Table of Contents
- Introduction
- The Short Answer: It Depends on Your Zone
- Why Canna Rhizomes Need Winter Protection
- When is the Right Time to Dig?
- A Step-by-Step Guide to Lifting Canna Rhizomes
- How to Clean and Cure Your Rhizomes
- Choosing the Best Storage Method
- Monitoring Your Cannas Through the Winter
- An Alternative: Overwintering Cannas in Containers
- What Happens if You Leave Them in the Ground?
- Preparing for Spring Replanting
- Conclusion
- FAQ
Introduction
There is nothing quite like the tropical transformation a canna lily brings to a summer garden. With their towering heights and vibrant, paddle-shaped leaves, these plants turn any backyard into a lush retreat. At Longfield Gardens, we enjoy seeing how these striking perennials provide structure and bold color from midsummer until the first frost. Their reliability makes them a favorite for both garden beds and large patio containers.
This guide is designed for home gardeners who want to know exactly how to handle their cannas as the growing season winds down. Whether you are a beginner or a seasoned gardener, understanding winter care is the key to enjoying these plants year after year. We will cover how your local climate dictates your next steps and provide clear instructions for protecting your plants.
The simple answer to whether you must dig up your cannas depends entirely on where you live and your specific winter weather.
The Short Answer: It Depends on Your Zone
The decision to dig up your canna rhizomes—often called "bulbs"—is based on the USDA Plant Hardiness Zone of your region. Canna lilies are tropical and subtropical plants by nature. They thrive in heat and humidity but have very little natural resistance to freezing temperatures.
In warmer climates, specifically USDA zones 8 through 11, canna lilies are usually fine to stay in the ground all year. In these areas, the soil does not freeze deep enough to damage the fleshy rhizomes. You can simply cut the foliage back after it turns brown and let the plants rest until spring. Adding a thick layer of mulch helps keep the soil temperature stable during occasional cold snaps.
In colder regions, which include USDA zones 3 through 7, the ground freezes hard during the winter months. Because canna rhizomes contain a high amount of water, they will freeze and rot if left in the soil. For gardeners in these zones, you have two choices: treat the plants as annuals and buy new ones each spring, or dig them up and store them indoors. Most gardeners find that lifting and storing them is a rewarding way to preserve their favorite varieties.
Why Canna Rhizomes Need Winter Protection
To understand why winter care is necessary, it helps to look at the structure of the plant. What we call a "bulb" is actually a rhizome. This is a thick, fleshy underground stem that stores energy and water for the plant. Because these rhizomes are so full of moisture, they are very sensitive to ice crystals forming inside their tissues.
When the ground freezes, the water inside the rhizome expands as it turns to ice. This ruptures the cell walls of the plant. Once the ground thaws, the damaged tissue quickly turns to mush and rots. By lifting the rhizomes and moving them to a frost-free environment, you are simply keeping that stored energy safe until the weather is warm enough for growth to begin again.
This dormancy period is a natural part of the plant’s life cycle. Even in warmer climates, cannas appreciate a period of rest during the shorter, cooler days of winter. Providing the right environment during this "sleep" ensures the plant has the strength to produce those massive leaves and bright blooms next summer.
When is the Right Time to Dig?
Timing is one of the most important factors in successful canna storage. You do not want to dig them up too early. The plants use the late summer and early fall to send as much energy as possible down into the rhizomes for the coming year.
The best signal to start the process is the first "blackening" frost. When a light frost hits your garden, the sensitive leaves of the canna will turn brown or black and begin to wilt. This indicates that the growing season is over and the plant is moving into dormancy. Do not worry about the plant being "ruined" by this frost; the rhizomes are protected by the soil and are perfectly safe at this stage.
If you live in an area where a hard freeze happens suddenly, keep an eye on your local weather forecast. You should aim to dig the rhizomes up after the foliage has died back but before the ground itself freezes solid. In most northern states, this typically happens between late September and early November.
Key Takeaway: The Frost Signal
- Wait for the first frost to turn the leaves brown or black.
- The plant uses the final weeks of autumn to store energy in the rhizome.
- Plan to dig after the foliage dies but before the soil freezes hard.
A Step-by-Step Guide to Lifting Canna Rhizomes
Lifting cannas is a straightforward process that only requires a few basic garden tools. You will need a sturdy garden fork or a shovel and a pair of clean bypass pruners. Using a garden fork is often better because it is less likely to slice through the rhizomes than a flat spade.
Start by cutting the stalks down. Use your pruners to cut the stems about 3 to 4 inches above the soil line. These short "handles" of stem make the rhizomes easier to grab and help you remember which side is up later. Once the tops are removed, you can clear away any mulch or debris from the base of the plant.
When you begin digging, give the plant plenty of space. Canna rhizomes can spread surprisingly far in a single season. Insert your fork into the soil about 12 inches away from the center of the clump. Gently pry upward, working your way around the entire plant to loosen the root ball. Once the soil is loose, lift the entire mass of rhizomes out of the ground.
How to Clean and Cure Your Rhizomes
Once the cannas are out of the ground, the goal is to prepare them for a long period of inactivity. Start by gently shaking the clump to remove large chunks of soil. You can use your hands to brush away loose dirt, but avoid being too aggressive. The "skin" of a canna rhizome is relatively thin, and you want to keep it intact to prevent disease.
It is usually best to avoid washing the rhizomes with a hose. Adding excess moisture right before storage can encourage mold or rot. If the soil is very wet and sticky, let the clumps sit in a shaded, dry area like a garage or shed for a few hours. This makes the soil easier to crumble away.
Curing is the next vital step. This is a short drying period that allows the outer layer of the rhizome to toughen up. Place your cleaned rhizomes in a single layer on a tray or a piece of cardboard. Keep them in a well-ventilated, frost-free area for two to three days. Do not leave them in direct sunlight, as this can cause them to dry out too much. After curing, the rhizomes should feel dry to the touch, and any remaining soil should be easy to flick away.
Choosing the Best Storage Method
The environment where you store your cannas will determine if they make it through to spring in good health. The ideal storage location is dark, dry, and cool, with temperatures staying consistently between 40°F and 50°F. Unheated basements, crawl spaces, or insulated garages are often the best spots.
To prevent the rhizomes from shriveling up completely, you should pack them in a medium that holds a tiny bit of moisture but stays airy. Popular choices include:
- Dry peat moss
- Vermiculite
- Coarse wood shavings (like those used for animal bedding)
- Perlite
Place a layer of your chosen material in the bottom of a cardboard box, plastic bin, or paper bag. Lay the rhizomes on top so they are not touching each other, then cover them with more of the material. If you use a plastic bin, do not snap the lid on tight. Leave it slightly ajar or poke holes in the sides to allow for air circulation. If moisture gets trapped inside with no airflow, the rhizomes will likely rot.
What To Do Next: Storage Setup
- Find a cool, dark spot that stays between 40°F and 50°F.
- Prepare a box with peat moss or wood shavings.
- Pack rhizomes loosely so they do not touch.
- Ensure the container has some ventilation.
Monitoring Your Cannas Through the Winter
Successful overwintering is not a "set it and forget it" task. It is a good idea to check on your stored cannas about once a month. This allows you to catch small issues before they become big problems. Open your boxes and look for any signs of trouble.
If you notice a rhizome that feels soft, mushy, or smells bad, it is beginning to rot. Remove it immediately and throw it away so the rot does not spread to the healthy plants. If you see a small amount of surface mold, you can often wipe it off and increase the ventilation in your storage area.
On the other hand, if the rhizomes look very shriveled or feel extremely lightweight, they may be drying out too much. In this case, use a spray bottle to lightly mist the storage medium (the peat moss or shavings) with water. You only want the material to be barely damp, not wet. This small amount of humidity is usually enough to keep the rhizomes plump until spring.
An Alternative: Overwintering Cannas in Containers
If you grow your cannas in pots, you have a significant advantage when it comes to winter care. You can skip the digging entirely. When the first frost hits and the foliage dies back, simply cut the stems down to about 2 inches above the soil level.
Move the entire container into a frost-free area like a basement or garage. You do not need to remove the rhizomes from the soil. The potting mix acts as a natural insulator and keeps the rhizomes at a stable temperature. Since the plant is dormant, it does not need light, but it does need to stay dry.
Stop watering the container once you move it indoors. The goal is for the soil to remain dry through the winter so the rhizomes do not rot. In early spring, about six weeks before the last frost, you can move the pot back into a sunny window or a greenhouse and begin watering again to "wake up" the plant. This head start often results in much earlier blooms compared to plants put directly into the garden soil.
What Happens if You Leave Them in the Ground?
Sometimes life gets busy, and you might wonder what happens if you simply leave your cannas in the garden. In zones 8 and warmer, the answer is usually "nothing bad." The plants will go dormant, and as long as the soil has good drainage, they will sprout again when the ground warms up in the spring. Drainage is key; "wet feet" in cold soil is the primary killer of cannas in the south.
In zones 7 and colder, leaving them in the ground is a gamble. In a very mild winter, a canna planted deep in a protected spot near a south-facing wall might survive. However, in a standard winter, the frost will eventually reach the rhizomes. Once they freeze, the plant is dead.
If you choose to leave them in the ground in a borderline zone (like Zone 7), you should provide extra protection. After cutting the stalks down, pile 6 to 12 inches of mulch, straw, or shredded leaves over the site. Cover this with a waterproof tarp to keep the winter rain from soaking the soil. While this isn't a guarantee, it can sometimes keep the soil just warm enough for the rhizomes to survive.
Preparing for Spring Replanting
As the days get longer and the threat of frost passes, it is time to think about bringing your cannas back into the garden. At Longfield Gardens, we recommend waiting until the soil has warmed to at least 60°F before planting rhizomes outdoors. This is usually around the same time you would plant tomatoes or peppers in your area.
Before planting, take the rhizomes out of storage and inspect them one last time. They should be firm and may even show small "eyes" or buds beginning to grow. This is also the perfect time to divide your cannas. If a rhizome has grown quite large, you can break or cut it into smaller pieces. Just make sure each piece has at least two or three healthy buds.
Plant the rhizomes about 4 inches deep with the "eyes" facing upward. If you can't tell which way is up, lay the rhizome on its side; the plant will figure it out. Space them about 1 to 2 feet apart, depending on the variety’s mature size. Give them a good drink of water to settle the soil, and soon you will see those familiar tropical shoots poking through the ground.
Conclusion
Canna lilies are some of the most rewarding plants you can grow, offering a high-impact look with relatively simple care. While the question of whether you have to dig them up depends on your local climate, the process of saving them is an easy win for any gardener. By following these steps, you can preserve your favorite varieties and enjoy a bigger, bolder garden every year.
- Check your USDA zone to see if your cannas are hardy in your area.
- Wait for the first frost before cutting back and digging rhizomes.
- Store them in a cool, dark place using a dry medium like peat moss.
- Monitor your plants monthly to ensure they stay healthy through the winter.
We take great pride in providing high-quality plants that help you create a beautiful outdoor space. If you are looking to add more tropical flair to your yard, we invite you to explore our selection of Tall Cannas, Medium Cannas, and Assorted Cannas at Longfield Gardens.
"Gardening is a cycle of seasons, and protecting your favorite plants over the winter is simply the bridge to next year's success."
FAQ
How do I know if my canna rhizomes are still good in the spring?
Healthy canna rhizomes should feel firm and heavy for their size, similar to a fresh ginger root. If they feel hollow, lightweight, or mushy, they have likely dried out too much or rotted. You should also look for small, firm "eyes" or buds, which are often pink or white, indicating the plant is ready to grow.
Can I store canna rhizomes in the refrigerator?
While the temperature of a refrigerator is generally within the safe range for cannas, it is often too humid and lacks the necessary air circulation. Additionally, some fruits release gases that can damage stored bulbs. It is much better to use a cool basement, crawl space, or an insulated garage where the temperature remains stable but the air is not as stagnant.
Do I need to treat the rhizomes with fungicide before storing them?
For most home gardeners, a fungicide is not strictly necessary if the rhizomes are cured properly and stored in a dry medium. However, if you have had issues with rot in the past, you can lightly dust the cut ends with sulfur powder or a general garden fungicide. The most important preventative measure is making sure the rhizomes are dry to the touch before they go into the box.
Why didn't my cannas bloom after I replanted them?
The most common reason for a lack of blooms is a lack of sunlight or nutrients. Cannas need at least six to eight hours of direct sun to produce flowers. They are also "heavy feeders," meaning they require rich soil and regular fertilizer. Ensure you are planting them in a sunny spot and adding compost or a balanced fertilizer to the soil in the spring.