Introduction
There is nothing quite like the tropical transformation that canna lilies bring to a summer garden. With their lush, oversized foliage and vibrant, sunset-colored blooms, these plants make any backyard feel like a private getaway. At Longfield Gardens, we love how cannas bridge the gap between late summer and the first hints of autumn with their tireless energy. They are high-impact plants that offer a lot of reward for very little effort during the growing season.
As the days grow shorter and the air turns crisp, many gardeners start to wonder if these tropical beauties can handle the coming cold. Because cannas are native to much warmer climates, they have specific needs when it comes to surviving the winter months. Whether they stay in the ground or move into a cozy garage depends entirely on where you live and how you prepare them for their period of rest.
This guide will help you determine the best winter plan for your cannas based on your local hardiness zone. We will cover how to identify your hardiness zone, the steps for safely digging up rhizomes, and the best ways to store them so they are ready to shine again next spring. Our goal is to help you keep your canna collection growing and thriving year after year.
Whether you are a new gardener or a seasoned pro, protecting your cannas from the cold is a straightforward process that ensures your garden stays beautiful for seasons to come.
Understanding Your USDA Hardiness Zone
The most important factor in deciding if your canna bulbs will survive winter is your USDA hardiness zone. These zones are based on the average minimum winter temperature in your area. Because cannas are tropical plants, they do not have a natural "antifreeze" to protect their fleshy roots from solid ice.
In warmer regions, specifically USDA zones 8 through 11, cannas are usually considered perennial. This means you can leave them in the ground year-round. The soil in these areas rarely freezes deep enough to reach the rhizomes. With a little bit of extra mulch for insulation, these plants will simply go dormant and return when the soil warms up in the spring.
Gardeners in zone 7 live in a "swing" area. In many years, cannas can survive outside in zone 7 if they are planted in a protected spot, such as near a south-facing wall. However, an unusually cold winter can still pose a risk. Many gardeners in this zone choose to dig up their most prized varieties just to be safe, or they apply a very thick layer of mulch to keep the frost away.
If you live in zones 3 through 6, canna rhizomes will not survive the winter outdoors. The ground freezes deep enough to turn the fleshy rhizomes into mush. In these cooler climates, you must treat cannas as "tender perennials." This means you enjoy them all summer, dig them up in the fall, and store them indoors where they stay dormant but protected from freezing.
Key Takeaway: Always check your specific hardiness zone before winter arrives. If you are in zone 6 or colder, plan to bring your cannas inside to ensure they return next year.
Why Canna Rhizomes Need Winter Protection
It is helpful to understand what is happening inside the plant as winter approaches. Cannas grow from rhizomes, which are thick, underground stems that store energy and food. Think of the rhizome as a battery that powers the leaves and flowers.
When the temperature drops, the leafy part of the plant eventually dies back. If the rhizome itself freezes, the water inside its cells expands and breaks the cell walls. This leads to rot once the ground thaws. By protecting the rhizome from freezing, you are preserving that stored energy for next year's growth.
Another benefit of winter care is that it gives you a chance to see how much your plants have grown. Canna rhizomes are prolific. A single small rhizome planted in May can easily grow into a massive clump by October. Digging them up allows you to divide these clumps, effectively giving you "free" plants to use in other parts of your yard or to share with friends.
When to Start the Overwintering Process
Timing is everything when it comes to preparing cannas for winter. You want to give the plants as much time as possible to store energy, but you must act before the ground freezes solid.
The best signal to look for is the first light frost. You will notice that the lush green or burgundy leaves suddenly turn black or dark brown and look limp. This might look a bit sad at first, but it is actually a helpful sign from nature. The frost tells the plant to stop sending energy to the leaves and start moving everything down into the rhizome for the winter.
Once the foliage has been "zapped" by the frost, you can begin the process. If you live in an area where a hard freeze (where the ground itself begins to freeze) happens quickly after the first frost, try to get your cannas out of the ground within a week or two of the foliage dying back. This winter storage guide offers additional guidance for tender bulbs and tubers.
If you prefer to keep your garden looking tidy, you can cut the stalks down to about four inches above the ground immediately after the frost. This makes the clumps much easier to handle and move.
What to do next:
- Monitor your local weather forecast for the first frost warning.
- Once the leaves turn black, cut the stalks back to 4–6 inches.
- Gather your tools: a garden fork or spade, a brush, and storage containers.
- Prepare a workspace in a garage or shed where you can clean the rhizomes.
Step-by-Step Guide to Digging Canna Rhizomes
Digging up cannas is a simple and rewarding task. Because the rhizomes grow relatively close to the surface, you don't have to dig very deep holes. However, you do want to be careful not to slice through the rhizomes with your shovel.
Start by placing your garden fork or spade about a foot away from the base of the stalks. Gently push the tool into the soil and pry upward to loosen the earth. Work your way around the entire clump, loosening it from all sides. Once the soil is loose, you can usually lift the entire mass out of the ground by grasping the remaining stalks.
Once the clump is out, shake off the excess soil. You don't need to get them perfectly clean yet. It is often easier to let the soil dry for a few hours, at which point it will crumble away more easily. Avoid using a high-pressure hose to wash the rhizomes. While it might seem like a good way to clean them, excess moisture can encourage fungal growth or rot during storage. If the soil is very muddy, you can use a gentle stream of water, but make sure the rhizomes dry completely afterward.
As you handle the rhizomes, you will notice they are quite brittle. It is common for pieces to snap off. Don't worry—as long as a piece has at least one "eye" (a small bump or bud where new growth starts), it can grow into a full plant next year.
Curing and Preparing for Storage
Before you tuck your cannas away for the winter, they need a short period of "curing." This is just a fancy term for letting them air dry. Curing the rhizomes helps the outer skin of the rhizome toughen up, which makes it more resistant to rot and disease.
Place your cleaned rhizomes in a dry, frost-free area like a garage, shed, or covered porch. Spread them out in a single layer so air can circulate around them. Let them sit for two to three days. During this time, any remaining soil will dry up and can be lightly brushed off.
While the rhizomes are drying, take a moment to inspect them. Look for any soft spots, signs of insect damage, or mold. If you find a small area of rot, you can often cut it away with a clean, sharp knife until you reach firm, white flesh. If a rhizome is completely soft or smells bad, it is best to discard it so it doesn't spread rot to the healthy ones.
This is also the perfect time for labeling. Since many canna varieties look identical once they are just bare rhizomes, use a permanent marker to write the variety name or color directly on the skin of the rhizome. You will be very glad you did this when planting time arrives in the spring!
Key Takeaway: Curing for 2–3 days is a simple step that prevents many common storage problems. Always label your rhizomes before putting them into containers.
Best Methods for Winter Storage
The goal of storage is to keep the rhizomes dormant, cool, and just slightly moist enough that they don't shrivel up like raisins. There are several ways to do this, and the best method often depends on what supplies you have on hand.
Storing in Peat Moss or Vermiculite
One of the most popular methods is to place the rhizomes in a cardboard box or plastic bin filled with slightly damp peat moss, coco coir, or vermiculite. These materials hold just enough moisture to keep the rhizomes plump but allow for enough airflow to prevent rot.
Layer the material in the bottom of the container, place the rhizomes on top (not touching each other if possible), and cover them with more material. If you use a plastic bin, leave the lid slightly ajar or drill a few small holes in the sides to prevent moisture from building up inside.
The Newspaper Wrap Method
If you don't have peat moss, common newspaper is an excellent alternative. Simply wrap each rhizome or small clump in a few sheets of dry newspaper. The paper acts as an insulator and absorbs any excess moisture that might lead to rot. Place the wrapped bundles in a crate or a breathable bag. This method is very tidy and makes it easy to check on the plants during the winter.
Using Wood Shavings or Sawdust
Pine shavings, often sold as animal bedding at garden or farm supply stores, work very much like peat moss. They are inexpensive, easy to handle, and provide great insulation. This is a favorite choice for gardeners with large collections because it is very cost-effective.
Finding the Perfect Storage Location
Where you put your containers is just as important as how you pack them. Cannas need a spot that stays consistently cool but never freezes. The ideal temperature range is between 40°F and 50°F. See this guide to where to store canna bulbs for additional location ideas.
If the storage area is too warm (above 60°F), the cannas might think it is spring and start to grow in the dark. This wastes the plant's energy and results in weak, pale sprouts. If the area is too cold (below 35°F), you risk the rhizomes freezing.
Good storage locations include:
- Unheated basements or crawl spaces
- An insulated garage that stays above freezing
- A cool, dark closet in a mudroom
- A root cellar
Avoid storing cannas near a furnace, water heater, or any other heat source. These spots are usually too dry and warm, which will cause the rhizomes to shrivel.
Winter Maintenance and Troubleshooting
Even though the cannas are dormant, they benefit from a quick "wellness check" once a month. This only takes a few minutes but can save your entire collection. The monthly maintenance recommendations can help you identify problems early.
Open your containers and feel a few of the rhizomes. They should feel firm, like a fresh potato. If they feel extremely dry or start to look shriveled, use a spray bottle to lightly mist the packing material (the peat moss or newspaper). You don't want it to be wet—just slightly damp to the touch.
If you notice any rhizomes that have turned soft, mushy, or have fuzzy mold growing on them, remove them immediately. Rot can spread quickly in a confined container, so removing the "bad apples" protects the rest of the bunch. If a large clump has a small spot of mold, you can often wipe it off with a cloth dipped in a very weak solution of water and vinegar, then let it dry before putting it back.
If you see green tips starting to poke out in January or February, your storage area is likely too warm. Try moving the containers to a cooler spot to keep the plants asleep until the proper planting time.
Overwintering Cannas in Containers
Many gardeners prefer to grow cannas in large pots on patios or decks. If this sounds like your garden, you have a very easy path for winter care.
When the frost hits the foliage, cut the stalks back to the soil level as usual. Instead of digging the rhizomes out, you can simply move the entire pot into a cool, frost-free area like a garage or basement. Stop watering the pot entirely. The soil will dry out, and the cannas will go into a deep sleep right where they are.
In the spring, you can bring the pot back outside, give it a fresh layer of compost or fertilizer, and start watering again. Every two or three years, you should still tip the pot over and divide the rhizomes, as they will eventually become "pot-bound" and stop blooming as well.
Key Takeaway: Container-grown cannas can be overwintered in their pots. Just move the pot to a cool, dry place and stop watering until spring.
How to Handle Cannas in Warmer Climates
If you live in Zone 8 or warmer, your "winter work" is much simpler. In these regions, cannas are happy to stay in the ground. However, a little bit of care goes a long way in ensuring they come back stronger than ever.
Once the foliage dies back or becomes unsightly, cut the stalks down to about two or three inches. Apply a 3- to 4-inch layer of organic mulch over the top of the planting area. Shredded leaves, straw, or bark mulch all work well. This layer acts like a blanket, protecting the rhizomes from any surprise cold snaps and helping to maintain consistent soil moisture.
In these warmer zones, the biggest risk to cannas in winter isn't actually the cold—it's the wet. If your garden has heavy clay soil that stays soggy all winter, the rhizomes can rot. If you live in a very rainy winter climate, make sure your cannas are planted in a spot with excellent drainage, or consider planting them in raised beds.
Waking Your Cannas Up in Spring
As the days grow longer and the soil begins to warm, it is time to start thinking about the upcoming growing season. You have two choices for how to restart your cannas.
Option 1: Direct Planting
The simplest method is to wait until the danger of frost has passed and the soil has warmed to at least 60°F. In most areas, this is about the same time you would plant tomatoes. Dig a shallow hole, lay the rhizome horizontally with the "eyes" pointing up, and cover it with 3 to 4 inches of soil.
Option 2: Starting Indoors
If you live in a northern climate with a short growing season, you might want to give your cannas a head start. About 4 to 6 weeks before the last frost, you can plant the rhizomes in pots indoors. Place them in a sunny window or under grow lights. By the time it is warm enough to move them outside, you will have established plants with several inches of growth, leading to earlier blooms in the summer.
At Longfield Gardens, we have found that giving cannas this extra few weeks of indoor growth really helps them reach their full potential, especially for the taller varieties that need a long season to flower.
Realistic Expectations for Canna Success
While cannas are generally very hardy and easy to save, it is important to remember that they are living things. Sometimes, despite your best efforts, a few rhizomes might not make it through the winter. This is usually due to factors beyond your control, like an unusually damp autumn or a hidden pocket of rot that started before you dug them up.
Don't be discouraged if you lose one or two. Because cannas multiply so quickly, the healthy ones will usually produce enough new growth to fill the gaps. Gardening is a constant learning process, and every winter you spend caring for your bulbs makes you a more skilled gardener.
Focus on the basics: get the timing right, keep them cool and dry, and check on them occasionally. These simple steps are usually all it takes to enjoy those tropical vibes year after year.
Conclusion
Canna lilies are some of the most rewarding plants you can add to your landscape. Their bold textures and brilliant colors provide a tropical punch that lasts from the heat of July through the first whispers of fall. By taking the time to understand your hardiness zone and following a few simple steps for winter storage, you can protect these beautiful plants and watch your collection grow over time.
We are proud to provide high-quality rhizomes and the support you need to make your garden a success. Whether you are letting your cannas rest in the ground or tucking them into a box of peat moss in the garage, the effort is well worth the spectacular display that awaits you next summer.
Key Takeaway Summary:
- Identify your hardiness zone to decide if you need to dig or mulch.
- Wait for the first frost to signal the start of dormancy.
- Cure rhizomes for a few days before storing in a cool, dry place.
- Check your stored bulbs monthly to ensure they remain healthy and firm.
Gardening is about the joy of the journey and the beauty of the results. We invite you to explore spring-planted summer-blooming bulbs at Longfield Gardens and start planning your next tropical oasis today.
FAQ
Can I leave cannas in the ground if I live in Zone 7?
Yes, you can often leave cannas in the ground in Zone 7, but it involves some risk. To increase their chances of survival, plant them in a sheltered spot with good drainage and cover the area with 6 to 8 inches of mulch after cutting back the stalks. Many gardeners in this zone dig up at least a few rhizomes as an "insurance policy" in case of an exceptionally cold winter.
What should I do if my stored canna rhizomes look shriveled?
If your rhizomes look very wrinkled or feel slightly soft due to dryness, they likely need a tiny bit of moisture. Use a spray bottle to lightly mist the packing material (like peat moss or newspaper) surrounding them. Avoid soaking the rhizomes directly; the goal is to create a slightly humid environment that stops them from losing more moisture.
Do I have to wait for a frost before digging up my cannas?
While you don't have to wait for a frost, it is highly recommended. The frost kills the foliage and sends a signal to the plant to move its energy and nutrients down into the rhizome for winter storage. This process results in a stronger, healthier rhizome that is more likely to sprout vigorously the following spring. For more detail, see this guide to digging and storing canna bulbs.
How do I tell which side of the canna rhizome is "up" when planting?
Look for the "eyes" or small, pointed buds on the surface of the rhizome. These are the points where new stems will emerge. When planting, lay the rhizome horizontally in the soil with these eyes pointing toward the sky. If you aren't sure which side is which, don't worry too much—cannas are very determined and will eventually find their way to the surface even if planted sideways.
