Do You Have to Dig Up Canna Bulbs Every Year?

Table of Contents

1. Introduction
2. Understanding Canna Hardiness Zones
3. Why Do Cannas Need Protection?
4. When Is the Best Time to Dig?
5. How to Dig and Lift Canna Rhizomes
6. Cleaning and Curing Your Rhizomes
7. Dividing Cannas for More Blooms
8. Ideal Storage Conditions
9. Caring for Potted Cannas in Winter
10. Common Storage Mistakes to Avoid
11. Preparing for Spring Planting
12. The Reward of the Extra Effort
13. Conclusion
14. FAQ

Introduction

There is nothing quite like the tropical flair that cannas bring to a summer garden. Their oversized, paddle-shaped leaves and vibrant, orchid-like blooms make any backyard feel like a lush getaway. At Longfield Gardens, we love how these fast-growing plants transform a landscape in just one season, providing height and color when other plants might start to fade in the summer heat.

Because cannas are so vigorous and beautiful, many gardeners want to ensure they return year after year. The question of whether you need to dig them up is one of the most common topics we encounter as the seasons change. The answer isn't a simple yes or no, but rather a "where do you live?"

In this guide, we will look at how your local climate determines your winter garden tasks and provide a clear path for keeping your cannas healthy through the coldest months. Understanding your hardiness zone map is the key to deciding if your canna rhizomes can stay tucked in the soil or if they need a cozy spot indoors.

Understanding Canna Hardiness Zones

The primary factor in deciding if you have to dig up canna bulbs every year is your USDA plant hardiness zone. Cannas are tropical and subtropical plants, which means they thrive in heat but are very sensitive to freezing temperatures. In their native environments, they grow year-round without a dormant period. In the United States, we have to mimic those conditions or protect the "bulbs"—which are technically called rhizomes—from deep freezes.

Zones 8 to 11: The Stay-in-Ground Regions

If you live in USDA zones 8, 9, 10, or 11, you generally do not need to dig up your cannas. In these warmer climates, the ground rarely freezes deep enough to reach and damage the rhizomes. You can simply leave them in place. Once the foliage dies back after the first light frost, you can cut the stems down to about two or three inches above the soil line. Adding a layer of mulch, such as straw or shredded leaves, provides a little extra protection and helps keep the soil moisture consistent.

Zone 7: The Borderline Zone

Zone 7 is the "maybe" zone. In a mild winter, cannas in zone 7 often survive just fine with a thick layer of mulch (about 6 inches). However, a particularly harsh or wet winter can cause the rhizomes to rot or freeze. Many gardeners in this zone choose to dig up their most prized varieties just to be safe, while leaving others in the ground as a "test." If you have a sheltered spot near a south-facing wall, your cannas have a much higher chance of surviving the winter outdoors in zone 7.

Zones 3 to 6: The Must-Dig Regions

For those of us in zones 6 and colder, the ground freezes deep enough to turn a canna rhizome into mush. In these areas, you definitely have to dig up your cannas every year if you want to save them for the next season. While it might seem like a big task, it is actually a rewarding way to see how much your plants have grown. One single rhizome planted in the spring can often turn into a large clump by autumn, giving you even more plants for free the following year.

Key Takeaway: Check your USDA hardiness zone first. If you are in zone 6 or colder, digging is required. In zone 8 or warmer, you can relax and leave them in the ground.

Why Do Cannas Need Protection?

To understand why we dig, it helps to know what is happening underground. For a broader overview, see All About Cannas.

A canna rhizome is a fleshy, energy-storing stem that grows horizontally under the soil. It is packed with moisture and nutrients to fuel the plant’s rapid growth.

Because these rhizomes have high water content, they are very susceptible to ice crystals forming inside their cells. When the ground freezes, the water inside the rhizome expands, breaking the cell walls and causing the structure to collapse. Once the ground thaws, the damaged rhizome quickly turns into a soft, rotten mass.

Beyond the cold, winter moisture is a significant threat. Even in slightly warmer zones, if the soil stays cold and waterlogged for months, the dormant rhizomes can succumb to fungal rot. Digging them up allows you to control their environment, keeping them in a state of "suspended animation" where they stay dry and cool but not frozen.

When Is the Best Time to Dig?

Timing is everything when it comes to overwintering cannas. You want to give the plants as much time as possible to store energy, but you must move before the ground freezes solid.

The best signal is the first "killing frost." This is the frost that turns the lush green leaves to a dark brown or black and makes them look a bit wilted. This frost tells the plant that the growing season is over and it is time to go dormant.

Don't worry if you can't get to them the very next morning. The rhizomes are safe as long as the soil itself hasn't frozen. In fact, leaving them in the ground for a few days after the foliage dies can help the "eyes" (the growth points) on the rhizome become more visible, which is helpful if you plan on dividing them.

How to Dig and Lift Canna Rhizomes

When you are ready to dig, the goal is to lift the entire clump without slicing through the healthy rhizomes. Since cannas can multiply significantly over a single summer, the root mass might be much larger than you expect.

1. Cut back the foliage: Use garden shears to cut the stems down to about 4 inches above the ground. This gives you a "handle" to grab and makes the clump easier to manage.
2. Loosen the soil: Use a garden fork or a spade. Start digging about a foot away from the base of the stems. Digging too close can easily chop a rhizome in half.
3. Lift gently: Circle the plant with your shovel, prying upward from different angles. Once the soil is loose, lift the entire mass out of the ground.
4. Shake off excess soil: You don't need to get them perfectly clean yet, but removing the heavy clods of dirt makes them easier to carry to your workspace.

For a step-by-step walk-through, see our how to dig up and store canna lily bulbs guide.

What to do next:

• Label your plants immediately using a permanent marker on the stem or a tag.
• Move the clumps to a garage or shed where they are protected from rain.
• Check for any soft or mushy spots and discard those pieces immediately.

Cleaning and Curing Your Rhizomes

Once the cannas are out of the ground, they need a little bit of "spa time" before they go into storage. For more storage details, see Storing Canna Lily Bulbs Over Winter.

Some gardeners prefer to wash their rhizomes with a hose to remove all the soil. This makes it easier to spot pests or rot, but it also adds moisture. If you wash them, you must be extra diligent about the drying process. If you have sandy soil, you can often just let the soil dry and then brush it off with your hands.

To cure the rhizomes, spread them out in a single layer in a well-ventilated area that stays around 60–70°F. A garage, basement, or covered porch works well. Let them sit for two to three days. This allows the outer skin to toughen up slightly, which helps prevent them from drying out too much or rotting during the long winter months.

After curing, you can trim the remaining stems down to about an inch. You can also trim off the long, thin "whisker" roots. These roots won't be needed next year, and removing them makes storage much tidier.

Dividing Cannas for More Blooms

One of the most exciting parts of digging up cannas is seeing how they have multiplied. A single rhizome can often produce five or ten new growth points over the summer. Fall is a great time to divide them, though some gardeners prefer to wait until spring.

To divide them, look for the "eyes." These look like small, rounded bumps or points on the rhizome, similar to the eyes on a potato. Each division needs at least one healthy eye to grow a new plant next year, but two or three eyes per piece will give you a stronger, faster-growing plant.

You can usually snap the rhizomes apart by hand at the narrow points where they joined. If they are too tough, use a clean, sharp knife. If you use a knife, let the cut pieces sit for another day to "callus over" before putting them into storage. This prevents pathogens from entering the fresh wound.

Ideal Storage Conditions

The "Goldilocks" environment for canna storage is cool, dark, and slightly humid, but not wet. You want the temperature to stay between 40°F and 50°F. If it's too warm, the cannas might try to start growing in the dark. If it's too cold (below 35°F), they risk freezing.

Choice of Storage Medium

You shouldn't just throw the rhizomes in a plastic bin and close the lid. They need to breathe, and they need something to regulate moisture. Common choices include:

• Peat moss: Excellent for holding just the right amount of moisture.
• Vermiculite or Perlite: Very clean and effective.
• Wood shavings or sawdust: Good for airflow.
• Damp sand: A traditional method, though it makes the containers very heavy.
• Newspaper: Wrapping individual rhizomes in newspaper is a great, low-cost way to keep them separated so that if one rots, it doesn't spread to the others.

The Container

Plastic bins with air holes drilled in the sides, cardboard boxes, or even open milk crates work well. Layer your storage medium in the bottom, place the rhizomes so they aren't touching, and then cover them with more of the medium.

Key Takeaway: Think of storage as a nap, not a deep freeze. The rhizomes need to stay dormant and plump without getting wet enough to mold.

Caring for Potted Cannas in Winter

If you grow your cannas in large decorative pots, you have a bit of a "cheat code." You don't necessarily have to dig the rhizomes out of the soil. If you want a more compact display, browse Short Cannas.

Once the first frost hits, cut the foliage back as you would for garden-grown plants. Move the entire pot into a frost-free area like a basement or a crawlspace. You can leave the rhizomes right in the potting soil. The soil will act as the storage medium.

The most important rule for potted cannas is to stop watering them. They need to stay dry to remain dormant. In early spring, you can bring the pot back into the light, give it a good soak and some fresh fertilizer, and it will begin to sprout all over again. Eventually, the rhizomes will become so crowded in the pot that you will need to tip it out and divide them, but this usually only needs to be done every two or three years.

Common Storage Mistakes to Avoid

Gardening is a learning process, and overwintering cannas is no different. Most issues during the winter come down to moisture management.

The "Dry Out" Problem

If the storage area is too dry (like a heated basement), the rhizomes can shrivel up. If they look like prunes in mid-winter, they may have lost too much moisture to recover. To prevent this, you can lightly mist your storage medium (the peat moss or shavings) with a spray bottle once a month. You don't want it wet—just "not bone dry."

The "Rot" Problem

This is the opposite of the dry out problem. If the container has no airflow or the medium was too wet when you packed them away, the rhizomes will turn to mush. This is why we recommend checking your storage bins once a month. If you find a soft or moldy rhizome, remove it immediately so the rot doesn't spread to its neighbors.

The "Early Sprout" Problem

If your storage area gets too much light or the temperature stays above 55°F, your cannas might think spring has arrived in January. You'll see pale, white shoots reaching up. If this happens, try to move them to a cooler, darker spot to slow them down. Don't break the sprouts off; just try to keep them dormant until it's time to plant.

Preparing for Spring Planting

When the birds start singing and the soil begins to warm up, it’s time to wake up your cannas. This is usually about the same time you would plant tomatoes—once all danger of frost has passed and the soil temperature is at least 60°F.

If you want an earlier show of flowers, you can "start" your cannas indoors 4 to 6 weeks before the last frost. Plant the rhizomes in pots with potting soil and place them in a sunny window or under grow lights. For more planting-depth tips, see How Deep to Plant a Canna Bulb.

When planting, remember the simple rule for depth: plant the rhizomes about 4 inches deep. If you can see the eyes or sprouts, make sure they are pointing upward. Space them about 1 to 2 feet apart, as they will grow quite large by mid-summer.

The Reward of the Extra Effort

While digging up cannas every year in northern climates requires a bit of work, the reward is well worth it. For a mid-height option, browse Medium Cannas. There is a special satisfaction in seeing your collection grow from a few small pieces into a massive display of tropical color.

By taking the time to protect your cannas, you are ensuring that your garden remains a vibrant, high-impact landscape year after year. Whether you live in the sunny South where they stay in the ground, or the snowy North where they spend winter in the basement, cannas are one of the most reliable and spectacular plants you can grow. At Longfield Gardens, we take pride in providing high-quality rhizomes that are ready to perform, and with these simple storage steps, you can enjoy that performance for many seasons to come.

Final Checklist for Winter:

• Identify your zone to see if digging is necessary.
• Wait for the first frost to signal dormancy.
• Dig carefully, leaving at least a foot of space around the plant.
• Cure for 2-3 days before packing in a breathable medium.
• Store at 40-50°F and check monthly for rot or shriveling.

Conclusion

Whether you choose to leave your cannas in the ground or bring them inside for the winter depends entirely on your local environment. Gardening is most enjoyable when we work with nature rather than against it, and understanding the needs of these tropical beauties is the first step toward success. By following these simple steps for digging and storage, you can protect your investment and look forward to an even bigger, bolder garden next year.

• Know your zone to determine if your cannas can stay outside.
• Use the first frost as your guide for when to start the process.
• Keep storage conditions cool and dry to prevent rot.

If you are looking to expand your garden or try a new variety, we invite you to explore our canna collection of summer-blooming bulbs. We stand behind the quality of every rhizome we ship, and we are here to help you grow the garden of your dreams. For the best results, always plant your cannas in a sunny spot with plenty of water, and they will reward you with a summer full of spectacular color.

We help home gardeners create more beautiful spaces with premium plants and practical advice. If you ever have a question about your cannas or need help planning your next garden, our team at Longfield Gardens is always ready to support you. For order questions, contact us.

FAQ

What happens if I don't dig up my cannas in a cold zone?

In USDA zones 6 and colder, canna rhizomes will almost certainly freeze and die if left in the ground. The water inside the fleshy rhizome turns to ice, causing the structure to rot once it thaws. To enjoy them next year, you must lift them and store them in a frost-free area.

Can I store cannas in my garage?

You can store cannas in a garage as long as it stays above freezing. If your garage is uninsulated and temperatures drop below 32°F inside, the rhizomes will be damaged. A basement, crawlspace, or a cool closet inside the house is often a safer choice for consistent temperatures.

How do I know if my stored canna rhizomes are still good?

A healthy rhizome should feel firm and heavy for its size, similar to a fresh potato. If it feels very light and shriveled, it has dried out too much. If it feels soft, mushy, or has a sour smell, it has rotted and should be thrown away.

Should I wash the dirt off the cannas before storing them?

You can either wash them or simply brush off the dry soil. Washing makes it easier to see the eyes and any potential rot, but it requires you to be very careful about drying the rhizomes completely before they go into storage. If you have a lot of plants, brushing off the dry soil is often the faster and safer method.