Table of Contents
- Introduction
- Understanding Canna Rhizomes
- When to Begin the Process
- How to Dig and Lift Canna Rhizomes
- Cleaning and Preparing for Storage
- The Importance of Curing
- Choosing the Right Storage Medium
- Finding the Perfect Storage Location
- Winter Monitoring and Maintenance
- Storing Cannas Grown in Containers
- Preparing for Spring Planting
- Common Myths About Canna Storage
- Conclusion
- FAQ
Introduction
One of the greatest joys of a summer garden is the dramatic, tropical flair of cannas. These bold plants, with their paddle-shaped leaves and vibrant blooms, transform any backyard into a lush retreat. Whether you grow tall varieties with variegated foliage or compact types for containers, cannas are incredibly rewarding. Because we want you to enjoy these beautiful plants year after year, learning the simple process of winter storage is a great way to protect your investment.
At Longfield Gardens, we specialize in helping you find the highest quality plants to fill your landscape with color. While cannas thrive in the summer heat, they are tender perennials that cannot survive freezing ground temperatures in most parts of the country. Storing them indoors is an easy and effective way to ensure they come back even bigger and better next season.
This guide will walk you through the straightforward steps of lifting, curing, and storing your canna rhizomes. By following these practical tips, you can keep your favorite varieties safe until the warm weather returns. Saving your cannas is a satisfying end-of-season task that makes the arrival of spring even more exciting.
Understanding Canna Rhizomes
Before you start digging, it helps to understand what you are working with. Although most gardeners refer to them as "bulbs," cannas actually grow from canna rhizomes. A rhizome is a fleshy, underground stem that grows horizontally. It stores energy and nutrients for the plant, allowing it to produce those massive leaves and bright flowers every summer.
Over a single growing season, a small canna rhizome can expand significantly. By the time fall arrives, you will likely find that your single plant has turned into a large, heavy clump of several interconnected rhizomes. This natural growth is one of the best parts of gardening with cannas. When you store them correctly, you aren't just saving one plant; you are often gaining several new ones to plant in other parts of your yard or to share with friends.
The health of the rhizome determines the vigor of the plant next year. This is why we focus on careful handling during the storage process. A firm, plump rhizome is full of stored energy, ready to sprout as soon as the soil warms up in the spring.
When to Begin the Process
Timing is the most important factor when it comes to successfully overwintering your cannas. You want to give the plants as much time as possible to store energy, but you must move them indoors before a deep freeze reaches the roots.
In most regions, the signal to start is the first light frost. You will notice the lush green leaves turn black or brown almost overnight after a cold snap. This may look disappointing at first, but it is actually a helpful signal from nature. The frost tells the plant to stop growing and send all its remaining energy down into the rhizome for dormancy.
Monitoring Your Local Weather
Keep an eye on your local forecast as autumn progresses. A light surface frost that kills the foliage is fine, and even beneficial. However, you should aim to have your cannas out of the ground before a "hard freeze," which is when temperatures drop significantly below freezing for several hours. If the ground itself freezes solid, it can damage the cellular structure of the rhizome and lead to rot.
Key Takeaway: Wait for the first light frost to kill the foliage before digging. This ensures the plant has finished storing energy for the winter.
What to Do Next:
- Identify which canna varieties you want to save.
- Gather your tools, including a sturdy garden fork or shovel.
- Prepare a workspace in a garage, shed, or basement.
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 fleshy rhizomes. Damaged rhizomes are more prone to infection and rot during the winter months. Using the right technique makes this task much easier.
Step 1: Trim the Foliage
Start by cutting the stalks back. Use a pair of clean garden shears or a sharp knife to cut the stems about 2 to 4 inches above the soil line. Removing the bulky leaves and stalks first makes it much easier to see where the base of the plant is and gives you more room to work.
Step 2: Loosen the Soil
Instead of digging right next to the stem, move your shovel or garden fork about 6 to 10 inches away from the base of the plant. Cannas have wide-reaching root systems, and the rhizomes often grow outward. By starting your circle further out, you minimize the risk of accidental damage.
Step 3: Lift the Clump
Push your tool deep into the soil and gently pry upward. Work your way around the plant, loosening the earth on all sides. Once the soil is loose, you should be able to lift the entire clump out of the ground. Don't be surprised if the clump is quite heavy; a healthy canna can produce a substantial mass of rhizomes in a single season.
Cleaning and Preparing for Storage
Once the cannas are out of the ground, they need a bit of cleaning. You don't need to make them perfectly spotless, but removing excess soil helps prevent moisture from being trapped against the skin during storage.
Gently shake the clump to remove large chunks of dirt. You can use your hands to brush away more soil, but be careful not to skin or bruise the rhizomes. Some gardeners prefer to use a garden hose to wash the rhizomes clean. This is perfectly fine, but if you choose to rinse them, you must be extra diligent about the drying process that follows.
Should You Divide Them Now?
While you can divide canna clumps in the fall, we usually recommend waiting until the spring. Keeping the clumps larger over the winter helps prevent the individual rhizomes from drying out too much. In the spring, when you can see the "eyes" (the small bumps where new growth will emerge) more clearly, it is much easier to make successful divisions.
Key Takeaway: Handle the rhizomes gently to avoid bruising. A little bit of clinging soil is better than a damaged, scratched rhizome.
The Importance of Curing
Curing is perhaps the most overlooked step in storing canna bulbs, but it is essential for long-term success. Curing simply means letting the rhizomes air dry in a protected area for a few days. This process allows the outer skin to toughen up and any small nicks to "callous" over.
How to Cure Your Cannas
Place your cleaned rhizomes on a piece of cardboard, a wooden pallet, or a mesh screen in a well-ventilated area. A garage, garden shed, or even a covered porch works well, provided the temperatures stay above freezing.
Keep them out of direct sunlight and away from damp areas. Let them dry for about 3 to 7 days. If the weather is particularly humid, they might need the full week. You will know they are ready when the outer skin feels firm and any remaining soil is completely dry and crumbly.
What to Do Next:
- Spread the rhizomes out so they aren't touching each other during curing.
- Ensure the area has good airflow.
- Check for any soft spots or signs of pests before moving to the final storage step.
Choosing the Right Storage Medium
You cannot simply toss canna rhizomes into a plastic bin and expect them to thrive. They need a storage environment that balances two conflicting needs: they must stay dry enough to avoid rot, but moist enough that they don't shrivel up and die.
Using a packing medium is the best way to achieve this balance. Here are the most effective materials to use:
- Peat Moss: This is a classic choice. It is lightweight, holds a tiny bit of moisture, and has natural antifungal properties.
- Vermiculite or Perlite: These minerals are excellent for maintaining a consistent environment.
- Wood Shavings: Pine or cedar shavings (the kind used for pet bedding) provide great airflow and are very affordable.
- Newspaper: Wrapping individual rhizomes in several layers of dry newspaper is a simple, low-cost method that works surprisingly well.
Packing the Containers
Use breathable containers like cardboard boxes, paper bags, or plastic bins with holes drilled in the sides. Start with a layer of your chosen medium at the bottom, then place a layer of rhizomes on top. Make sure they aren't touching each other. If one starts to rot, you don't want it to spread to the others. Add another layer of medium and continue until the box is full.
Finding the Perfect Storage Location
The location where you keep your packed cannas will determine if they stay dormant or start to grow too early. The goal is a "Goldilocks" temperature—not too hot and not too cold.
The ideal temperature range is between 40°F and 55°F.
- Unheated Basements: These are often the most reliable spots for winter storage.
- Crawl Spaces: These stay cool and dark, which is perfect for dormancy.
- Attached Garages: If your garage is insulated and stays above freezing, it can work well. However, be careful with uninsulated garages in very cold climates, as the temperature can easily drop below freezing.
Avoid storing your cannas in a room with a furnace or water heater, as the air will be too warm and dry. Likewise, avoid any spot prone to flooding or high humidity, like a damp cellar floor.
Winter Monitoring and Maintenance
Once your cannas are tucked away, your work is mostly done, but it is a good idea to check on them once a month. This small effort can save your entire collection if conditions change.
What to Look For
Open your storage boxes and take a quick look. You are checking for two main things:
- Rot: If you see any fuzzy mold or feel soft, mushy spots, remove those rhizomes immediately. If only a small part is affected, you can sometimes cut away the rot and let the healthy part re-dry, but usually, it is safest to discard the damaged piece.
- Shriveling: If the rhizomes feel very light and look wrinkled like a raisin, they are getting too dry. Use a spray bottle to lightly mist the storage medium. You don't want it wet, just slightly damp to the touch. This provides enough humidity to stop the shriveling.
Key Takeaway: Monthly check-ins are the best way to prevent a small problem from ruining your entire batch of stored cannas.
Storing Cannas Grown in Containers
If you grow Short Cannas in pots, the process is even simpler. You don't necessarily have to dig them up at all. This is a great time-saver for busy gardeners.
Once the first frost hits and the foliage dies back, cut the stalks down to the soil level as you would with garden-planted cannas. Move the entire pot into a cool, frost-free location like a basement or garage. Stop watering the pot completely. The soil will dry out, and the rhizomes will go into a deep sleep right inside the container.
In the spring, you can simply bring the pot back outside, start watering again, and the cannas will begin to grow. Every two or three years, however, you will still need to dump the pot out and divide the rhizomes, as they will eventually become "root-bound" and run out of space to grow.
Preparing for Spring Planting
While this guide focuses on storage, it is helpful to know what the end goal looks like. Your cannas will stay dormant until the days get longer and the temperatures rise.
In late spring, once the danger of frost has passed and the soil has warmed to about 60°F, you can bring your rhizomes out of storage. This is the perfect time to divide large clumps. Look for the "eyes" on the rhizomes and use a sharp, clean knife to cut them into sections. Ensure each section has at least one or two healthy eyes.
If you want an earlier start, you can plant your stored rhizomes in pots indoors about 4 to 6 weeks before the last frost date. Place them in a sunny window, and they will be well on their way to being large, beautiful plants by the time they are ready to move into the garden.
Common Myths About Canna Storage
Because cannas are so popular, there is a lot of conflicting advice online. At Longfield Gardens, our 100% Quality Guarantee keeps things simple and focuses on what actually works.
"You must wash them with bleach."
Some advice suggests a diluted bleach soak to prevent rot. While this can kill surface bacteria, it isn't usually necessary for the home gardener. If you cure them properly and keep them at the right temperature, they will stay healthy on their own.
"They must be stored in plastic bags."
Plastic bags can trap too much moisture and lead to rapid rotting. Breathable containers like cardboard or paper are always a better choice for long-term storage.
"You can't store them if they've been hit by a hard freeze."
If the ground freezes solid, the rhizomes might be lost. However, if only the top inch of soil froze, your cannas are likely still fine. Dig them up and inspect them; if they are still firm, they are worth saving!
Conclusion
Storing cannas over the winter is a simple, rewarding task that ensures your garden remains a tropical paradise year after year. By waiting for the first frost, curing the rhizomes properly, and providing a cool, breathable home for the winter, you are setting the stage for a spectacular summer display. We at Longfield Gardens love seeing gardeners succeed with these vibrant plants, and we believe that with just a little bit of autumn care, anyone can enjoy cannas for many seasons to come.
- Wait for the first frost to signal dormancy.
- Dig carefully and cure the rhizomes for several days.
- Pack in a breathable medium like peat moss or wood shavings.
- Check monthly for moisture levels and health.
Successful winter storage is about balance—keeping the rhizomes cool but not frozen, and dry but not desiccated.
The next step is easy: simply mark your calendar for that first autumn frost and get your storage boxes ready. You’ll be glad you did when those beautiful canna sprouts emerge next spring!
FAQ
Do I really need to dig up my cannas if I live in a warm climate?
If you live in USDA hardiness zones 8 through 10, you can usually leave your cannas in the ground all winter. In these areas, the soil typically doesn't freeze deep enough to harm the rhizomes. However, adding a thick layer of mulch over the top of the cut-back plants provides extra insurance against an unusually cold snap.
Can I store cannas in a refrigerator?
While a refrigerator is cool and dark, it is generally not recommended for cannas. Refrigerators are designed to remove moisture, which can cause the rhizomes to shrivel up too quickly. Additionally, some fruits release gases that can interfere with the dormancy of the plants. A cool basement or crawl space is a much better environment.
What should I do if my stored rhizomes look moldy?
If you see a light dusting of white mold, it usually means the air is a bit too damp. You can gently wipe it off and move the box to a spot with better airflow. However, if the rhizome is soft, mushy, or smells bad, it has started to rot. Discard any rotted pieces immediately so the problem doesn't spread to your healthy plants.
Is it better to wash the dirt off or leave it on for storage?
Both methods can work, but most gardeners find that shaking off the loose soil is sufficient. Leaving a small amount of dry soil can actually help protect the rhizome from drying out too much. If you do choose to wash them with a hose, you must ensure they are 100% dry before you pack them away, as any trapped water will lead to rot.