planted back in the garden once nighttime temperatures rise above 55°F. This is usually around the same time as your last expected spring frost.
For added insurance against frost damage, wait 2-3 weeks after your area’s average last frost date before planting. You can also get a head start by planting rhizome divisions indoors 4-6 weeks before the last frost.
When planting cannas in spring, follow these tips:
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Prepare garden beds with rich, moist soil. Cannas thrive in fertile, well-draining conditions.
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Plant rhizomes 2-3 inches deep and 12 inches apart. Eye buds should face up.
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Water thoroughly after planting and provide 1-2 inches of water per week during growth.
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Add a balanced fertilizer once new shoots appear. Fertilize regularly according to package directions.
With proper planting depth, watering, fertilization, and sunlight your cannas will be flowering beautifully again in no time!
Key Steps for Overwintering Cannas: A Quick Summary
Follow this checklist for successfully overwintering your cannas:
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Dig up rhizomes in early fall after foliage is killed by frost.
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Shake off excess soil and divide large clumps into smaller sections.
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Allow divisions to cure for 2-3 days in a warm, dry spot before storing.
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Pack in slightly moist peat moss or vermiculite. Or simply place in plastic bags.
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Store in a cool 40-50°F location like a basement or unheated garage.
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Check periodically for rotting. Discard any diseased or mushy rhizomes.
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Replant in spring once night temperatures remain above 55°F.
Overwintering FAQs
Here are answers to some frequently asked questions about overwintering cannas:
Can I leave cannas in pots over winter?
Yes, you can overwinter cannas in pots. Move the pots to a sheltered spot and allow the foliage to die back after frost. Prior to winter, remove dead leaves and add mulch to insulate the soil. Store the pots in an unheated garage or cellar over winter.
Do I need to water overwintered cannas?
You shouldn’t need to actively water overwintered cannas. But it’s important rhizomes and media remain slightly moist. Check moisture levels 1-2 times during winter and lightly mist with water if needed to prevent desiccation.
What temperature is too cold when storing cannas?
Avoid exposing stored rhizomes to temperatures below 40°F (4°C) as this can freeze and rupture cell walls. Freezing damage causes rhizomes to rot. Ideal overwintering temperatures are between 40-50°F (4-10°C).
Can I grow cannas as annuals?
In very cold climates, cannas can be grown as annuals. Plant rhizomes in spring after frost danger has passed. Dig up the rhizomes in fall to overwinter or simply discard them after first frost and replant new ones next year.
How do I know if stored rhizomes are still alive?
Check for firm, turgid rhizomes with visible growth buds. Live rhizomes feel hardy when pressure is applied. Discard any that are soft, hollow, collapsed or extremely lightweight as they have likely died over winter.
Enjoy Lush Cannas Year After Year
With a little winter preparation, gardeners in cold climates can overwinter cannas and enjoy these beautiful tropical plants season after season.
By digging up and storing the rhizomes properly each fall, your cannas will return in full force the following spring. Just be sure to time it right, store them in cool yet above-freezing conditions, and replant once the weather warms up again.
Overwintering By Hardiness Zone
In USDA zones 3–7, you will need to pull them out of the ground and plant them again in the spring. If you decide to leave the rhizomes in the soil during freezing conditions, they will not regrow. You will have to purchase or replant lifted rhizomes in the spring.
If you choose to grow your canna lilies in a container then your job is even easier. Simply, bring the container into a cool, dry area for the winter. It’s that easy! If you want to move them to a different pot, just dig up the rhizomes from the old pot and put them in the new pot springtime.
Zones 8 and above are in luck, you can leave them in the ground year-round. You can always put straw or mulch over the plant to protect it even more from possible frost if you are worried.
Rhizomes can easily be stored in a basement, garage, or cool, dry space. They should be in total darkness and no heat. I prefer to place them in a large heavy-duty black trash bag in my insulated garage.
You have worked hard all season to keep your these tall blooming beauties full and lush. It would be a shame to lose them to improper overwintering.
Why Overwintering is Necessary
Rhizomes are susceptible to frost and are recommended to be dug up and placed indoors for the winter.
Canna lilies produce thick, fresh rhizomes near the soil surface. The rhizomes are sensitive to freezing conditions. Rhizomes are made up of mostly water and when exposed to freezing soil conditions the water expands and causes the plant cells to burst. When the plant cells burst, the rhizomes die and are unable to produce sprouts in the spring.
If your region experiences freezing temperatures, you should dig up the rhizomes and store indoors overwinter. If you leave them in the ground over the winter, they will mush up and not grow back in the spring or summer.
It’s hard to say if your area will get frost if you are on the border of zones 7 and 8. As we already said, you can cover the plants with straw or mulch if you don’t want to dig them up or don’t have time. This should be enough to protect the rhizomes from a light frost or two.
If you live somewhere that doesn’t get frost, you’re lucky! They can stay in the ground and grow back in the spring. If you want to move them or just add more, dig them up in the fall and put them somewhere cool and dry until spring.
When the temperature gets frosty and the leaves turn yellow and black, you can start digging them up.
If you live in zones 3–7, the best time to dig them up is when it starts to frost and the leaves start to fall off. When the frost hurts your canna lilies, the leaves will change from yellow to black and start to fall to the ground.
Let your canna lilies experience one to two frost before considering lifting from the ground. Freezing temperatures initiate dormancy which is needed to successfully store the rhizomes. Don’t let them sit in the ground too long because the frost will kill them. You don’t want to start digging and find out nothing survived.
If you are growing in containers, wait until the first frost. Once the foliage has turned yellow, you can begin the overwintering process.
Then move the container to a cool, dry place until spring. This is convenient because it doesn’t involve digging and curing. Make sure your soil is dry before placing it into storage. Wet to damp soils can initiate germination and lead to rotting rhizomes.
If your plants start to sprout in the container during winter, move to a cooler area. Always monitor your containers for sprouts. If you catch sprouting soon enough, there is a high chance of saving the plants.