Table of Contents
- Introduction
- Understanding Your Canna Lilies
- When to Dig Up Your Canna Rhizomes
- Step-by-Step: Digging and Cleaning
- The Importance of Curing
- Dividing for More Plants
- Choosing Your Storage Method
- Finding the Ideal Storage Location
- Winter Maintenance and Monitoring
- Overwintering in Zones 7 and 8
- Waking Them Up in Spring
- Common Myths and Realities
- Troubleshooting Common Issues
- Enjoying the Rewards
- Conclusion
- FAQ
Introduction
If you love the bold, tropical look of canna lilies, you are not alone. These sun-loving plants are garden favorites for their vibrant flowers and lush, oversized foliage. While they thrive in the heat of summer, gardeners in cooler climates need a plan for the winter months. At Longfield Gardens, we want to help you enjoy these stunning plants year after year without the need to start from scratch every spring. Our canna care guide has more seasonal tips.
Overwintering canna lily bulbs—which are technically called rhizomes—is a straightforward and rewarding process. By following a few simple steps to harvest and store your plants, you can ensure they return with even more vigor next season. This guide is for any gardener who wants to save their favorite varieties and enjoy a bigger, more beautiful display every summer. Learning to protect your cannas is one of the most satisfying "easy wins" in the garden.
Understanding Your Canna Lilies
Canna lilies are tropical plants native to warm regions of the Americas. Because they evolved in places where the ground never freezes, they have not developed a natural way to survive cold winters. In the United States, cannas are considered perennials in USDA hardiness zones 8 through 10. In these areas, the soil stays warm enough that the rhizomes can remain in the ground year-round.
For those of us living in zone 7 or colder, the winter air and freezing soil are too much for these tropical beauties. When the temperature drops significantly, the water inside the fleshy rhizomes can freeze, causing the plant tissues to break down and rot. This is why we treat them as "tender perennials." We enjoy them in the garden all summer, then move them to a protected, frost-free spot for their winter nap.
The part of the plant we store is the rhizome. A rhizome is a thick, fleshy underground stem that stores energy for the plant. Think of it like a battery. During the summer, the leaves soak up sunlight and turn it into energy, which is then sent down to the rhizome. By the end of the season, the rhizome is packed with everything the plant needs to sprout again in the spring.
When to Dig Up Your Canna Rhizomes
Timing is everything when it comes to overwintering. You want to give your cannas as much time as possible to store energy, but you must get them out of the ground before a hard freeze sets in. A "hard freeze" is when the air temperature stays below 28°F for several hours, causing the ground itself to begin freezing. For a broader overview, see Winter Storage for Tender Bulbs and Tubers.
The best signal to start the process is the first light frost. You will know it has happened when the tops of your canna leaves turn black or dark brown. This might look a bit sad at first, but it is actually a helpful message from nature. The frost tells the plant that the growing season is over and it is time to go dormant.
Once the foliage has been nipped by frost, you generally have a window of a few days to a week to get them out of the soil. If you live in an area where the transition from autumn to deep winter happens quickly, keep a close eye on your local weather forecast.
Key Takeaway: Wait for the first light frost to turn the leaves brown before digging. This ensures the plant has finished storing energy for the winter.
What to do next:
- Monitor your local frost dates in the fall.
- Gather your tools (a garden fork or spade) once the leaves change color.
- Clear a space in a garage, basement, or shed for the curing process.
Step-by-Step: Digging and Cleaning
When you are ready to dig, the goal is to be as gentle as possible. Canna rhizomes can be quite large and heavy by the end of the summer, often growing much bigger than the original bulb you planted in the spring. If you want a mid-sized option for your next planting, browse our medium cannas.
Lifting the Rhizomes
Use a garden fork or a sturdy spade for this job. Start by cutting the stalks down to about 4 to 6 inches above the soil line. These short stems act as helpful handles while you work.
Insert your tool into the soil about a foot away from the center of the plant. You want to avoid accidentally slicing through the rhizomes. Gently pry upward, working your way around the entire clump until the root mass feels loose. Lift the entire clump out of the ground. Don't worry if the clump is large and heavy; this is a sign of a healthy, productive plant.
Initial Cleaning
Once the clump is out of the ground, shake it gently to remove large chunks of soil. You can use your hands to brush away more dirt, but avoid being too aggressive. The "skin" of a freshly dug rhizome is quite tender and can bruise or tear easily.
Some gardeners prefer to rinse their rhizomes with a garden hose to get them completely clean. This is fine, but if you do wash them, you must be extra diligent during the drying stage. Any excess moisture trapped in the nooks and crannies can lead to rot during storage.
Trimming the Foliage
After lifting, you can trim the stems back even further. Aim for about 2 to 3 inches of stem remaining above the rhizome. This is also a great time to trim away the long, thin "feeder" roots hanging off the main fleshy rhizomes. Trimming these makes the plants much easier to pack and store.
The Importance of Curing
Curing is perhaps the most overlooked step in the overwintering process, but it is one of the most important for success. Curing is simply a fancy word for letting the rhizomes air-dry for a short period. This process allows the outer skin to toughen up and any small nicks or cuts to "callus" over. A callused rhizome is much more resistant to mold and rot.
To cure your cannas, find a dry, well-ventilated spot that is protected from frost. A garage, a covered porch, or a garden shed works perfectly. Spread the rhizomes out in a single layer on a sheet of cardboard or several layers of newspaper.
Let them sit for about 7 to 10 days. During this time, you may see the remaining soil turn into a dry dust that is easy to brush off. The rhizomes will start to look a bit shriveled on the outside, which is perfectly normal. Avoid leaving them in direct sunlight, as this can dry them out too quickly and damage the internal tissues.
Key Takeaway: Curing for 7 to 10 days in a dry, shaded area creates a protective "skin" that prevents rot during the long winter months.
Dividing for More Plants
One of the best things about canna lilies is that they are very generous. Over a single summer, one rhizome can grow into a large clump with several "eyes." An eye is a small, pointed bump on the rhizome where new growth will emerge next year.
You can divide your cannas either in the fall after curing or in the spring before planting. Most gardeners find it easier to do in the fall when the plants are already out of the ground. If you're after a taller display, take a look at our tall cannas.
To divide, look for natural weak points in the clump. You can often snap the rhizomes apart with your hands, or use a clean, sharp knife for larger sections. Make sure each piece you keep has at least two or three healthy-looking eyes. If you use a knife, let the cut pieces cure for an extra day or two to ensure the fresh wounds are dry before they go into storage.
Choosing Your Storage Method
There is no "one right way" to store cannas, as the best method often depends on the space you have available. If you are working with a smaller space, our short cannas are worth a look. However, all successful methods share two goals: keeping the rhizomes cool enough to stay dormant and keeping them dry enough to prevent rot, but not so dry that they turn into "mummies."
The Box and Peat Moss Method
This is the most common and reliable method. Find a sturdy cardboard box or a plastic bin (if using plastic, do not put the lid on tight—airflow is vital).
- Place a 2-inch layer of dry peat moss, vermiculite, or wood shavings at the bottom.
- Lay your rhizomes on top, making sure they aren't touching each other.
- Cover them with another layer of your storage medium.
- You can stack multiple layers this way, ending with a layer of peat moss on top.
The peat moss or wood shavings act as an insulator and help regulate moisture. If one rhizome starts to rot, the dry material helps prevent the problem from spreading to its neighbors.
The Paper Bag Method
If you only have a few cannas, you can wrap each rhizome individually in a few sheets of newspaper and tuck them into a paper grocery bag. Store the bags in a cool spot. The paper allows the plants to "breathe" while providing enough protection to keep them from drying out completely.
The Pot Storage Method
If you grow your cannas in large containers, you can often leave them right in the pots. Once the frost hits, cut the foliage down to the soil level and move the entire pot to a cool, dark place like a basement or an attached garage. Do not water the pots at all during the winter. In the spring, you can pull the rhizomes out, divide them, and replant them with fresh soil. For a ready-made mix, see our assorted cannas.
Finding the Ideal Storage Location
The environment where you keep your cannas over the winter is just as important as how you pack them. We want to aim for what gardeners call "cold and dark."
The ideal temperature range is between 40°F and 50°F.
- If it's too warm: The rhizomes might think it is spring and start to sprout prematurely. This uses up their stored energy too early.
- If it's too cold: If the temperature drops below freezing (32°F), the rhizomes will likely be damaged or killed.
Good locations include:
- An unheated basement or crawlspace.
- A root cellar.
- A cool closet in a mudroom.
- An attached garage (as long as it stays above freezing).
Winter Maintenance and Monitoring
Overwintering isn't a "set it and forget it" task. It is a good idea to check on your stored rhizomes about once a month. This small effort can save your entire collection if a problem starts.
When you check them, look for two things: rot and desiccation (extreme drying).
Handling Rot
If you find a rhizome that feels soft, mushy, or has a foul smell, remove it immediately. If the rot is only on one small tip, you can sometimes cut that part off with a clean knife and let the healthy part dry out. However, if the whole piece is soft, it is best to throw it away so it doesn't infect the rest of your stock.
Handling Dryness
If the rhizomes feel very light and look extremely shriveled—like a piece of dry ginger—they may be getting too dry. In this case, you can lightly mist the storage medium (the peat moss or shavings) with a spray bottle. You aren't trying to make it wet; you just want to add a tiny hint of humidity back into the box.
What to do next:
- Set a monthly reminder on your phone to check your bulbs.
- Keep a spray bottle nearby for quick moisture adjustments.
- Always wash your hands or tools after handling a rotten rhizome to prevent spreading bacteria.
Overwintering in Zones 7 and 8
If you live in a region where the ground only freezes lightly and briefly, you might be able to leave your canna lilies in the ground. This is much less work, but it does carry a small amount of risk if an unusually cold winter arrives.
In Zone 7, "microclimates" are your best friend. Cannas planted against a south-facing brick wall, for example, will stay much warmer than those in the middle of an open yard. To help them survive outdoors:
- Wait for the frost to kill the foliage.
- Cut the stems down to the ground.
- Apply a thick layer of mulch. Use 6 to 10 inches of straw, shredded leaves, or wood chips. This act of "blanketing" the soil keeps the temperature stable and prevents the frost from reaching the rhizomes.
- In the spring, pull the mulch back once the soil begins to warm so the new shoots can emerge.
We generally recommend digging them up if you have a special variety you absolutely cannot afford to lose, as even Zone 7 can experience a "once-in-a-decade" deep freeze. If you are shopping ahead for next season, our spring-planted summer-blooming bulbs page is a good starting point.
Waking Them Up in Spring
When the days start to get longer and the birds return, it is time to think about replanting. You don't want to rush your cannas back into the garden too early. They are heat lovers and won't do much until the soil is warm.
A good rule of thumb is to wait until the danger of frost has passed and the soil temperature is consistently 60°F or higher. For a step-by-step refresher, our how to overwinter canna lily bulbs guide walks through the whole process.
Starting Early Indoors
If you want to get a head start on the season, you can "wake up" your cannas indoors about 4 to 6 weeks before the last frost.
- Take the rhizomes out of storage and inspect them one last time.
- Place them in pots with lightly moistened potting soil.
- Set the pots in a warm, sunny window or under grow lights.
- Once they have sprouted and the outdoor weather is warm, you can move the established plants into the garden. This method often results in earlier blooms.
Key Takeaway: Only move cannas back outside when the soil is warm and the threat of frost is gone. They love the sun, so choose the brightest spot in your garden.
Common Myths and Realities
When you search for advice on overwintering canna lily bulbs, you might come across some "internet hacks" that sound easier than the standard method. At Longfield Gardens, we prefer to stick to the basics because they are proven to work. If you have questions about when orders ship, our shipping information page explains the details.
One common myth is that you can store cannas in a bucket of water. This is a recipe for disaster. While cannas love water during the growing season, they need to be dormant in the winter. Keeping them in water will lead to rot within weeks.
Another myth is that you must use a bleach solution to "sanitize" the bulbs before storage. While this isn't necessarily harmful if done correctly, it is usually an unnecessary step for the home gardener. As long as you cure the rhizomes properly and store them in a dry medium, they have their own natural defenses against most soil-borne issues.
Finally, don't worry if you lose a few rhizomes over the winter. Even professional growers expect a small percentage of loss. If 80% of your cannas survive and sprout in the spring, you have done an excellent job!
Troubleshooting Common Issues
If you find that your cannas didn't make it through the winter, don't be discouraged. Most issues are easy to fix for the next season. Our 100% guarantee explains how we stand behind our plants.
Problem: Rhizomes turned to "mush."
- Cause: Too much moisture or a storage spot that was too warm.
- Solution: Ensure you cure them for a full week next time and use a breathable container like cardboard instead of a sealed plastic bin.
Problem: Rhizomes are "rock hard" and won't sprout.
- Cause: They dried out too much (desiccation).
- Solution: Check them monthly and add a tiny bit of moisture to the packing material if they feel light and brittle.
Problem: Early sprouting in February or March.
- Cause: The storage area is too warm.
- Solution: Move the box to a cooler spot, like a different corner of the basement or a lower shelf where the air is colder.
Enjoying the Rewards
The effort you put into overwintering canna lily bulbs pays off tenfold when summer arrives. Not only do you save money, but you also get the satisfaction of watching your garden grow and expand year after year. Those small rhizomes you tucked away in the fall will reward you with towering stalks of lush green or bronze foliage and brilliant flowers that hummers and butterflies love.
Gardening is a journey of learning what works best in your specific backyard. Every year you overwinter your cannas, you will get a better feel for the rhythm of your local climate. It is a rewarding cycle that connects you to the seasons and makes the first sprout of spring feel like a true celebration.
Conclusion
Overwintering canna lily bulbs is a simple, effective way to keep the tropical magic in your garden year after year. By waiting for the first frost, curing the rhizomes properly, and providing a cool, dry winter home, you are setting yourself up for success. We at Longfield Gardens believe that every gardener can master this process with just a little bit of patience and care.
- Wait for a light frost to trigger dormancy before digging.
- Cure the rhizomes for 7–10 days to toughen the skin.
- Store in a cool, dark place (40-50°F) using a breathable medium like peat moss.
- Check monthly for rot or extreme dryness.
Protecting your favorite plants over the winter is one of the most rewarding ways to grow your garden and your skills at the same time.
Ready to add more color to your landscape? We invite you to explore our selection of premium bulbs and perennials at Longfield Gardens to find the perfect companions for your cannas next season.
FAQ
Can I store canna lilies in my refrigerator?
While a refrigerator is cool and dark, it is usually not the best place for canna rhizomes. The humidity levels in a fridge can vary, and if you store fruits like apples nearby, they release ethylene gas which can damage the bulbs. A cool basement or garage is almost always a better choice. If you want more general help, see our FAQs.
Do I have to wash the dirt off before storing?
It is not strictly necessary to wash them, and sometimes it is actually safer to just brush the dry soil off. If you do wash them, you must be very careful to let them dry completely during the curing phase, as any trapped water can quickly lead to rot in storage. For the full process, see how to dig up and store canna lily bulbs.
How do I know if a rhizome is dead in the spring?
A healthy rhizome should feel firm, similar to a potato. If it is soft, squishy, or crumbles like dust when you squeeze it, it is likely no longer viable. If you see a small, firm "eye" or bud, even if the rest of the rhizome looks a bit shriveled, it is worth planting! If you want a refresher on timing and care, see our canna planting & care resources.
Can cannas be toxic to pets?
Canna lilies are generally considered non-toxic to dogs and cats by the ASPCA. However, any plant material can cause mild stomach upset if ingested in large quantities. It is always a good practice to store your bulbs and rhizomes out of reach of curious pets and children to avoid any choking hazards.