Table of Contents
- Introduction
- Understanding Canna Lily Hardiness
- Can You Leave Canna Bulbs in the Ground?
- When to Dig Up Cannas
- How to Dig and Clean Canna Rhizomes
- The Curing Process: Preparing for Winter Sleep
- Storage Strategies: Peat Moss, Newspaper, and Boxes
- Overwintering Cannas in Containers
- Monitoring Your Rhizomes Through Winter
- Dividing Cannas: How to Get Free Plants
- Waking Them Up: Spring Transition
- Conclusion
- FAQ
Introduction
There is nothing quite like the tropical flair that canna lilies bring to a summer garden. With their towering stems, oversized leaves, and vibrant blooms in shades of sunset orange and fiery red, they transform any backyard into an exotic retreat. At Longfield Gardens, we love how these easy-to-grow plants provide months of color and texture with very little fuss. However, as the temperatures begin to dip in the fall, many gardeners find themselves wondering if these tropical beauties will return the following year. If you’re looking to build a bigger display next season, explore our Canna Assorted Mix - Bulk Offer.
The answer to whether your canna bulbs will survive winter depends mostly on where you live and a few simple steps you take as the season changes. In warmer climates, they can often stay right in the ground, but in most of the United States, they require a bit of extra care to make it through the cold months. Use the Hardiness Zone Map to check your local conditions.
We will cover exactly how to identify if your climate is safe for outdoor overwintering and provide a straightforward path for those who need to bring their plants indoors. By understanding the simple needs of these resilient rhizomes, you can ensure your garden stays lush and colorful every summer. Successful overwintering is all about timing and a few basic storage rules. For a broader overview, start with All About Cannas.
Understanding Canna Lily Hardiness
The first step in determining if your canna bulbs will survive winter is knowing your USDA plant hardiness zone. Cannas are tropical and subtropical plants by nature. In their native habitats, they grow year-round without a dormant period. In the United States, they are generally considered perennial in zones 8 through 10. For a taller statement in the garden, browse Tall Cannas.
If you live in zone 7, you are in a "swing" region. In a mild winter, cannas may survive in the ground if they are given a heavy layer of protection. However, in zones 6 and colder, the freezing temperatures will almost certainly reach the rhizomes, causing them to turn to mush. When water inside the plant cells freezes, it expands and ruptures the cell walls. For a fleshy structure like a canna rhizome, this is fatal.
It is helpful to think of a canna "bulb" not as a true bulb, like a tulip, but as a rhizome. A rhizome is a thick, fleshy underground stem that stores energy and water. This storage capacity is what makes them so vigorous in the summer, but it also makes them vulnerable to freezing. Because they are mostly water, they simply cannot withstand a hard, deep freeze.
Key Takeaway: Cannas are naturally hardy in zones 8–10. If you live in zone 7 or lower, you will likely need to provide extra protection or dig them up for the winter to ensure they return.
Can You Leave Canna Bulbs in the Ground?
Whether you can leave your cannas in the ground depends on the severity of your local winter and the drainage of your soil. Even in warmer zones, wet soil can be just as dangerous as cold air. If the ground remains soggy and cold for several months, the rhizomes may rot before the spring sun can wake them up. For a space-saving option, see Short Cannas.
Overwintering in Zones 8 to 10
In these southern regions, cannas are incredibly reliable. You can simply cut the foliage back to the ground after the first frost has turned the leaves brown. Many gardeners choose to add a 2-to-3-inch layer of mulch, such as shredded bark or pine needles, over the site. This mulch acts as a blanket, keeping the soil temperature consistent and protecting the "eyes" (growth points) of the rhizomes from sudden temperature spikes.
The Zone 7 Strategy
If you are in zone 7, you can often "bank" your cannas. This involves cutting the stems down and applying a much thicker layer of mulch—anywhere from 6 to 10 inches deep. This thick layer of insulation can prevent the frost from penetrating the soil. However, this is always a bit of a gamble. For a middle-size planting, Medium Cannas are a good fit.
Risks of Rot
The biggest enemy of a dormant canna rhizome is moisture. When the plant is not actively growing, it isn't "drinking" water from the soil. If the rhizome sits in a pool of cold water all winter, fungi and bacteria can take over. If you have poorly draining soil, it is often safer to dig the plants up even if your zone is technically warm enough for them to stay outside.
What to do next:
- Check your USDA hardiness zone using your zip code.
- Observe your garden's drainage; if water puddles in the area after rain, consider digging the rhizomes.
- If staying in the ground, gather mulch materials like straw, leaves, or wood chips in late autumn.
When to Dig Up Cannas
Timing is the most important factor when it is time to bring your cannas inside. You want to leave them in the ground for as long as possible so the rhizomes can store maximum energy for next year. The foliage is the "solar panel" for the plant, and it continues to feed the rhizome right up until the end of the season.
The signal to start the process is the first light frost. You will notice the lush green leaves suddenly turn black or dark brown and look wilted. This is perfectly normal. This first touch of cold tells the plant to go dormant. While the foliage is damaged, the ground is still warm, and the rhizomes themselves are safe.
You should aim to dig your cannas after this first frost but before the ground freezes solid. A deep freeze that reaches several inches into the soil will damage the rhizomes. In most northern states, this window usually occurs in October or November. For a step-by-step refresher, read How to Overwinter Canna Lily Bulbs: A Step-by-Step Guide. Keeping an eye on the local weather forecast is the best way to ensure you don't wait too long.
Key Takeaway: Wait for the first frost to turn the leaves brown before digging. This ensures the plant has stored all the energy it can for the following season.
How to Dig and Clean Canna Rhizomes
Digging up cannas is a satisfying autumn task. Because canna rhizomes grow relatively close to the soil surface and spread outward, they are usually easier to lift than deep-rooted perennials. However, they can be quite heavy once they have multiplied throughout the summer.
The Right Tools
A garden fork (sometimes called a digging fork) is the best tool for the job. The tines allow you to lift the soil and the plant without the high risk of slicing through the rhizomes that a flat shovel blade carries. If you only have a shovel, be sure to start your digging several inches further away from the base of the plant than you think you need to. For more digging details, see How to Dig Up and Store Canna Lily Bulbs.
Lifting the Clumps
- Cut the Stems: Start by cutting the stalks down to about 2 to 4 inches above the soil line. This gives you a "handle" to grab while removing the excess foliage from your workspace.
- Loosen the Soil: Insert your fork into the ground about 6 to 8 inches away from the main stems. Gently pry upward all the way around the clump to loosen the roots.
- Lift: Once the soil is loose, lift the entire mass out of the ground. You may be surprised to find that the single rhizome you planted in the spring has turned into a massive cluster of five or ten new ones.
Cleaning the Rhizomes
Once the clump is out of the ground, shake it gently to remove large chunks of soil. Use your hands to brush away the remaining dirt. It is important to be gentle; while rhizomes look tough, they can be bruised or "skinned" if handled roughly.
Avoid using a high-pressure hose to wash the rhizomes unless your soil is extremely mucky or you grew them in a water feature. Excess water at this stage can lead to rot during storage. If you do use water to clean them, they must be dried thoroughly before they are packed away.
What to do next:
- Clear away the dead foliage to make the base of the plant visible.
- Use a digging fork to lift the clumps, starting wide to avoid damage.
- Shake off loose soil but keep the rhizomes dry.
The Curing Process: Preparing for Winter Sleep
Curing is a critical step that many gardeners skip. Just like onions or potatoes, canna rhizomes benefit from a short drying period before they go into long-term storage. This process allows the outer "skin" of the rhizome to toughen up, which helps it resist diseases and prevents it from drying out too quickly over the winter.
After you have dug and cleaned your rhizomes, move them to a dry, well-ventilated area that is protected from frost. A garage, a shed, or even a covered porch works well. Spread the rhizomes out in a single layer so that air can circulate around them. For more on storage timing, see How Long Can You Store Canna Lily Bulbs? Storage Tips.
Let them sit for about 3 to 7 days. During this time, any remaining soil will dry up and fall off easily, and the cut ends of the stems will callus over. A callused end acts as a seal, keeping moisture inside the rhizome and keeping rot-causing bacteria out. If the weather is particularly damp, you may need an extra day or two. The rhizomes should feel firm and dry to the touch, not shriveled or soft.
Key Takeaway: "Curing" your rhizomes in a dry spot for a few days toughens their skin and significantly reduces the risk of rot during the winter months.
Storage Strategies: Peat Moss, Newspaper, and Boxes
Once your cannas are cured, it is time to pack them away for their winter nap. The goal is to keep them in a "goldilocks" environment: not so wet that they rot, but not so dry that they shrivel up and die. We find that providing a little bit of insulating material is the best way to achieve this balance.
Choosing Your Container
Cardboard boxes, plastic crates, or heavy-duty paper bags are all excellent choices. Avoid airtight plastic containers or sealed plastic bags, as these trap moisture and almost always lead to mold and rot. You want the rhizomes to be able to "breathe" just a little bit.
Packing Material
You should layer your rhizomes with a dry or very slightly damp material. Popular options include:
- Peat Moss: This is a classic choice because it holds just a tiny bit of moisture while remaining airy.
- Vermiculite or Perlite: These sterile minerals are great for preventing fungal growth.
- Shredded Newspaper or Wood Shavings: These are affordable, easy-to-find options that provide good insulation.
- Dry Leaves or Pine Needles: If you have these in your yard, they work well as a natural packing material.
Place a layer of your chosen material in the bottom of the box, then a layer of rhizomes (not touching each other if possible), and then more material. Repeat until the box is full. Label the box with the variety name or color so you know what you are planting in the spring.
The Ideal Environment
Store your boxes in a cool, dark, and dry place. The temperature should ideally stay between 40°F and 55°F. An unfinished basement, a crawl space, or a corner of an attached garage that doesn't freeze is perfect. If the temperature gets too warm (above 60°F), the cannas may try to start growing in the dark, which will exhaust their energy.
What to do next:
- Select a breathable container like a cardboard box or crate.
- Gather packing material such as peat moss or shredded paper.
- Layer the rhizomes so they aren't touching, and label the varieties.
Overwintering Cannas in Containers
If you grow your cannas in large pots on your patio, the winter process can be even simpler. You don't necessarily have to dig the rhizomes out of the soil. Instead, you can overwinter the entire pot. This is a great time-saver for busy gardeners. For more ideas on growing them in pots, see Best Summer Bulbs for Containers.
When the frost hits and the foliage dies back, cut the stems down to the soil level as you would with garden-planted cannas. Instead of digging, simply move the entire container into a frost-free area like a basement or garage. The soil in the pot provides a natural layer of insulation for the rhizomes.
During the winter, you do not need to water the pot. The goal is to keep the soil dry so the plant stays in a deep sleep. In the spring, you can bring the pot back out into the sun, give it a fresh layer of compost or a bit of fertilizer, and start watering again. Eventually, the pot will become crowded as the rhizomes multiply, and you will need to tip it out and divide the plants every two or three years to keep them healthy.
Key Takeaway: Container-grown cannas can stay in their pots over winter. Just move the pot to a cool, dark, frost-free location and stop watering until spring.
Monitoring Your Rhizomes Through Winter
Successful overwintering isn't a "set it and forget it" task. It is a good idea to check on your stored canna bulbs about once a month. This small effort can save your entire collection if an issue arises.
What to Look For
When you open your storage boxes, look for any signs of soft spots or fuzzy mold. If you find a rhizome that is starting to rot, remove it immediately. Rot can spread from one rhizome to another if they are in contact. If only a small tip of a large rhizome is soft, you can sometimes cut that part off with a clean knife and let the healthy portion dry out before putting it back.
If the rhizomes look extremely shriveled and feel lightweight, they might be getting too dry. In this case, you can lightly mist the packing material with a spray bottle of water. You don't want it to be wet—just a tiny bit of humidity to stop the dehydration.
Managing Pests
Occasionally, mice or other small rodents might find your storage boxes and decide that canna rhizomes look like a tasty winter snack. If you notice signs of chewing, you may need to move your boxes to a more secure location or place them inside a crate with a wire mesh lid that allows air in but keeps critters out.
What to do next:
- Mark your calendar to check the storage boxes once a month.
- Remove any rhizomes that show signs of rot or mold.
- Lightly mist the packing material only if the rhizomes feel excessively shriveled.
Dividing Cannas: How to Get Free Plants
One of the best things about cannas is how quickly they multiply. A single rhizome planted in May can easily become a dozen by October. Winter storage is the perfect time to evaluate your "harvest" and divide the clumps. This is a simple, cost-effective way to fill more of your garden or share plants with friends and neighbors. If you want a dramatic variety for next summer, Canna Tall Tropicanna is a standout option.
When to Divide
You can divide your cannas either in the fall before you put them into storage or in the spring before you plant them. Many gardeners prefer the spring because it is easier to see the "eyes" (the small bumps where new stems will grow) once the plants begin to wake up. However, if your clumps are massive and hard to store, dividing them in the fall is perfectly fine.
How to Divide
Cannas are very forgiving. You can often pull the clumps apart with your hands. If the connection is too thick, use a clean, sharp knife to cut them. The only rule is that every piece you intend to plant needs to have at least one or two "eyes." These look like the eyes on a potato. As long as a piece of rhizome has an eye and some fleshy mass to support it, it will grow into a full-sized plant.
If you make cuts in the fall, it is a good idea to let the pieces dry for a day so the cut surfaces can callus before they go into storage. This prevents moisture from escaping and pathogens from entering.
Key Takeaway: Cannas multiply rapidly. Dividing the rhizomes every year or two gives you an endless supply of new plants to expand your garden.
Waking Them Up: Spring Transition
As the days get longer and the threat of frost passes, it is time to bring your cannas out of storage. This is an exciting moment for any gardener, as it marks the beginning of a new growing season. Depending on where you live, you have two choices for how to start your plants. If you like a vivid, mid-size option, Canna Medium Banana Punch is another choice.
Starting Indoors (Pre-Sprouting)
If you live in a northern climate with a short growing season, you can give your cannas a head start by "waking them up" indoors about 4 to 6 weeks before the last frost date. Plant the rhizomes in pots with fresh potting soil and place them in a warm, sunny window. This gives them a chance to develop roots and start sending up foliage. By the time the weather is warm enough to move them outside, you will already have a small plant rather than just a dormant bulb.
Direct Planting
In regions with a longer summer, you can simply wait until the soil has warmed up to about 60°F and plant the rhizomes directly into the garden. Cannas love heat, so there is no rush to get them in the ground while the soil is still chilly. They won't start growing vigorously until the ground is truly warm.
When planting, place the rhizomes horizontally about 4 to 5 inches deep. Space them about 1 to 2 feet apart, depending on the variety's expected size. Make sure the "eyes" or any new sprouts are pointing upward. Water them well after planting to settle the soil around the roots.
What to do next:
- Determine your local last frost date to time your planting.
- Decide if you want to pre-sprout in pots for an earlier bloom.
- Wait for the soil to warm to at least 60°F before direct planting in the garden.
Conclusion
Canna lilies are some of the most rewarding plants you can grow, offering a high-impact look with very manageable requirements. While they may not naturally survive the winter in most of the country, the process of digging and storing them is a simple autumn ritual that ensures your investment grows year after year. By following the easy steps of waiting for the first frost, curing the rhizomes, and storing them in a cool, dry place, you can enjoy these tropical treasures for many seasons to come.
At Longfield Gardens, we want every gardener to feel confident in their ability to maintain a beautiful and vibrant yard. Whether you choose to mulch your cannas in the ground or pack them away in the basement, the result is the same: a stunning display of summer color that only gets better as the plants multiply. Gardening is a journey of learning and growth, and mastering the winter care of cannas is a great way to build your skills.
- Know your hardiness zone to decide if you should dig or mulch.
- Wait for the first frost before starting your winter prep.
- Store rhizomes in a cool, dark place with breathable packing material.
- Check your stored plants monthly to ensure they stay healthy.
We are here to support your gardening success with quality plants and practical advice. Start planning your summer color today by exploring our canna varieties at Longfield Gardens.
FAQ
How cold is too cold for canna bulbs?
Canna rhizomes can generally withstand soil temperatures down to about 15°F for short periods, but they will freeze and rot if the ground stays frozen for a long time. In terms of air temperature, the foliage will die back at the first sign of frost (32°F), but the rhizomes are safe until the ground itself begins to freeze. To be safe, most gardeners dig them up once the nighttime temperatures consistently drop into the 30s.
Do I need to water my cannas while they are in storage?
Generally, no. Canna rhizomes should remain dormant and relatively dry throughout the winter. If the storage area is very dry and the rhizomes begin to look severely shriveled like a raisin, you can lightly mist the packing material with a little water. However, you should never make the material wet, as this is the most common cause of rot during the winter months.
Can I store cannas in a refrigerator?
It is not recommended to store canna rhizomes in a refrigerator. Most refrigerators are kept at 35°F to 38°F, which is a bit too cold for tropical cannas and can cause tissue damage. Additionally, refrigerators are often very dry environments that can dehydrate the fleshy rhizomes. A cool basement or an attached garage that stays between 40°F and 55°F is a much better environment for them.
Why did my stored canna bulbs turn soft and mushy?
If your rhizomes are soft and mushy, it is a sign of rot, which is usually caused by too much moisture or a lack of airflow during storage. This can happen if the rhizomes weren't dried (cured) properly before being packed away, or if they were stored in an airtight plastic container. To prevent this, ensure they are dry to the touch before storing and use breathable containers like cardboard boxes or paper bags. For a step-by-step refresher, read How to Dig Up and Store Canna Lily Bulbs.