Table of Contents
- Introduction
- Understanding Canna Lily Hardiness
- When to Start the Winterizing Process
- Preparing the Plants for Digging
- How to Lift Canna Rhizomes Safely
- Cleaning and Inspecting the Rhizomes
- The Importance of Curing
- Dividing Rhizomes: Now or Later?
- Choosing the Best Storage Medium
- Packing Your Cannas for the Winter
- Finding the Perfect Storage Location
- Monitoring Your Rhizomes Through Winter
- Winterizing Cannas in Containers
- Bringing Cannas Out of Storage
- Common Myths About Winterizing Cannas
- Regional Variations for Winter Care
- Final Steps for Success
- Conclusion
- FAQ
Introduction
Canna lilies are the undisputed stars of the summer garden. Their oversized, tropical foliage and vibrant blossoms bring a touch of the exotic to any backyard or patio. Whether you love the fiery reds of a classic variety or the variegated patterns of modern cultivars, these plants offer a spectacular reward for very little effort. At Longfield Gardens, we enjoy how these bold plants transform a simple landscape into a lush retreat.
If you live in a region with cold winters, you might wonder how to keep these tropical beauties alive once the temperature drops. Fortunately, winterizing canna lily bulbs—which are technically called rhizomes—is a straightforward process that any gardener can master. By following a few simple steps, you can save your favorite canna collection from the frost and enjoy them again next year. This guide is for anyone who wants to preserve their canna collection and ensure a successful start for the next growing season.
The secret to success lies in timing and proper storage conditions. With the right approach, your cannas will rest comfortably through the winter months, ready to burst back into life when the soil warms up in spring.
Understanding Canna Lily Hardiness
To decide if you need to dig up your plants, you first need to know your USDA hardiness zone. Canna lilies are tropical perennials. They are naturally adapted to warm climates where the ground never freezes. In the United States, they are generally hardy in zones 8 through 11. If you live in these warm areas, your cannas can usually stay in the ground year-round with minimal protection.
For gardeners in zones 3 through 6, the winter ground temperatures are far too cold for cannas to survive. In these regions, digging them up is a necessity. Zone 7 is often considered the "middle ground." In a mild year, cannas in zone 7 might survive if they are heavily mulched. However, many gardeners in zone 7 choose to lift their bulbs anyway to be safe. We recommend digging them up if you have any doubt about the severity of the coming winter. To compare your garden with the official map, check the USDA hardiness zone map.
A "rhizome" is the part of the plant you will be storing. While many people call them "bulbs," they are actually thick, fleshy underground stems, or canna rhizomes. These stems store energy for the plant. During the winter, the goal is to keep these rhizomes dormant. They should stay cool enough that they do not sprout, but warm enough that they do not freeze.
When to Start the Winterizing Process
Timing is everything when it comes to lifting canna rhizomes. You want to give the plant as much time as possible to store energy, but you must act before the ground freezes solid. The best signal to start is the first light frost of autumn.
A light frost will usually turn the lush green leaves of your cannas brown or black. This might look disappointing at first, but it is actually a helpful part of the plant's life cycle. This "cold snap" tells the plant that the growing season is over. It signals the rhizome to enter a state of dormancy. Once the foliage has blackened, the energy from the leaves moves down into the rhizome.
Wait a few days after the first frost before you begin digging. This allows the plant to settle into its dormant state. However, do not wait until the ground begins to freeze. A hard freeze that penetrates several inches into the soil can damage or kill the rhizomes. In most northern states, the ideal window for digging is late September through October.
Key Takeaway: The first frost is your green light to start. Once the leaves turn dark and wilted, you have about a week or two to get the rhizomes out of the ground before a deep freeze arrives.
Preparing the Plants for Digging
Before you reach for your shovel, you need to clear away the spent foliage. This makes the digging process much easier and reduces the amount of garden debris you have to handle.
Use a clean pair of garden shears or a sharp knife to cut the stalks. Aim for a height of about 3 to 6 inches above the soil line. Leaving a small portion of the stalk attached gives you a convenient "handle" to hold onto while you move the rhizomes. It also helps you identify which side is the top of the plant later on.
Once the stalks are cut, clear away any mulch or fallen leaves from around the base of the plant. This gives you a clear view of the soil so you can see where the rhizomes are located. Because cannas grow outward in clumps, they can spread further than you might expect. Having a clean workspace prevents accidental damage to the fleshy roots.
Tools for Success
- Garden Fork: This is the best tool for lifting cannas. The tines allow you to loosen the soil without slicing through the rhizomes.
- Spade or Shovel: If you don't have a fork, a sharp spade works well. Just be sure to start your cuts far away from the center of the plant.
- Garden Shears: To cut back the heavy stalks.
- Garden Gloves: To protect your hands from damp soil and sharp leaf edges.
How to Lift Canna Rhizomes Safely
Lifting canna rhizomes requires a gentle touch. Unlike rocks or solid roots, rhizomes are quite brittle and can snap if they are pried too hard. They are also susceptible to bruising, which can lead to rot during the winter months.
Start by inserting your garden fork into the soil about 8 to 12 inches away from the base of the stems. This distance ensures that you stay clear of the main clump. Push the fork deep into the ground and gently rock it back and forth to loosen the soil. Work your way around the entire perimeter of the plant in a circle.
As the soil loosens, you will feel the clump start to lift. Use the fork to gently pry the entire mass upward. Avoid pulling on the remaining stalks, as they can break off from the rhizome. Instead, lift from underneath with your tool. Once the clump is free from the earth, lift it out and set it on the grass or a tarp.
If you have a very large, established patch of cannas, the root mass might be quite heavy. Don't be afraid to lift it in sections if necessary. While we want to keep the rhizomes intact, it is perfectly fine if a few pieces snap off during the process. These smaller pieces can often be saved and planted individually in the spring.
What to Do Next
- Cut the stalks: Trim them down to 3–6 inches above the soil.
- Circle the plant: Loosen the soil 12 inches away from the stems.
- Lift gently: Use a garden fork to pry the clump from underneath.
- Shake off excess: Remove the largest clumps of soil by hand.
Cleaning and Inspecting the Rhizomes
Once the rhizomes are out of the ground, they will likely be covered in damp soil. It is important to remove this soil before storage, as it can harbor pests or hold too much moisture against the skin of the plant.
You have two options for cleaning. The first is to simply use your hands to brush off the loose dirt. This is often the safest method if your soil is sandy and falls away easily. The second option is to use a garden hose to gently wash the soil off. If you use water, be sure to use a low-pressure setting. High pressure can tear the delicate skin of the rhizome.
After cleaning, take a close look at your harvest. Healthy canna rhizomes should feel firm to the touch, similar to a fresh ginger root or a potato. If you find any parts that feel soft, mushy, or hollow, trim them away with a clean knife. These are signs of rot, and if left on the plant, the rot can spread to the healthy sections during the winter.
You may also notice small, white or pinkish "nubs" on the rhizomes. These are the "eyes," or growth points, where next year's stems will emerge. The more eyes a rhizome has, the more stalks it will produce. Protecting these eyes is vital for a lush garden next summer.
The Importance of Curing
Curing is a step that many beginner gardeners skip, but it is essential for long-term storage success. Curing is the process of allowing the outer skin of the rhizome to dry and toughen up. This creates a natural barrier against fungus and prevents the internal moisture from evaporating too quickly.
To cure your cannas, find a dry, well-ventilated area that is protected from the elements. A garage, a garden shed, or a covered porch works perfectly. Spread the rhizomes out in a single layer on a piece of cardboard, newspaper, or a mesh screen. Do not stack them on top of each other, as they need good airflow to dry properly.
The curing process usually takes about 3 to 7 days, depending on the humidity. You will know they are ready when the outer skin looks dull and feels slightly papery. If you washed your rhizomes with a hose, they may need the full week to ensure all the nooks and crannies are dry.
"Proper curing acts like a shield for your plants. It helps the rhizomes resist the damp conditions of storage and keeps them healthy until spring."
Dividing Rhizomes: Now or Later?
Over a single growing season, a small canna rhizome can grow into a massive clump. Many gardeners wonder if they should divide these clumps before putting them into winter storage.
The truth is that you can do it at either time. Dividing in the fall saves space in your storage containers. It also allows you to inspect the interior of the rhizomes for any signs of disease. If you choose to divide now, make sure each piece has at least two or three healthy "eyes." Use a sharp, sterilized knife to make clean cuts. We recommend letting the cut ends dry for an extra day or two so they can form a "callus" before being packed away.
Alternatively, you can store the entire clump as it is and wait until spring to divide it. This is often easier for busy gardeners. In the spring, it is also easier to see which eyes are the most vigorous as they begin to wake up. At Longfield Gardens, we often find that waiting until spring is the most reliable method for beginners, as the rhizomes are less likely to dry out if they remain in a large clump.
Choosing the Best Storage Medium
Canna rhizomes cannot just be tossed into a plastic bin. If they are exposed to the air, they will shrivel and dry out. If they are trapped in an airtight container, they will rot. The goal is to provide a "breathable" environment that maintains just a tiny bit of moisture.
The most popular materials for packing cannas include:
- Peat Moss: This is an excellent choice because it is naturally acidic and helps inhibit fungal growth. It holds just enough moisture to keep the rhizomes from desiccating.
- Vermiculite or Perlite: These lightweight minerals provide great aeration and are very clean to work with.
- Sawdust or Wood Shavings: These are affordable and effective, though they should be uncurated and free of chemicals.
- Newspaper: If you don't have bulk materials, you can wrap each rhizome individually in several layers of dry newspaper.
Avoid using garden soil or potting mix for storage. These materials are often too heavy and may contain pathogens that can cause rot during the long winter months.
Packing Your Cannas for the Winter
Once your rhizomes are cured and your storage medium is ready, it is time to pack them away. Choose a container that allows for some airflow. Cardboard boxes, wooden crates, or plastic bins with holes drilled in the sides are all great options.
Start by placing a 2-inch layer of your chosen medium (like peat moss) at the bottom of the container. Place a layer of rhizomes on top of the moss, making sure they do not touch each other. If one rhizome happens to rot, the space between them prevents the rot from spreading to its neighbors.
Cover the first layer with more peat moss until the rhizomes are completely hidden. You can continue layering in this fashion until the box is nearly full. Finish with a final layer of moss on top. If you are using newspaper, wrap each piece snugly and tuck them into the box like eggs in a carton.
Do not put a tight-fitting lid on the container. Instead, cover it loosely with a piece of burlap or a sheet of newspaper. This allows the plants to "breathe" while keeping out light and protecting them from sudden temperature swings.
Steps for Packing
- Choose a breathable box: Use cardboard or a vented plastic bin.
- Add a base layer: Put down 2 inches of peat moss or vermiculite.
- Space the rhizomes: Lay them out so they aren't touching.
- Cover and repeat: Add more medium until the box is full.
- Cover loosely: Avoid airtight lids to prevent mold.
Finding the Perfect Storage Location
The location where you store your boxes is just as important as how you pack them. The ideal environment for a dormant canna is cool, dark, and dry.
The temperature should ideally stay between 40°F and 50°F. If the area is too warm (above 55°F), the rhizomes may think it is spring and try to start growing in the dark. This uses up their stored energy and results in weak, spindly sprouts. If the area is too cold (below 35°F), the rhizomes are at risk of freezing.
Common successful storage spots include:
- Unheated Basements: Usually provide the most consistent cool temperatures.
- Root Cellars: The traditional choice for storing tubers and rhizomes.
- Attached Garages: Can work well, but you must ensure the box is kept away from exterior walls where it might freeze.
- Crawl Spaces: Often provide the right mix of darkness and cool air.
Check the area periodically throughout the winter with a thermometer to make sure the temperature is remaining stable.
Monitoring Your Rhizomes Through Winter
Winterizing isn't a "set it and forget it" task. To ensure the highest survival rate, you should check on your stored cannas at least once a month. This small effort can save your entire collection if something goes wrong.
When you open the box, look for two things: rot and desiccation. Rot will appear as fuzzy mold or soft, slimy spots. If you find a rhizome starting to rot, remove it immediately and throw it away. If the rot is only on a small tip, you can try cutting it off and letting the healthy part dry out before putting it back.
Desiccation is the opposite problem. If the rhizomes look extremely wrinkled or feel light and "corky," they are drying out too much. To fix this, use a spray bottle to lightly mist the storage medium with water. You don't want it to be wet—just slightly damp to the touch. This provides enough humidity to stop the drying process.
Most experienced gardeners are happy if 80% to 90% of their rhizomes survive the winter. Don't be discouraged if you lose one or two. By checking them monthly, you increase the odds that the rest will remain healthy and ready for spring.
Winterizing Cannas in Containers
If you grow your canna lilies in large pots or decorative planters, you have an even easier option for winter storage. You don't necessarily have to dig the rhizomes out of the potting soil. For a step-by-step look at container planting, see How to Plant Canna Lily Bulbs in Pots.
Once the frost has hit and you have cut back the foliage, simply move the entire pot into a cool, frost-free area like a basement or garage. Stop watering the pot completely. The soil will dry out, and the rhizomes will go dormant right where they are.
The benefit of this method is that the soil acts as a natural insulator, protecting the rhizomes from temperature changes. In the spring, you can bring the pot back out, refresh the top few inches of soil, and start watering again. However, keep in mind that cannas are fast growers. After a year or two, they will become "root-bound" and will need to be removed from the pot, divided, and replanted with fresh soil to continue blooming well.
Bringing Cannas Out of Storage
When the days begin to lengthen and the threat of a hard freeze has passed, it is time to think about the upcoming season. Most gardeners start checking their stored rhizomes in late March or April.
You can give your cannas a head start by potting them up indoors about 4 to 6 weeks before the last expected frost date. This "waking up" process involves placing the rhizomes in pots with damp potting soil and moving them to a warm, sunny window. By the time the weather is warm enough to plant them outside, you will already have several inches of green growth.
If you prefer to plant them directly into the garden, wait until the soil has warmed to at least 60°F. Canna lilies are heat-lovers. If they are placed in cold, wet spring soil too early, they will sit idle and may even rot. Patience is rewarded with much faster growth once the summer heat arrives.
Common Myths About Winterizing Cannas
There are many "internet hacks" for storing bulbs, but many of them can actually do more harm than good. Let's clear up a few common misconceptions.
One common myth is that you must wash the rhizomes with bleach or fungicide before storing. For most home gardeners, this is unnecessary and can be hazardous if not handled correctly. As long as your rhizomes are clean, dry, and cured, their natural defenses are usually enough to get them through the winter.
Another myth is that you can store cannas in a kitchen refrigerator. While the temperature is usually safe, refrigerators are designed to remove moisture from the air. This dry environment will often cause rhizomes to shrivel up within a few weeks. Additionally, some fruits release ethylene gas which can interfere with the plant's dormancy. It is much better to use a basement or garage.
Finally, some people believe you should leave the soil on the rhizomes to "keep them natural." While this works for the container method mentioned earlier, leaving clumps of garden soil on bare rhizomes in a box often leads to mold. Cleaning them is a much more reliable way to ensure they stay healthy.
Regional Variations for Winter Care
While the general rules for winterizing apply to most of the US, your specific location may require minor adjustments. Gardening is always a conversation between the plant and your local microclimate.
In the Pacific Northwest, the winters are often wet but not extremely cold. The biggest threat there is rot from the constant rain rather than freezing. If you live in this region, ensuring your storage area is very dry is the top priority.
In the high plains or mountainous regions, the air can be incredibly dry. Gardeners in these areas often find that they need to mist their storage medium more frequently to prevent the rhizomes from turning into "mummies."
In the South (Zone 7 and 8), you might choose to leave your cannas in the ground. If you do this, we suggest cutting the stalks to the ground and covering the area with 6 to 8 inches of shredded leaves or straw. This extra blanket of insulation can make the difference during an unexpected cold snap.
Final Steps for Success
Winterizing is the final act of the gardening season, and it brings a great sense of satisfaction. Knowing that your favorite plants are tucked away safely for the winter allows you to relax and start planning next year's layout.
As you finish packing your boxes, don't forget to label them. If you have different varieties — some tall, some short, some with bronze leaves — it is impossible to tell them apart once they are just bare rhizomes. Use a permanent marker to write the variety name on the box or on a small plastic tag tucked inside.
At Longfield Gardens, we believe that gardening should be a rewarding and stress-free experience. Saving your canna lilies is a great way to build a more beautiful garden year after year. It is a simple, sustainable practice that connects you more deeply to the rhythm of the seasons.
Next Steps:
- Label your storage containers by variety and height.
- Set a monthly reminder on your phone to check for rot or dryness.
- Start browsing new varieties to complement your saved collection next spring.
- Clean and oil your garden tools before putting them away for the season.
Conclusion
Winterizing canna lily bulbs is a simple process that ensures your summer garden returns with even more vigor each year. By waiting for the first frost, lifting the rhizomes with care, and providing a cool, dark home for the winter, you are giving these tropical plants exactly what they need to thrive. Whether you use peat moss in a cardboard box or simply move your pots into a garage, the effort is well worth the beautiful blooms that will greet you next July. We at Longfield Gardens are here to support your journey in creating a more beautiful landscape, one season at a time.
FAQ
Can I store canna lilies in plastic bags?
You can use plastic bags, but they must have several large air holes punched in the sides. Without ventilation, moisture will build up inside the bag and cause the rhizomes to rot very quickly. Most gardeners find that cardboard boxes or paper bags are safer because they naturally "breathe."
What happens if I forget to dig up my cannas before the ground freezes?
If only the top inch of soil has frozen, your rhizomes may still be fine. However, if the freeze has gone down several inches, the water inside the fleshy rhizomes may have frozen, which destroys the plant tissue. Dig them up as soon as possible and check for mushy spots; if they are firm, they might still be salvageable.
Do I need to water the rhizomes during the winter?
You should not "water" them in the traditional sense. You want them to stay dormant, not grow. However, if you check them and find they look very shriveled and dry, you should lightly mist the storage medium (like the peat moss) with a spray bottle to add a tiny bit of humidity.
Why did my stored canna rhizomes turn soft and mushy?
This is usually caused by one of three things: the rhizomes were not cured (dried) long enough before storage, the storage area was too damp/humid, or there was no airflow in the container. To prevent this, ensure the skin feels dry before packing and use a breathable container like a cardboard box.