Introduction
There is a specific kind of magic in watching cannas bloom throughout the heat of summer. Their bold, tropical foliage and vibrant flowers often become the centerpiece of the garden, standing tall when other plants begin to fade. As the air turns crisp and autumn arrives, many gardeners look forward to the rewarding task of "tucking in" these beauties for their winter nap. It is a satisfying ritual that marks the end of a successful season and promises even more color for the following year.
At Longfield Gardens, we want to help you preserve that tropical flair year after year. Understanding when to dig up canna bulbs—which are technically called rhizomes—is the most important part of keeping them healthy during the cold months. This guide is designed for home gardeners who want clear, practical advice on timing and technique. We will cover the visual signals your plants give you, how weather affects your schedule, and the best way to handle these fleshy roots so they stay strong until spring.
By following a few simple steps, you can ensure your cannas survive the winter and return even bigger and better next season. Timing is everything when it gets late in the year. Getting the schedule right means you won't lose your plants to a deep freeze, and you'll give them the best chance to store energy for their next big show.
The Importance of Timing
When it comes to cannas, timing is the difference between a successful harvest and a lost plant. These are tropical and subtropical plants that thrive in warmth. They do not have a natural "off switch" that tells them to go dormant based on the calendar alone. Instead, they rely on environmental cues to tell them when it is time to stop growing and start resting.
The most critical cue is the first frost. While many garden tasks feel like they should be done before the cold arrives, cannas actually benefit from a bit of a chill. In most regions, you should wait until the first light frost has nipped the foliage before you reach for your shovel. This frost usually turns the bright green or burgundy leaves into a dark, wilted brown. While it might look a little sad, it is actually a vital signal for the plant.
Why Wait for Frost?
Wait for the frost to blacken the leaves because it tells the plant that the growing season is officially over. When the foliage dies back, the plant stops putting energy into making new leaves and flowers. Instead, it sends a final "burst" of energy down into the rhizomes stored underground. Think of this as the plant filling up its gas tank for the long winter ahead.
If you dig the bulbs up too early, while they are still in full growth mode, they may not have stored enough nutrients to survive months of dormancy. On the other hand, if you wait too long—until the ground itself freezes solid—the ice crystals in the soil can damage the fleshy tissue of the rhizomes. This can lead to rot or death. The sweet spot is the window of time between that first leaf-killing frost and the first hard freeze of the soil.
Observing Your Local Weather
Since every garden has its own microclimate, the exact date to dig will change every year. One year it might be late October, and the next it might be mid-November. The best approach is to keep an eye on your local forecast. When you see "frost advisory" or "freeze warning" in the news, you know it is almost time.
If you live in a region where frost comes very late or not at all, you can still dig your cannas once the foliage begins to yellow naturally as the days shorten. However, for the vast majority of gardeners in the United States, the frost-blackened leaf is the most reliable "start" button for the digging process.
Key Takeaway: The best time to dig canna rhizomes is immediately after the first light frost kills the foliage, but before the ground freezes. This ensures the plant has stored maximum energy for winter.
Identifying Your Gardening Zone
Before you start digging, it is helpful to know if you actually need to. Whether or not you have to dig up your cannas depends entirely on your USDA Plant Hardiness Zone. These zones are based on the average annual minimum winter temperature in your area.
Zones 8 and Warmer
If you live in Zone 8, 9, or 10, you are in luck. In these warmer climates, cannas are generally considered hardy. They can stay in the ground all year round. In Zone 8, it is a good idea to add a thick layer of mulch—about 4 to 6 inches of straw, wood chips, or shredded leaves—over the planting area. This acts as a blanket, protecting the rhizomes from the occasional cold snap.
Zone 7: The Transition Zone
Zone 7 is the "maybe" zone. In many years, cannas will survive a Zone 7 winter if they are planted in a protected spot, such as near the south-facing wall of a house. However, a particularly harsh winter can still kill them. Many gardeners in Zone 7 choose to dig up their most prized varieties just to be safe, while leaving others in the ground with heavy mulching as a test.
Zones 3 through 6
If you live in Zone 6 or colder, digging is a requirement. The ground in these areas freezes deep enough to reach the rhizomes and turn them to mush. For gardeners in the Midwest, Northeast, and mountain regions, the "dig and store" method is the only way to enjoy the same cannas year after year.
| Region Type | USDA Zones | Action Required |
|---|---|---|
| Warm / Tropical | 8 to 11 | Leave in ground; mulch in Zone 8. |
| Moderate | 7 | Dig for safety or mulch heavily. |
| Cold / Northern | 3 to 6 | Must dig and store indoors. |
Preparation Before Digging
Once the frost has turned your canna leaves brown, you can begin the preparation process. You don't need to rush out the very next morning, but you should aim to get the job done within a week or two.
Cutting Back the Foliage
The first step is to remove the dead growth. Use a clean pair of garden shears or a sharp knife to cut the stems back. Most experienced gardeners leave about 2 to 4 inches of the stem attached to the rhizome. This small "handle" makes the rhizomes easier to manage and helps you see exactly where the plant is located as you dig.
Clearing the Area
Remove any mulch or debris from around the base of the plants. This gives you a clear view of the soil surface. Cannas grow outward in a creeping fashion, so the clump of rhizomes under the soil is likely much wider than the stems at the surface. Knowing where the edges are will help you avoid "stabbing" the rhizomes with your shovel.
What to do next:
- Monitor the weather for the first frost of the season.
- Check your USDA zone to confirm if digging is necessary.
- Gather your tools: a garden fork or spade, a sharp pair of shears, and some labels.
- Wait for a dry day if possible, as it makes cleaning the soil off the roots much easier.
How to Dig Canna Rhizomes
The goal when digging is to lift the entire clump out of the earth without bruising or cutting the fleshy roots. Any wound on a rhizome is an invitation for fungus or rot to enter during the winter months.
Use the Right Tools
A garden fork is often better than a pointed shovel for this task. The tines of a fork can slide through the soil and lift the clump from underneath with less risk of slicing through the middle of a rhizome. If you only have a shovel, just be sure to give the plant a wide berth.
The Lifting Process
Start digging about 10 to 12 inches away from the base of the stems. Sink your tool deep into the soil and gently pry upward. Work your way around the entire plant in a circle, loosening the soil as you go. You want to feel the whole mass "heave" upward.
Once the soil is loose, reach down and lift the clump by the base of the stems. If the clump is very large and heavy, don't try to lift it all at once. You can use your shovel to gently divide the mass into smaller, more manageable sections while it is still in the ground.
Shaking Off the Soil
Once the clump is out of the ground, gently shake it to remove loose dirt. You can use your hands to brush away more soil, but avoid being too aggressive. The skin of a freshly dug canna rhizome can be surprisingly thin. If the soil is very sticky or clay-heavy, you can use a gentle stream of water from a garden hose to rinse them off. If you do use water, just remember that the rhizomes will need extra time to dry before they go into storage.
Key Takeaway: Treat canna rhizomes like eggs. Use a garden fork to lift them gently from a distance of 12 inches to prevent cuts and bruises that could lead to winter rot.
The Curing Process
One of the most common mistakes gardeners make is putting their "bulbs" directly into storage containers while they are still wet and cold. This leads to mold and decay. Instead, cannas need a short period of "curing."
Drying Out
Place your cleaned rhizomes in a dry, frost-free area for a few days. A garage, a shed, or even a covered porch works well. Spread them out in a single layer on a piece of cardboard or a newspaper. Do not stack them on top of each other.
This drying period—usually 2 to 4 days—allows the outer skin to toughen up slightly. It also ensures that any remaining bits of soil or moisture on the surface evaporate. If the weather is particularly humid, you might need to leave them for up to a week. They should feel dry to the touch and the cut ends of the stems should look "calloused" or dried over.
Inspecting for Health
While your cannas are drying, take a moment to look them over. Look for any soft spots, holes from pests, or signs of disease. If a rhizome feels mushy when you give it a gentle squeeze, it is best to discard it now. One rotting rhizome in a storage box can quickly spread its problems to the rest of the bunch.
Dividing for More Plants
One of the most exciting parts of growing cannas is how much they multiply. A single rhizome planted in May can often turn into a massive clump by October. Digging them up in the fall is the perfect time to divide them, giving you plenty of free plants to share with neighbors or to expand your own garden.
Where to Make the Cut
Look at the clump of rhizomes. You will see several "eyes" or growing points. These look like small, pointed bumps or tips on the surface of the root. For a division to grow into a successful plant next year, it needs to have at least one or two healthy eyes.
You can often pull the clumps apart with your hands, as they naturally want to separate at certain points. If they are too tough, use a clean, sharp knife to cut them. Each piece should be about the size of a large potato.
Labeling Your Varieties
If you grow different types of cannas—some with red flowers, some with yellow, or those with variegated leaves—be sure to label them now. Once they are dug and cleaned, all canna rhizomes look remarkably similar. You can write the variety name directly on the rhizome with a felt-tip marker, or place them in labeled paper bags. At Longfield Gardens, we always recommend labeling as you go to avoid any "mystery" gardens in the spring.
Packing and Storage Materials
The secret to successful winter storage is maintaining the perfect balance of moisture. You want the rhizomes to stay dormant and dry enough that they don't rot, but "plump" enough that they don't completely shrivel up and die.
Choosing a Packing Medium
Don't just throw the rhizomes into an empty plastic bin. They need to be nestled in a material that regulates moisture. Common choices include:
- Peat Moss: This is the gold standard. It holds a tiny bit of moisture but stays airy.
- Vermiculite or Perlite: These are lightweight and excellent for preventing rot.
- Wood Shavings or Sawdust: Make sure it is from untreated wood.
- Shredded Newspaper: A great, budget-friendly option.
- Dry Leaves: Nature’s own packing material.
The Storage Container
Use a container that allows for a small amount of airflow. Cardboard boxes, plastic bins with holes drilled in the sides, or even old milk crates lined with newspaper work well.
Place a layer of your chosen packing material in the bottom. Lay the rhizomes on top so they aren't touching each other. Cover them with more material and repeat the layers until the container is full. If you use a plastic bin with a lid, leave the lid slightly ajar or don't snap it down tight. This prevents condensation from building up inside.
Where to Keep Them All Winter
Once your cannas are packed, they need to go somewhere dark and cool. The ideal temperature range is between 40°F and 50°F.
The Ideal Spot
A cool basement, a crawl space, or a "fruit cellar" is perfect. In some regions, an attached garage that stays above freezing might work, but you have to be careful. If the temperature drops below 32°F in the garage, the rhizomes will die. Conversely, if the storage area is too warm (like a closet inside a heated house), the plants might think it is spring and start to grow prematurely, or they may simply dry out and shrivel.
Checking In
Don't just "set it and forget it." Mark your calendar to check on your stored cannas once a month. This only takes five minutes. Reach into the box and feel a few of the rhizomes.
- If they feel shriveled: Use a spray bottle to lightly mist the packing material with water. You don't want it wet, just barely damp.
- If they feel mushy or look moldy: Remove the affected pieces immediately and leave the lid off for a few days to increase airflow.
Key Takeaway: Storage is about balance. Keep them cool (40–50°F) and check them monthly to ensure they aren't drying out or rotting.
Handling Canna Lilies in Pots
If you grow your cannas in large decorative containers, you have a slightly easier path. You don't necessarily have to dig the rhizomes out of the soil.
The "Dormant Pot" Method
Once the frost has hit the foliage, cut the stems back just like you would for in-ground plants. Instead of digging, simply move the entire pot into a cool, dark, frost-free location like a basement or garage.
Stop watering the pot entirely. The soil will dry out, and the rhizomes will go dormant right where they are. In the spring, about six weeks before the last frost, you can bring the pot back into the light, give it a good soak, and watch the new growth emerge. Eventually, however, you will need to empty the pot and divide the rhizomes because cannas grow so fast they will eventually become "root-bound" and stop blooming well.
Bringing Cannas Back in Spring
While this guide focuses on the fall, it helps to know what you are working toward. In the spring, you should wait until the danger of frost has passed and the soil has warmed up to about 60°F before planting your stored rhizomes back outside.
If you live in a northern area with a short growing season, you can start your cannas indoors in pots about a month before the last frost. This gives them a head start so they are already several inches tall when they finally move to the garden.
What to do next:
- In late winter, check your storage boxes one last time for any rot.
- Prepare your garden beds with compost or well-rotted manure.
- Plan your layout, keeping in mind that cannas love full sun and plenty of water.
- When the ground is warm, plant them about 2 to 3 inches deep with the "eyes" facing up.
Common Myths About Digging Cannas
In the world of gardening, there are many "old wives' tales" that can make tasks seem more complicated than they really are. Let's clear up a few for cannas.
Myth: You must wash them with bleach. Some people suggest dipping rhizomes in a 10% bleach solution to prevent rot. While this can kill surface bacteria, it isn't usually necessary for the home gardener if the rhizomes are cured properly and stored in a breathable medium.
Myth: You have to dig them the very minute frost hits. While you shouldn't wait until the ground freezes, you don't need to panic. If the frost hits on a Tuesday and you can't get to the garden until Saturday, your cannas will be perfectly fine. The soil acts as an insulator for those few extra days.
Myth: Small pieces won't grow. Even a relatively small piece of a rhizome can grow into a full plant as long as it has at least one healthy "eye." Don't throw away the smaller chunks that break off during digging; plant them in a nursery corner and see what happens!
Troubleshooting Fall Problems
Even with the best timing, nature can throw a curveball. Here is how to handle a few common late-season scenarios.
Early Hard Freeze
If a surprise "Polar Vortex" or early hard freeze is predicted before you have had a chance to dig, don't worry. You can temporarily protect the rhizomes by piling a thick layer of mulch, straw, or even old blankets over the base of the plants. This should buy you a few extra days to get the digging done.
Wet Fall Weather
If the fall has been incredibly rainy, your rhizomes will be saturated with water. In this case, the curing process is even more critical. You may want to set up a small fan in your drying area to move air around the rhizomes and ensure they dry out thoroughly before being packed away.
Pests in the Roots
If you find holes or tunnels in your rhizomes while digging, you might have dealt with some overzealous garden grubs. Cut away the damaged portions with a clean knife. As long as most of the rhizome is firm and healthy, it should still store and grow just fine.
Conclusion
Digging up canna bulbs in the fall is a simple, rewarding task that preserves the beauty of your garden for years to come. By waiting for the first frost to signal dormancy, you allow the plant to store the energy it needs to thrive next season. Whether you are tucking them into a bed of peat moss in the basement or moving your favorite pots into a cool corner of the garage, the effort you put in now will be repaid with lush, tropical blooms all summer long.
We are proud to provide high-quality plants and the practical knowledge you need to succeed. Gardening shouldn't be a source of stress; it's an opportunity to work with nature and enjoy the results of your care. With a little attention to the weather and a gentle hand with the shovel, your cannas will be ready to dazzle you again next year.
"The secret to beautiful cannas isn't a special fertilizer or a secret trick; it's simply listening to the plant and the weather. When the frost arrives, it’s time to rest."
- Wait for the first frost to blacken the foliage before digging.
- Cure the rhizomes for a few days in a dry, frost-free spot.
- Store in a cool, dark place (40–50°F) in a breathable medium like peat moss.
- Check monthly to ensure they stay healthy and firm.
FAQ
Can I leave my cannas in the ground if I live in Zone 7?
In Zone 7, cannas can often survive the winter if the ground doesn't freeze too deeply and they are protected by a thick layer of mulch. However, if a severe winter occurs, they may rot or die. Many gardeners in this zone dig up their most valued varieties as insurance against a particularly cold year.
Do I need to wash the dirt off the rhizomes before storing them?
It is not strictly necessary to wash them, and sometimes shaking or brushing the soil off is better to avoid adding excess moisture. However, if your soil is heavy clay and sticks to the roots, a gentle rinse can help you inspect the rhizome for damage. Just ensure they are 100% dry before you pack them away.
What happens if I dig my cannas before the first frost?
If you dig them too early, the plant may not have finished storing its energy reserves for the winter. The rhizomes might be smaller and more prone to shriveling during storage. If you must dig early due to travel or scheduling, try to keep as much soil around the roots as possible to minimize the shock.
My stored cannas have started growing sprouts in February. What should I do?
This usually means your storage area is a bit too warm. If possible, move the container to a cooler spot (around 40°F) to slow them down. If the sprouts are already several inches long, you may need to pot them up in soil and keep them in a sunny window until it is warm enough to move them outside.
