Table of Contents
- Introduction
- Understanding Your Planting Zone
- The Importance of Timing
- Preparing to Dig Your Cannas
- Cleaning and Inspecting the Rhizomes
- The Curing Phase: A Critical Step
- Selecting a Storage Container and Medium
- Finding the Perfect Winter Location
- Storing Cannas Grown in Containers
- Checking on Your Bulbs During Winter
- Dividing Cannas for More Blooms
- Moving Back Outdoors in Spring
- Why We Love Overwintering Cannas
- Conclusion
- FAQ
Introduction
There is nothing quite like the tropical flair that cannas bring to a summer garden. Their oversized, paddle-shaped leaves and neon-bright blooms create a lush, vacation-like atmosphere in even the most standard backyard. At Longfield Gardens, we love how these vigorous plants stand up to the mid-summer heat when other flowers might begin to fade. As the season winds down and the first crisp nights of autumn arrive, many gardeners wonder how to keep that tropical magic alive for next year.
The question of whether you have to dig up your canna bulbs depends almost entirely on where you live and how you choose to garden. In warmer climates, these plants are happy to stay in the ground year-round, while in cooler regions, they need a little extra help to survive the winter. This guide is for anyone who wants to ensure their cannas return bigger and better every summer. We will walk through the specific climate zones that require digging and provide a simple, step-by-step process for storing your plants safely.
Ultimately, overwintering tropical and subtropical plants like cannas is a rewarding part of the gardening cycle that saves you money and allows your plants to grow more impressively each season. Whether you are a beginner or a seasoned pro, the process is straightforward and highly effective.
Understanding Your Planting Zone
The very first step in deciding if you need to dig up your cannas is identifying your USDA hardiness zone. Cannas are tropical and subtropical plants by nature, which means they are sensitive to freezing temperatures. While the foliage will die back when hit by frost, the health of the underground rhizome—often called a bulb—is what determines if the plant will grow back.
If you live in USDA zones 8 through 11, you generally do not need to dig up your canna bulbs. In these southern and coastal regions, the ground rarely freezes deep enough to damage the rhizomes. You can simply cut the foliage back to the ground after it turns brown and leave the roots in place. Many gardeners in these areas choose to add a light layer of mulch just to keep the soil moisture consistent, but the plants are essentially self-sufficient through the winter months.
For gardeners in zone 7, the decision is a bit of a "choose your own adventure" scenario. In a typical year, cannas in zone 7 will survive underground if they are protected with a thick layer of mulch, such as six inches of straw or shredded leaves. However, if a record-breaking cold snap occurs, those bulbs could be at risk. Many people in zone 7 choose to dig them up just to be safe, while others rely on the insulation of the soil.
If you are in zone 6 or colder, digging up your canna bulbs is a necessity if you want to see them again next year. In these northern climates, the frost penetrates deep into the earth. If the rhizome freezes, it turns to mush and will not sprout in the spring. By bringing them indoors, you are essentially giving them a cozy place to nap until the sun returns.
Key Takeaway
- Zones 8-11: Leave them in the ground.
- Zone 7: Mulch heavily or dig for extra safety.
- Zones 6 and colder: Dig and store indoors to prevent freezing.
The Importance of Timing
Timing is everything when it comes to overwintering tropical plants. You want to give your cannas as much time as possible to store energy in their rhizomes. Throughout the summer, the leaves act like solar panels, soaking up the sun and sending sugars down to the roots. The more energy they store, the more spectacular the flowers will be next year.
The best time to dig up your cannas is right after the first "blackening" frost. This is a light frost that kills the leaves and turns them a dark brown or black color, but doesn't yet freeze the ground. This frost serves as a natural alarm clock for the plant, telling it that the growing season is officially over and it is time to go dormant.
If you live in an area where the ground freezes solid very quickly, keep a close eye on the weather forecast. You want to get the bulbs out of the dirt before the soil itself becomes a block of ice. Digging in frozen soil is difficult for you and can be physically damaging to the plant's delicate structures.
Preparing to Dig Your Cannas
Once the foliage has been nipped by frost, you can begin the transition process. Start by cutting the stalks down. Use a sharp pair of garden shears to prune the stems so that only about two to four inches of the stalk remains above the soil line. This "handle" makes it much easier to see where the plant is and gives you something to hold onto without putting stress on the roots.
Before you grab your shovel, make sure you have a clear workspace. A wheelbarrow, a garden tarp, or a large potting bench are all great places to set the clumps once they are out of the ground. This keeps the mess contained and allows you to inspect the rhizomes easily.
Choosing the Right Tools
You don't need fancy equipment to dig cannas, but the right tool makes the job easier. A sturdy garden fork is often preferred over a traditional shovel. A fork allows you to lift the soil and the roots while letting some of the loose dirt fall through the tines. If you only have a shovel, that works too; just be sure to give the plant a wide berth so you don't accidentally slice through the center of a healthy rhizome.
The Lifting Process
When you are ready to lift, move in a circle around the plant. Insert your fork or shovel about 8 to 12 inches away from the main stem. Push the tool straight down and gently pry upward. By working your way around the entire perimeter, you gradually loosen the root ball from the surrounding soil.
Once the clump feels loose, reach under the center of the mass with your tool and lift the whole thing out. Don't be surprised if the clump is much larger than what you planted in the spring! Cannas are famous for multiplying underground. A single rhizome planted in May can easily turn into a heavy mass of five or ten interconnected "tubers" by October.
What to Do Next
- Cut stalks down to 3 inches.
- Identify the perimeter of the root system.
- Use a garden fork to lift the entire clump gently.
- Place the clumps on a tarp or in a wheelbarrow for cleaning.
Cleaning and Inspecting the Rhizomes
With the cannas out of the ground, the next step is removing the excess soil. You can do this by hand, gently shaking the clump to dislodge loose dirt. Some gardeners prefer to use a garden hose to rinse the rhizomes clean. Rinsing makes it much easier to see the "eyes" (the small bumps where next year's growth will come from) and to spot any signs of damage.
If you choose to wash your cannas, make sure they have plenty of time to dry afterward. Excess moisture is the primary enemy of stored bulbs, as it can lead to mold or rot. A quick rinse is fine, but avoid soaking them for long periods.
While you are cleaning, take a moment to inspect the health of the plant. Look for any soft spots, discoloration, or signs of pests. A healthy canna rhizome should feel firm, much like a fresh potato. If you find any parts that feel mushy or look diseased, use a clean knife to trim those sections away. This prevents the rot from spreading to the healthy parts of the plant during the long winter months.
The Curing Phase: A Critical Step
One of the most common mistakes gardeners make is putting their canna bulbs directly into storage while they are still wet or "green." To ensure they stay healthy all winter, you must allow them to "cure." Curing is simply the process of letting the outer skin of the rhizome dry out and toughen up.
Find a cool, dry, and well-ventilated spot to lay out your cannas. A garage, a shed, or a covered porch works perfectly, provided the temperature stays above freezing. Spread the rhizomes out in a single layer so they aren't touching each other. This allows air to circulate around every surface.
Most cannas need about three to seven days to cure properly. During this time, the cut ends of the stalks will dry up, and the outer skin of the rhizome will become slightly papery. This protective layer acts as a barrier against dehydration and disease while the plant is dormant.
Selecting a Storage Container and Medium
Once your cannas are cured, it is time to pack them away for their winter nap. The goal of storage is to keep the bulbs cool enough to stay dormant but protected enough that they don't freeze or completely dry out.
Containers
Cardboard boxes, plastic bins with air holes, and paper bags are all excellent choices. Avoid using airtight plastic containers or sealed bags. Without airflow, the natural respiration of the plant can cause moisture to build up, which leads to rot. If you use a plastic tote, simply drill a few small holes in the sides to allow the bulbs to breathe.
Storage Media
To keep the rhizomes from shriveling up, it is helpful to pack them in a "medium" that regulates moisture. Some popular options include:
- Peat Moss: This is a classic choice because it holds just a tiny bit of moisture while remaining airy.
- Vermiculite: A lightweight mineral that is excellent at preventing rot.
- Pine Shavings: Often sold as animal bedding, these are inexpensive and provide great insulation.
- Newspaper: You can also wrap individual rhizomes in sheets of dry newspaper.
Place a layer of your chosen medium at the bottom of the container, then nestle the cannas inside. Try to keep them from touching one another; if one bulb develops an issue, the medium will act as a buffer to keep it from spreading to its neighbors. Cover the bulbs with another layer of the medium until they are tucked in completely.
Finding the Perfect Winter Location
Where you store your boxes is just as important as how you pack them. The ideal temperature for storing canna bulbs is between 40°F and 55°F.
A cool basement, a crawl space, or a root cellar is usually the best spot. An attached garage can also work, but be cautious. In very cold climates, garages can sometimes drop below freezing, which would be fatal for the cannas. Conversely, don't store them in a heated living area or near a furnace. If the temperature stays too warm, the plants might think it is spring and try to start growing in the dark, or they may simply dry out and die.
What to Do Next
- Choose a breathable container (cardboard or vented plastic).
- Layer the bulbs in peat moss, shavings, or newspaper.
- Ensure bulbs are not touching each other.
- Move the container to a cool (40–55°F), dark location.
Storing Cannas Grown in Containers
If you grow container-friendly cannas in pots, you have a major advantage when winter arrives. You don't necessarily have to dig them out of the soil at all. For many gardeners, the easiest way to overwinter potted cannas is to let the frost kill the foliage, cut the stalks back to the soil line, and then move the entire pot into a cool, frost-free area like a basement.
The soil in the pot acts as a natural storage medium, protecting the rhizomes from drying out. If you choose this method, stop watering the pot entirely. You want the soil to be dry so the plant stays in a deep sleep. In the spring, you can bring the pot back out into the sun, start watering, and watch the new shoots emerge.
Eventually, even container-grown cannas will need to be divided. They grow so vigorously that they will eventually become "root-bound," meaning the roots have filled all the available space. Every two or three years, it is a good idea to tip the pot over, shake out the soil, and divide the large mass of rhizomes into smaller pieces before replanting them.
Checking on Your Bulbs During Winter
Overwintering isn't a "set it and forget it" task. It is a good idea to check on your stored cannas about once a month. This only takes a few minutes but can save your entire collection.
Open the boxes and look for any signs of trouble. If you see a rhizome that is turning soft or showing fuzzy mold, remove it immediately. If the rest of the bulbs feel very light and look wrinkled or shriveled, they might be getting too dry. You can use a spray bottle to lightly mist the storage medium (not the bulbs directly) with a tiny bit of water. You don't want the medium to be wet—just "not bone dry."
Most of the time, you won't need to do anything at all. But a quick monthly check ensures that small problems don't become big ones.
Dividing Cannas for More Blooms
One of the most exciting things about cannas is that they are the gift that keeps on giving. Because they multiply so quickly, you will likely have many more plants in the fall than you started with in the spring. You can divide these rhizomes either in the fall before you store them or in the spring before you replant them.
To divide a canna, look for the natural "joints" in the rhizome mass. Each piece you cut should have at least one or two "eyes" (the small pointed buds). Use a sharp, clean knife to make the cuts. If you divide them in the fall, let the cut surfaces dry for an extra day before packing them away. If you wait until spring, you can plant the pieces directly into the ground or into pots once the weather warms up.
Sharing extra canna divisions with neighbors and friends is a wonderful way to spread the joy of gardening. Since cannas are so easy to grow, they make great gifts for new gardeners.
Moving Back Outdoors in Spring
When the days begin to lengthen and the threat of frost has passed, it’s time to wake up your cannas. This usually happens in late spring, around the same time you would plant tomatoes or other warm-weather vegetables.
Wait until the soil has warmed up to at least 60°F. If the soil is too cold and wet, the rhizomes might sit and rot rather than grow. If you want a head start, you can plant your stored cannas in pots indoors about four to six weeks before the last frost date. Place them in a sunny window, and by the time the weather is nice enough to go outside, you will already have several inches of green growth.
When planting, place the rhizomes about 4 to 6 inches deep with the "eyes" or points facing upward. Space them about one to two feet apart, depending on the variety. Taller varieties need a bit more elbow room to show off their spectacular foliage.
Why We Love Overwintering Cannas
At Longfield Gardens, we believe that gardening should be a rewarding and accessible hobby. While "digging up bulbs" might sound like a lot of work at first, most gardeners find that the process takes less than an hour for a typical backyard collection. When you consider the beauty and height these plants provide, that hour of effort is one of the best investments you can make in your landscape.
By learning to overwinter your cannas, you become a more connected and capable gardener. You learn the rhythms of the seasons and the specific needs of your plants. There is a special kind of satisfaction that comes from seeing a tiny sprout emerge from a rhizome you personally cared for all winter.
Cannas are resilient, vibrant, and incredibly forgiving. They don't ask for much—just some sun, some water, and a frost-free place to sleep in the winter. If you give them those few basics, they will reward you with a tropical paradise year after year.
Key Takeaway Overwintering cannas is a simple cycle: wait for the frost, dig carefully, cure the skin, and store in a cool, dry place. This small amount of effort ensures your garden stays vibrant without the need to buy new plants every spring.
Conclusion
Deciding whether you have to dig up your canna bulbs is a simple matter of knowing your local climate and how much risk you are willing to take. For most gardeners in the northern half of the country, a quick autumn harvest is the secret to keeping these tropical beauties for a lifetime. The process of digging, curing, and storing is a peaceful way to wrap up the gardening season and prepare for the excitement of next year.
At Longfield Gardens, we are here to support you in every step of your gardening journey. From choosing the perfect varieties to providing the practical tips you need to help them thrive, our goal is to help you create a yard you love. Gardening is all about the joy of growth, and cannas are some of the most joyful plants you can grow.
- Check your USDA zone to see if digging is required.
- Wait for the first light frost before you begin.
- Allow the rhizomes to cure before packing them away.
- Store in a cool, dark place and check periodically.
Successful gardening isn't about following a set of strict, scary rules; it's about understanding what your plants need and providing it in a way that fits your life. Protecting your cannas for the winter is a simple act of care that pays off in spectacular summer blooms.
FAQ
Can I leave cannas in the ground if I live in Zone 7?
In Zone 7, cannas can often survive the winter if you apply a very thick layer of mulch, such as six to eight inches of straw or leaves. However, this is not a guarantee, as an unusually cold winter or poorly draining soil can still cause the bulbs to rot or freeze. If you have a particularly prized variety, digging it up is the safest way to ensure its survival.
Do I have to wait for a frost to dig them up?
While it is not strictly required to wait for a frost, it is highly recommended because the frost signals the plant to move into dormancy. If you must dig them earlier due to travel or scheduling, try to wait until the foliage begins to yellow naturally. This ensures the rhizome has stored enough energy to last through the winter and bloom again in the spring.
What happens if I don't wash the dirt off the bulbs?
You do not have to wash the bulbs, and many gardeners simply shake off the loose soil and call it a day. The main benefit of washing is that it allows you to see the health of the rhizome more clearly and prevents soil-borne pests from coming into your storage area. If you don't wash them, just make sure they are extra dry before you pack them away to prevent mold.
My stored cannas look shriveled; are they dead?
A little bit of wrinkling is normal as the rhizomes lose a small amount of moisture during dormancy. As long as the rhizome still feels firm and not "squishy" or hollow, it is likely still alive. If they look very dehydrated, you can mist your storage medium with a little water, but usually, they will plump right back up once they are planted and watered in the spring.