Introduction
The vibrant leaves and bold, tropical flowers of canna lilies are a highlight for many home gardeners. These plants bring a lush, exotic feel to any yard, blooming reliably through the hottest summer days. Because they are tropical plants, they thrive in the warmth but need a little extra care once the seasons begin to change.
At Longfield Gardens, we want to help you enjoy these stunning perennials year after year. While they are incredibly hardy in the summer, they cannot survive freezing ground temperatures in many parts of the country. Learning how to manage winter storage for canna lily bulbs, which are technically called rhizomes, is a simple skill that pays off every spring.
This guide will show you exactly how to dig, clean, and store your cannas so they stay healthy through the cold months. We will cover the best timing for your region and the most reliable storage methods for a successful start next season. Mastering this process is the best way to preserve your favorite varieties and expand your garden for free.
Knowing Your Hardiness Zone
Before you reach for your shovel, it is helpful to know if you actually need to dig up your cannas. The necessity of winter storage depends almost entirely on your USDA hardiness zone. These zones are based on the average minimum winter temperature in your area.
In zones 8 through 11, canna lilies are generally considered hardy. This means the ground does not freeze deep enough to damage the rhizomes. If you live in these warm regions, you can usually leave your plants in the ground all year. A light layer of mulch can provide a little extra protection against an unusual cold snap, but for the most part, your plants will go dormant and reappear in the spring.
Gardeners in zone 7 are in a "transition" area. In mild winters, cannas may survive in the ground if they are planted in a protected spot or covered with six to eight inches of mulch. However, a particularly cold winter can still damage them. Many gardeners in zone 7 choose to dig up a few of their favorites just to be safe.
If you live in zone 6 or colder, winter storage for canna lily bulbs is a requirement. In these regions, the frost penetrates deep into the soil, which will turn the fleshy rhizomes into mush. Because we ship our bulbs from Lakewood, New Jersey, we are very familiar with the needs of gardeners in cooler climates who want to keep their tropical plants thriving.
Key Takeaway Check your USDA zone first. If you are in zone 6 or colder, you must dig up your cannas to keep them alive. In zone 7, it is optional but often safer to dig them up or mulch heavily.
The Importance of Timing
Timing is one of the most important factors when it comes to successful winter storage. You want to give the plant as much time as possible to store energy, but you must act before the ground freezes solid.
The ideal signal to start the process is the first "blackening" frost. When a light frost hits, the foliage of the canna lily will turn brown or black and begin to wilt. This looks like the plant is dying, but it is actually a natural part of its life cycle. This cold snap sends a signal to the rhizome that it is time to go dormant.
During the late summer and early fall, the plant is busy moving sugars and nutrients from the leaves down into the underground rhizome. This stored energy is what allows the plant to grow so vigorously the following spring. By waiting until after the first frost to dig them up, you ensure the rhizome is as "recharged" as possible.
If a hard freeze is predicted and you have not had a light frost yet, it is okay to go ahead and dig them. While nature’s signal is helpful, it is better to dig them early than to let the underground rhizomes freeze.
Step-by-Step Digging Instructions
Digging up cannas is a straightforward task that only takes a few minutes per plant. Because canna rhizomes grow outward and can multiply significantly during the summer, you may find that a single plant has turned into a large, heavy clump.
Cut Back the Foliage
Start by cutting the stems down. Use a sharp pair of garden shears or a lopper to cut the stalks about 3 to 4 inches above the soil line. Removing the bulky leaves makes it much easier to see the base of the plant and move the clump once it is out of the ground. These stalks also serve as a handy "handle" when you are lifting the clump.
Dig a Wide Circle
Canna rhizomes grow horizontally just under the soil surface. To avoid slicing through the fleshy roots, start your digging about 6 to 10 inches away from the base of the stems. Use a garden spade or a sturdy garden fork to loosen the soil all the way around the plant.
Lift Carefully
Once the soil is loose, gently pry the clump upward. If the clump is large, you might need to lift from several different angles. Try to keep the soil attached at first to protect the rhizomes from bruising. A bruised rhizome is more likely to rot in storage, so handle them with the same care you would use for a ripe piece of fruit.
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What to do next:
- Identify the clumps you want to save.
- Wait for the first frost to blacken the leaves.
- Cut the stalks down to 3-4 inches.
- Dig a wide circle to avoid damaging the roots.
- Lift the entire clump gently from the soil.
Cleaning and Preparing the Rhizomes
Once the clumps are out of the ground, they need a bit of preparation before they go into storage. You have a few options for cleaning, depending on your soil type and personal preference.
If you have loose, sandy soil, you can often just shake the clump to remove the excess dirt. In heavier clay soil, the dirt might stick to the rhizomes. Some gardeners prefer to use a garden hose to wash the soil away. This makes it easier to see the health of the rhizomes and identify where to divide them.
However, if you do wash them with water, it is vital that you allow them to dry completely afterward. Any excess moisture trapped in the crevices of the rhizomes can lead to mold or rot.
After cleaning, take a moment to inspect the rhizomes. Look for any parts that feel soft, mushy, or look diseased. Use a clean, sharp knife to trim away these sections. Healthy canna rhizomes should feel firm, similar to a fresh potato. You should also trim off any long, thin "feeder" roots that are hanging off the main fleshy rhizomes.
The Curing Process
Curing is a simple but essential step that many beginners skip. Curing is the process of letting the rhizomes air dry in a protected area before you pack them away for the winter. This allows the "skin" of the rhizome to toughen up and any cuts made during digging to callus over.
Place your cleaned rhizomes in a single layer on a tray, a piece of cardboard, or a screen. Keep them in a dry, well-ventilated area that stays between 60°F and 70°F. A garage, shed, or covered porch works well, as long as they are protected from rain and freezing temperatures.
Let the cannas cure for about 3 to 7 days. You will notice the exterior becoming slightly drier and the cut ends looking firm and sealed. This dry barrier is the plant's first line of defense against rot during the long winter months. For more detail, see this guide to storing canna lily bulbs in winter.
Key Takeaway Never put freshly dug, wet rhizomes straight into a sealed container. The curing process is the most effective way to prevent rot and ensure your plants stay healthy until spring.
Dividing Canna Rhizomes
One of the best things about cannas is how much they multiply. A single rhizome planted in May can easily turn into a massive clump by October. Winter storage is the perfect time to divide these clumps. For additional guidance, read how to divide canna lily bulbs.
When to Divide
You can divide your cannas either in the fall during the storage process or in the spring before planting. Dividing in the fall saves space in your storage containers. Dividing in the spring allows you to see exactly where the "eyes" (growth points) are located as the plant begins to wake up.
How to Divide
Look for the "eyes" on the rhizome. These look like small, pointed bumps or buds, similar to the eyes on a potato. To ensure a healthy new plant, each division should have at least two or three of these eyes and a decent piece of the fleshy root attached.
You can often snap the rhizomes apart by hand at the narrow points where they naturally join. If they are too tough, use a clean, sharp knife. If you make new cuts while dividing, give the rhizomes an extra day or two of curing time to let those new wounds callus over.
Choosing the Right Storage Medium
Canna lilies are a bit like "Goldilocks" when it comes to moisture during storage. If they stay too wet, they rot. If they get too dry, they shrivel up and die. Using a storage medium helps regulate this moisture level.
At Longfield Gardens, we have found that several different materials work well for this purpose. You can choose the one that is most convenient for you:
Peat Moss or Vermiculite
Peat moss is a classic choice because it holds a tiny bit of moisture but stays loose enough to allow for airflow. Vermiculite or perlite also works well for the same reason. Simply fill a container halfway with the material, nestle the rhizomes inside so they aren't touching each other, and cover them with more peat moss.
Wood Shavings
Clean wood shavings, such as those sold for animal bedding, are excellent for winter storage. They are very dry and provide great insulation. They are also less messy than peat moss when it comes time to unpack the plants in the spring.
Newspaper
For a low-cost option, you can wrap each individual rhizome in a few sheets of dry newspaper. The paper acts as a buffer, preventing any rot from spreading from one root to another. Once wrapped, you can stack the rhizomes in a cardboard box or a plastic crate.
Plastic Bags with Holes
If you use plastic bags, make sure to poke several large holes in the sides for ventilation. A sealed plastic bag will trap moisture and cause the rhizomes to rot within weeks. Most gardeners prefer to use breathable containers like cardboard boxes or wooden crates.
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What to do next:
- Choose a storage medium like peat moss, shavings, or newspaper.
- Find a breathable container (cardboard box or crate).
- Place rhizomes in the container, ensuring they do not touch.
- Cover or wrap them to maintain a stable environment.
The Ideal Storage Environment
Once your cannas are packed, you need to find the right spot to keep them until spring. The goal is to keep them dormant but alive.
The ideal temperature for storing canna lily bulbs is between 45°F and 55°F. If the temperature stays much higher than 60°F, the plants may try to start growing in the dark, which wastes their energy. If the temperature drops below freezing, the rhizomes will be destroyed.
Common Storage Locations
- Unheated Basements: This is often the most reliable spot in many homes. It usually stays cool and relatively dark.
- Crawl Spaces: If your crawl space is accessible and stays above freezing, it provides the perfect cool, damp environment.
- Root Cellars: These are designed for exactly this kind of storage.
- Cool Closets: In a well-insulated home, an interior closet far away from heating vents might stay cool enough.
Avoid storing your cannas in an attic, as these spaces can get surprisingly hot on sunny winter days or dangerously cold at night. Attached garages can work, but you must be careful that the container is not sitting directly on a cold concrete floor, which can pull heat away and lead to freezing.
Monitoring Your Plants Through Winter
Winter storage is not a "set it and forget it" task. You should check on your rhizomes about once a month to make sure everything is going well. This small effort can save your entire collection if a problem starts to develop.
When you check your cannas, look for two main things: rot and dehydration.
Managing Rot
If you see a rhizome that has become soft, mushy, or has visible mold growing on it, remove it immediately. Rot can spread quickly through a storage container. By removing the affected piece early, you protect the rest of the batch. If the rot is only on a small tip, you can sometimes cut it off and let the healthy part dry out before putting it back.
Managing Dehydration
If the rhizomes look very shriveled and feel lightweight, they might be getting too dry. In this case, use a spray bottle to lightly mist the storage medium (the peat moss or shavings) with a little water. You do not want the medium to be wet—just slightly damp to the touch. This provides enough humidity to keep the rhizome from drying out completely.
Key Takeaway A quick monthly check is your best defense. Look for firm, healthy roots and adjust the moisture levels only if the rhizomes appear significantly shriveled.
Waking Up Cannas in the Spring
As the days get longer and the weather warms up, it will be time to pull your cannas out of storage. You can usually start this process about 4 to 6 weeks before your last expected spring frost date.
Many gardeners like to give their cannas a head start by "waking them up" indoors. To do this, take the rhizomes out of their storage containers and plant them in pots with regular potting soil. Place the pots in a warm, sunny window or under grow lights. For more information, see this guide to planting canna lily bulbs in pots.
By the time the danger of frost has passed in your area, you will have established plants with several inches of green growth. This can lead to flowers much earlier in the summer compared to planting dormant rhizomes directly into the ground.
When you are ready to move them outside, remember the "right plant, right place" rule. Cannas love full sun and rich, moist soil. If your soil is sandy, adding some compost can help hold the moisture these thirsty plants crave.
Storing Cannas in Containers
If you grow your canna lilies in large pots or containers, you have a shortcut available. You don't necessarily have to dig the rhizomes out of the soil.
Once the frost hits and you have cut back the foliage, you can simply move the entire container into a cool, frost-free area like a basement or garage. Stop watering the pot completely. The soil will dry out, and the plant will go dormant right in the container.
In the spring, you can bring the pot back into the light, give it a good soak with water, and the plants will usually begin to grow again. Every two or three years, however, you will still need to dump out the pot and divide the rhizomes, as they will eventually become "root-bound" and run out of space to grow. You can also review this guide to growing canna lilies in pots.
Frequently Asked Questions
Do I have to wait for a frost before digging up canna lilies?
It is highly recommended to wait for a light frost, as this tells the plant to move its energy into the rhizomes for winter. However, if your schedule or the weather forecast requires you to dig them earlier, you can do so. Just make sure the plants have had a full growing season to mature.
Can I store canna lily bulbs in the refrigerator?
While a refrigerator stays at a safe temperature, it is usually too dry for long-term storage of fleshy rhizomes. Additionally, some fruits in the fridge release ethylene gas, which can interfere with the plant’s dormancy. A cool basement or crawl space is a much better environment.
What should I do if my stored cannas start growing in February?
If you see white sprouts beginning to grow, your storage area is likely a bit too warm. You can try to find a cooler spot for them. If the sprouts are small, you can leave them; just be careful not to break them when you eventually plant. If they grow very long, you may need to pot them up and treat them as houseplants until spring.
My rhizomes feel very hard and dry—are they dead?
Canna rhizomes should feel firm, but if they are as hard as a rock and look extremely shriveled, they may have dried out too much. Try soaking them in a bucket of room-temperature water for 12 to 24 hours. If they plump up, they may still be viable. If they remain shriveled and light, they likely did not survive the winter.
Conclusion
Taking the time to manage winter storage for canna lily bulbs is one of the most rewarding tasks in the garden. It transforms a one-season plant into a long-term investment that grows more beautiful and impressive each year. By following these simple steps—timing your harvest with the frost, curing the rhizomes properly, and keeping them in a cool, dark place—you can ensure your garden is filled with tropical color every summer.
- Wait for the first frost to signal dormancy.
- Cure the rhizomes for several days before packing.
- Store in a breathable medium like peat moss or newspaper.
- Maintain a temperature between 45°F and 55°F.
At Longfield Gardens, we are proud to provide high-quality plants that bring joy to your landscape. With just a little bit of care during the winter months, your cannas will be ready to put on a spectacular show year after year.
"Winter storage is not just about protection; it is the bridge that connects one successful growing season to the next, allowing your garden to grow in both size and beauty."
