Introduction
There is nothing quite like the tropical flair that cannas bring to a summer landscape. With their oversized, banana-like leaves and vibrant, torch-like flowers, they turn any backyard into a lush retreat. At Longfield Gardens, we love how these fast-growing plants provide an architectural punch that lasts from midsummer right up until the first frost. Watching a small rhizome transform into a six-foot-tall masterpiece in a single season is one of the most rewarding experiences a gardener can have.
Whether you need to dig up your canna "bulbs" (which are technically called rhizomes) depends almost entirely on where you live. For gardeners in warmer climates, these plants are reliable perennials that stay in the ground year-round. However, in cooler regions, a little bit of fall preparation ensures your favorite varieties return even bigger and better the following year. This guide will help you determine the best winter plan for your cannas based on your local climate and garden goals.
The decision to lift your cannas is a simple choice between treating them as annuals or preserving them as long-term garden investments.
Understanding Your USDA Hardiness Zone
The most important factor in deciding whether to dig up your canna rhizomes is your USDA hardiness zone. These zones are based on the average minimum winter temperature in your area. Because cannas are native to tropical and subtropical regions of Central and South America, they have a limited tolerance for freezing soil.
In zones 8 through 11, cannas are generally considered winter-hardy. In these warmer regions, the ground does not freeze deep enough to damage the rhizomes. You can simply leave them in the place where they grew, and they will sprout again when the soil warms up in the spring. Some gardeners in zone 7 find success leaving cannas in the ground if they provide a very thick layer of mulch, though digging them up is a safer bet for guaranteed results.
If you live in zones 3 through 6, the winter frost will penetrate deep into the soil. If left outdoors, the fleshy rhizomes will freeze and turn to mush. For gardeners in these northern areas, you have two choices: you can treat them as annuals and buy fresh rhizomes each spring, or you can lift and store them. Lifting them is a wonderful way to save money and keep a particularly beautiful variety in your collection for years to come.
Key Takeaway
- Zones 8-11: Leave them in the ground.
- Zone 7: Lift them or apply heavy mulch for protection.
- Zones 3-6: Dig them up and store them indoors for the winter.
When Is the Right Time to Dig?
Timing is everything when it comes to lifting cannas. You want to give the plants as much time as possible to store energy in their rhizomes, but you must act before the ground freezes solid. The best indicator for when to start is the weather itself.
Wait for the first light frost of the season. You will notice that the lush green or bronze foliage turns black or brown almost overnight after a frost. This might look like a sad moment, but it is actually a helpful signal. The frost tells the plant to stop growing and move into a dormant state. Once the foliage has been "zapped" by the cold, the energy from the leaves moves down into the rhizome to prepare for winter.
If you live in an area where frost comes very late, you can still dig them up in late autumn once the temperatures consistently stay in the 40s. It is much easier to work with the plants when the soil is still relatively dry and workable. Avoid waiting until the ground is frozen hard, as this makes digging difficult and can damage the sensitive "eyes" or growing points on the rhizomes.
How to Dig Up Canna Rhizomes Step-by-Step
Lifting cannas is a straightforward process that only takes a few minutes per clump. Because canna rhizomes grow outward and can become quite large over a single summer, it helps to have a sturdy garden fork or spade ready.
1. Cut Back the Foliage
Before you start digging, use a pair of garden shears or a sharp knife to cut the stalks down. Leave about two to four inches of stem attached to the rhizome. This small "handle" makes the rhizomes easier to move and helps you identify which side is up when it comes time to replant in the spring.
2. Loosen the Soil
Start digging about a foot away from the base of the plant. Canna rhizomes spread horizontally, so you want to avoid slicing into them with your shovel. Gently lift the soil all the way around the clump until the entire mass feels loose. Use your garden fork to pry the clump upward from underneath.
3. Remove Excess Dirt
Once the clump is out of the ground, shake it gently to remove large chunks of soil. You do not need to scrub them clean or wash them with a hose. In fact, keeping a little bit of soil attached can sometimes help prevent the rhizomes from drying out too much during storage. If the soil is very wet and muddy, let the clumps sit in a garage or shed for a day to dry slightly before handling them further.
4. Inspect the Rhizomes
Take a moment to look over your harvest. Healthy rhizomes should feel firm and heavy for their size. If you see any soft spots or signs of pests, you can trim those sections away with a clean knife. Large clumps can be broken into smaller pieces now, or you can wait until spring to divide them. Ensure each piece you plan to keep has at least one or two "eyes," which look like small, raised bumps or buds.
What to do next:
- Label your rhizomes immediately using a permanent marker or garden tag.
- Work on a dry day to make soil removal easier.
- Keep different varieties in separate piles to avoid confusion.
- Move the lifted clumps to a frost-free area like a garage or porch for the next step.
Curing and Preparing for Storage
After digging, the rhizomes need a short period of "curing." This process allows the outer skin to toughen up and any remaining moisture on the surface to evaporate. Curing is the best way to prevent rot during the long winter months.
Place your cleaned rhizomes in a single layer on a piece of cardboard or a plastic tray. Keep them in a cool, dry place that is protected from rain and frost. A ventilated garage, basement, or garden shed works perfectly. Let them sit for two to three days. You will notice the cut stems begin to dry out and the outer skin of the rhizome becomes less tacky.
Do not leave them out for too long, especially in very dry air. Unlike some other bulbs, canna rhizomes do not have a hard outer shell, so they can shrivel if they lose too much internal moisture. The goal is a dry surface but a firm, plump interior.
Choosing the Right Storage Container
The way you pack your cannas determines how well they survive until spring. The goal of storage is to keep the rhizomes dormant, cool, and slightly hydrated. If they are too wet, they will rot; if they are too dry, they will shrivel and die.
Many gardeners find success using cardboard boxes, plastic bins with air holes, or even paper grocery bags. Avoid airtight plastic containers, as these trap moisture and almost always lead to mold.
To maintain the perfect moisture balance, use a packing medium. Common choices include:
- Peat moss: Holds a small amount of moisture and is naturally acidic, which can help deter rot.
- Vermiculite or Perlite: Excellent for insulation and moisture control.
- Wood shavings: Often sold as pet bedding, these are inexpensive and provide great airflow.
- Dry potting soil: A simple and effective way to mimic the natural environment of the rhizome.
Layer the packing medium in the bottom of your container, place the rhizomes on top so they aren't touching each other, and then cover them with more of the medium. This "nesting" protects them from temperature fluctuations and prevents any rot from spreading from one rhizome to another.
Finding the Perfect Winter Location
Once your cannas are packed away, you need to find a spot where they can sleep undisturbed. The ideal storage temperature is between 40°F and 50°F. This is cold enough to keep them dormant but warm enough that they won't freeze.
An unheated basement, a crawl space, or a cool closet in a mudroom are usually the best spots. If you store them in a garage, make sure the container is kept off the concrete floor and away from exterior walls where temperatures might drop too low.
It is a good idea to check on your "bulbs" once a month. Open the box and feel a few of the rhizomes. If they feel extremely shriveled, you can lightly mist the packing medium with a spray bottle of water. If you notice any soft or fuzzy spots starting to form, remove the affected rhizome immediately and leave the box open for a day to improve airflow.
Caring for Container-Grown Cannas
If you grow your cannas in pots to decorate a patio or deck, you have a few extra options for winter care. Containers offer a convenient way to manage these plants without ever having to lift a shovel.
One method is to simply move the entire pot into a frost-free area after the first frost hits. Cut the foliage back to the soil line and move the pot into a basement or cool garage. Stop watering entirely. The soil in the pot will act as the storage medium, keeping the rhizomes protected and dormant. In the spring, you can move the pot back outside, start watering again, and the plants will emerge.
Another option for smaller, dwarf varieties is to bring them inside as houseplants. If you have a very sunny window or a sunroom, cannas can continue to grow through the winter. However, they may not bloom as vigorously without the intense heat and light of the summer sun. Most gardeners find that letting the plants go dormant results in a much stronger show the following summer.
Leaving Cannas in the Ground
For those living in zones 8 through 11, the fall routine is much simpler. You do not have to dig up your cannas, but a little bit of maintenance will help them look their best when spring arrives.
Once the foliage begins to yellow or look tattered in late autumn, cut the stalks down to within a few inches of the ground. This keeps the garden looking tidy and prevents old foliage from harboring pests over the winter.
In zone 8, where temperatures can occasionally dip, it is a good idea to apply a three- to four-inch layer of organic mulch over the planting area. Straw, shredded leaves, or wood chips work well. This mulch acts like a warm blanket, protecting the shallow rhizomes from unexpected cold snaps. In the spring, you can pull the mulch back to allow the sun to warm the soil and trigger new growth.
Why Digging Them Up Is Worth the Effort
While it might seem like an extra chore, there are several benefits to digging up your cannas in the fall beyond just keeping them alive.
First, cannas are incredibly prolific. A single rhizome planted in May can turn into a massive clump by October. When you dig them up, you have the opportunity to divide these clumps. By separating the new growth from the old, you can double or triple your plant collection every year for free. These extra rhizomes make wonderful gifts for friends and neighbors.
Second, lifting your cannas allows you to refresh your garden design. You aren't committed to the same layout year after year. You can move your tall, orange-flowered varieties to the back of a different border or try your dwarf yellow varieties in new containers. Gardeners who prefer compact plants can browse Short Cannas, while taller options are collected in Tall Cannas.
Finally, storing rhizomes gives you a "head start" on the next season. In early spring, about four to six weeks before the last frost, you can take your stored rhizomes out and "wake them up" in pots indoors. By the time it is warm enough to plant them outside, you will already have established plants, leading to much earlier blooms.
Key Takeaway
- Lifting cannas is the only way to save them in cold climates.
- It allows you to divide and multiply your plants for free.
- Stored rhizomes can be started early indoors for a longer bloom season.
- It’s a great way to ensure your favorite colors return year after year.
Common Mistakes to Avoid
Gardening is all about learning from experience. When it comes to overwintering cannas, a few small mistakes can lead to lost rhizomes. By knowing what to look for, you can ensure a 100% success rate.
One common error is digging too early. If you lift the plants while they are still in full, lush growth before any cold weather has arrived, the rhizomes may not have stored enough sugars to survive a long dormancy. Always wait for that first sign of cold-induced dormancy.
Another mistake is washing the rhizomes with a high-pressure hose. While it’s tempting to want them perfectly clean, excessive water can get trapped in the nooks and crannies of the rhizome, leading to rot during storage. A gentle shake or a soft brush is all you need to remove excess soil.
Lastly, avoid storing them in a place that is too warm. If you put your canna boxes in a heated part of the house, like a laundry room or near a furnace, the plants may think it is springtime. They might start to sprout pale, weak stems in the dark, which uses up the energy they need for the real growing season. Keep them in the "sweet spot" of 40°F to 50°F for the best results.
Preparing for Spring Replanting
As winter winds down and the days get longer, you can start looking forward to getting your cannas back into the garden. The best time to replant is in late spring, after all danger of frost has passed and the soil has warmed to at least 60°F. A good rule of thumb is to plant them around the same time you would put your tomato plants or peppers in the ground.
Before planting, take your rhizomes out of storage and give them a final inspection. They should still feel firm. If you didn't divide them in the fall, now is the perfect time. Use a sharp, clean knife to cut the rhizomes into pieces, making sure each piece has at least two "eyes." Let the cut ends dry for a day before planting to prevent soil-borne diseases from entering the fresh cuts.
Our team at Longfield Gardens recommends planting the rhizomes about four inches deep. If you are planting them in a garden bed, space them about one to two feet apart to give them plenty of room to grow. If you are using containers, one large rhizome per 12-inch pot is usually sufficient. With plenty of sun, water, and a bit of fertilizer, your cannas will quickly return to their former glory, providing that spectacular tropical look all over again. For additional Canna Planting and Care guidance, review the growing requirements before planting.
Conclusion
Taking care of your cannas in the fall is a simple way to preserve the beauty and investment of your summer garden. Whether you live in a climate where they can stay in the ground or you need to lift and store them, these plants are remarkably resilient. By following these basic steps for digging, curing, and storing, you ensure that your landscape remains a vibrant, tropical paradise year after year.
- Check your USDA zone to determine if lifting is necessary.
- Wait for the first frost to signal dormancy before digging.
- Store rhizomes in a cool, dry place in a breathable medium.
- Check monthly for moisture levels and signs of rot.
At Longfield Gardens, we believe that gardening should be a joyful and accessible experience for everyone. Saving your cannas is a rewarding ritual that connects you to the seasons and prepares you for the excitement of next year's blooms. With just a little bit of effort this fall, you'll be well on your way to another season of spectacular, head-turning color.
Overwintering cannas is one of the easiest ways to grow your garden for free. By protecting these tropical treasures from the winter cold, you ensure they return even more vigorous and beautiful each spring.
FAQ
Can I leave cannas in the ground in Zone 7?
In Zone 7, leaving cannas in the ground is a bit of a gamble but often successful with extra protection. If you choose to leave them, cut the stalks to the ground and apply a thick, six-inch layer of mulch like straw or bark over the site. This insulation helps keep the soil temperature from dropping low enough to freeze the rhizomes.
What happens if I don't dig up my cannas in a cold climate?
If you live in a region with freezing winters (Zones 3-6) and leave your cannas in the ground, the water inside the fleshy rhizomes will freeze. This causes the cells to rupture, and when the ground thaws, the rhizomes will turn into a soft, rotten mass. They will not grow back in the spring, and you will need to purchase new ones. For broader guidance, see Longfield Gardens’ winter storage instructions for tender bulbs and tubers.
Do I need to water canna rhizomes while they are in storage?
You should not "water" them in the traditional sense, as this will cause rot. However, you should check them once a month to ensure they haven't become bone-dry. If the rhizomes feel shriveled and light, lightly mist the packing medium (like peat moss or wood shavings) with a spray bottle to provide just a hint of humidity.
Should I wash the dirt off canna bulbs before storing them?
It is best to avoid washing canna rhizomes with water before storage. Excess moisture is the primary cause of rot during the winter. Instead, let the clumps dry for a day in a protected area and then gently brush off the loose soil with your hands or a soft brush before packing them away. For more detailed instructions, read How to Dig Up and Store Canna Bulbs.
