Table of Contents
- Introduction
- Understanding the Canna Lily Life Cycle
- When Is the Right Time to Dig?
- Step-by-Step: Digging and Cleaning Your Rhizomes
- The Importance of Curing Before Storage
- Selecting Your Storage Containers and Media
- Ideal Winter Storage Conditions
- Overwintering Cannas in Containers
- Checking Your Cannas During the Winter
- Preparing for Spring Replanting
- Conclusion
- FAQ
Introduction
There is nothing quite like the bold, tropical energy that the canna lilies bring to a summer garden. Their oversized leaves and vibrant, torch-like blooms make them the stars of the show from mid-summer until the first hint of autumn. At Longfield Gardens, we believe that the joy of growing these stunning plants shouldn't have to end when the temperature drops. Saving your canna lilies for next year is a rewarding way to build a bigger, more beautiful garden every season without starting from scratch.
Learning how to winter over canna lily bulbs is one of the most practical skills a home gardener can master. While these plants are tropical by nature, they are incredibly resilient if you give them a little help during the cold months. This process involves a few simple steps: timing your harvest, cleaning and curing the roots, and finding a cozy, dark spot for them to rest. Whether you are a beginner or have been gardening for years, this guide will help you keep your plants healthy and ready for a spectacular spring comeback.
In this article, we will cover the best techniques for digging, storing, and monitoring your canna rhizomes through the winter. We will also look at how to handle container-grown plants and how to tell when your cannas are ready to go back into the ground. By following these straightforward steps, you can ensure your favorite varieties return year after year.
Understanding the Canna Lily Life Cycle
To store cannas successfully, it helps to understand how they grow. Although most people call them "bulbs," cannas actually grow from rhizomes. A rhizome is a thick, fleshy underground stem that stores energy for the plant. During the summer, the rhizome uses that energy to push up tall stalks and broad leaves. As the season progresses, the plant stores new energy back down into the rhizome to prepare for the next year.
In warm climates, specifically USDA hardiness zones 8 through 10, canna lilies can stay in the ground all year. The soil stays warm enough that the rhizomes don’t freeze, allowing them to go dormant and then sprout again when spring arrives. However, for those of us in zone 7 or colder, the frozen winter soil can damage these tropical structures.
Wintering over is simply the process of mimicking the plant's natural dormant period in a controlled environment. By lifting the rhizomes out of the cold soil and keeping them in a cool, dry place, you protect that stored energy. When you plant them back out in the spring, they have a "head start" compared to newly purchased plants, often resulting in larger displays and earlier blooms.
When Is the Right Time to Dig?
Timing is everything when it comes to a successful winter harvest. If you dig too early, the plant may not have finished storing all the energy it needs for the following year. If you wait too long, a deep freeze might reach the rhizomes and cause them to turn mushy.
The best signal comes from nature itself. We recommend waiting until the first light frost hits your area. You will notice the lush green or bronze foliage suddenly turns brown or black. While it might look a little sad, this is actually a positive sign. The frost tells the plant that the growing season is over and it is time to move into dormancy.
Once the foliage has been "zapped" by frost, you generally have a window of a few days to a couple of weeks to get them out of the ground. Ideally, you want to dig them up before the ground itself freezes hard. If you live in a region where the first frost is followed immediately by a deep, ground-penetrating freeze, keep a close eye on the weather forecast and aim for that sweet spot just after the first light frost.
Key Takeaway: Wait for the first light frost to turn the leaves brown before digging. This ensures the plant has stored maximum energy for its winter nap.
Step-by-Step: Digging and Cleaning Your Rhizomes
Digging up canna lilies is a straightforward process, but it requires a gentle hand to avoid bruising the fleshy rhizomes. Unlike hardy rocks or roots, these storage organs can be sensitive to sharp impacts.
Cutting the Stalks
Before you reach for your shovel, start by trimming the plant back. Use a pair of sharp, clean garden shears or loppers to cut the stalks down to about 4 to 6 inches above the soil line. Leaving this "stub" or "handle" makes the rhizomes much easier to manage as you move them around. It also helps you keep track of which end is up when you eventually replant.
Lifting the Clumps
Cannas are vigorous growers, and their root systems can spread quite wide over a single summer. To avoid slicing through the rhizomes, start your digging about 12 inches away from the base of the stalks.
- Use a garden fork or a sturdy shovel to loosen the soil all the way around the clump.
- Gently pry upward, lifting the entire mass of soil and rhizomes out of the ground.
- If the clump is too large to lift at once, you can carefully divide it into smaller sections with your shovel, but try to keep the main rhizome pieces intact.
Cleaning the Soil
Once the clump is out of the ground, shake it gently to remove the bulk of the loose soil. You can use your hands to brush away more dirt, but avoid the urge to scrub them vigorously. Some gardeners like to use a garden hose to wash the rhizomes clean. This is fine, but it adds extra moisture that must be dried off later. If your soil is relatively dry, simply brushing off the excess is often the safer, simpler choice.
What to do next:
- Identify your "frost date" to prepare your tools.
- Check your garden shears for sharpness and clean them with rubbing alcohol.
- Prepare a space in a garage or shed where the rhizomes can dry out for a few days.
The Importance of Curing Before Storage
Curing is perhaps the most skipped step in wintering over bulbs, yet it is one of the most important. Curing simply means letting the rhizomes air-dry for a short period before they go into long-term storage. This process allows the "skin" of the rhizome to toughen up and any small nicks or cuts from the digging process to callus over.
After you have cleaned off the majority of the soil, find a dry, well-ventilated spot that is protected from frost and direct sunlight. A garage workbench, a garden shed, or even a covered porch works well. Spread the rhizomes out in a single layer on top of old newspapers or cardboard.
Leave them to dry for about 3 to 7 days. You are looking for the exterior to feel dry to the touch and any remaining bits of soil to become crumbly. If you washed your rhizomes with a hose, they may need the full week to ensure no moisture is trapped in the crevices. Proper curing is the best way to prevent rot and mold from developing while the plants are tucked away for the winter.
Selecting Your Storage Containers and Media
Once your cannas are cured, they need a home for the winter. The goal is to keep them in an environment that is "just right"—not so wet that they rot, but not so dry that they shrivel up like raisins.
The Container
Cardboard boxes, wooden crates, or plastic bins without lids are excellent choices. We recommend avoiding sealed plastic bags or airtight containers. Rhizomes are living things; they "breathe" slightly even while dormant. If you seal them up, moisture can build up inside, leading to the dreaded "black mush" that ruins a winter harvest. If you use a plastic bin, leave the lid off or drill several large holes in the sides to ensure airflow.
The Storage Medium
To maintain the perfect moisture balance, you should pack the rhizomes in a loose material. This material acts as insulation and a moisture regulator. Common choices include:
- Peat Moss: This is a classic choice because it holds a tiny bit of moisture but stays fluffy and airy.
- Wood Shavings: Often sold as pet bedding, these provide great airflow and are very affordable.
- Vermiculite or Perlite: These sterile minerals are excellent for moisture control.
- Newspaper: If you don't have other materials, wrapping individual rhizomes in several layers of newspaper can also work.
Place a layer of your chosen material in the bottom of the container, then nestle the rhizomes on top. Cover them with more material so they aren't touching each other. This "social distancing" for plants ensures that if one rhizome happens to develop a spot of rot, it won't easily spread to its neighbors.
Ideal Winter Storage Conditions
Where you put your storage boxes is just as important as how you pack them. Cannas need a spot that mimics a deep, quiet sleep.
Temperature
The ideal temperature range for storing canna lily rhizomes is between 40°F and 55°F. This is cool enough to keep the plant dormant but warm enough to prevent the cells from freezing and bursting. A cool basement, a crawl space, or a root cellar are usually perfect. An attached garage can work, provided it stays above freezing all winter long. Avoid spots near heaters, furnaces, or dryer vents, as the warmth will either wake the plants up too early or dry them out completely.
Light
Keep your cannas in total darkness. Light is a signal for plants to grow. If they are stored in a bright area, they may try to send up pale, weak sprouts in the middle of January. Darkness helps keep the rhizomes in a state of deep rest until you are ready for them in the spring.
Humidity
A moderately humid environment is best. If your storage area is extremely dry (like a heated basement), you may find that the rhizomes start to feel light and shriveled by mid-winter. If this happens, you can lightly mist the packing material with a spray bottle once a month. You don't want it wet—just slightly "not-bone-dry."
Key Takeaway: Aim for a cool (40–55°F), dark, and slightly humid spot for storage. Airflow is essential to prevent rot.
Overwintering Cannas in Containers
If you grow your container-grown cannas in large pots, you have a "shortcut" option. You don't necessarily have to dig the rhizomes out of the soil. This is often a great choice for gardeners who want to save time or those who find digging large clumps to be physically demanding.
When the first frost hits, cut the foliage down to the soil level just as you would for garden-grown plants. Instead of digging, simply move the entire pot into a frost-free area like a basement or a heated garage. The dry soil in the pot acts as the storage medium.
Because the soil in a pot can dry out faster than rhizomes packed in peat moss, you may need to give the pot a tiny sip of water once every few weeks—just enough to keep the soil from becoming powdery. In the spring, you can pull the root ball out of the pot, divide the rhizomes if they have become crowded, and replant them with fresh soil.
Checking Your Cannas During the Winter
We suggest checking on your stored rhizomes at least once a month. This small effort can save your entire collection if something starts to go wrong.
When you check them, look for two things:
- Signs of Rot: If a rhizome feels soft, mushy, or has a sour smell, it is starting to rot. Use a clean knife to trim away the affected area until you reach healthy, firm white flesh. If the whole rhizome is soft, discard it immediately so it doesn't infect the others.
- Signs of Shriveling: If the rhizomes feel very light and the skin is wrinkled, they are losing too much moisture. Give your packing material a light misting of water to help them rehydrate.
By staying proactive, you can ensure that the vast majority of your cannas make it through to the spring in peak condition.
Preparing for Spring Replanting
As the days grow longer and the ground begins to warm, it's time to think about waking your cannas up. This is the most exciting part of the process, as you get to see the rewards of your winter care.
When to Plant
In most regions, cannas can go back into the garden once the danger of frost has passed and the soil temperature has reached about 60°F. Since cannas are tropical, they won't do much in cold, soggy spring soil. Waiting for the ground to warm up ensures they hit the ground running.
Dividing for More Plants
Spring is the best time to divide your rhizomes. If you started with one large clump in the fall, you might find you now have three or four viable sections. Look for "eyes"—the small, pointed bumps where new growth will emerge. Use a clean knife to cut the rhizomes into pieces, making sure each piece has at least one or two healthy eyes.
Starting Early Indoors
If you want blooms as early as possible, you can start your cannas indoors about 4 to 6 weeks before the last frost date. Plant the rhizomes in pots with potting soil and place them in a warm, sunny window. By the time the weather is warm enough to move them outside, you will already have several inches of lush green growth.
What to do next:
- Check your local last frost date on a gardening calendar.
- Inspect your stored rhizomes for "eyes" in early spring.
- Decide if you want to plant directly in the garden or start them in pots.
Conclusion
Wintering over canna lily bulbs is one of those simple gardening tasks that offers a massive return on investment. By taking a few hours in the fall to dig, cure, and store your rhizomes, you protect the beautiful plants you’ve come to love and set yourself up for an even more spectacular garden next year. Gardening is a journey of cycles, and there is a unique satisfaction in seeing a plant you cared for through the winter emerge from the soil once again.
We at Longfield Gardens are here to support you in creating a yard that brings you joy every season. Remember that every garden is a learning experience, and even if you lose a few rhizomes to the winter, you are gaining the skills to be a more confident gardener.
- Wait for the first frost before digging to ensure dormancy.
- Cure your rhizomes for a week to prevent rot during storage.
- Store them in a cool, dark, and well-ventilated spot.
- Check on them monthly to keep moisture levels just right.
"There is a special kind of magic in replanting a rhizome you saved yourself, knowing that the vibrant blooms of summer were preserved through your own care and timing."
As you look forward to the coming spring, we hope you feel encouraged to give this process a try. With a little bit of patience and the right storage conditions, your canna lilies will be ready to transform your garden with their tropical beauty once again.
FAQ
Can I store canna lilies in the refrigerator?
While a refrigerator is cool and dark, it is usually not the best place for canna rhizomes. The temperature in a fridge is often kept below 40°F, which can be too cold for tropical plants. Additionally, the lack of airflow and the presence of ripening fruits (which release gases) can cause the rhizomes to rot or fail to sprout. A cool basement or crawl space is a much more reliable option.
What if I forgot to dig my cannas and the ground froze?
If the ground only froze for a night or two, your rhizomes might still be okay, especially if they were planted deep. Dig them up as soon as possible and inspect them. If they are firm and white inside, they are likely fine to cure and store. If they feel soft or look "water-soaked," the frost has likely damaged the cells, and they may not survive the winter.
Do I need to use fungicide on my rhizomes before storing?
For most home gardeners, a fungicide is not necessary if you cure the rhizomes properly and use a dry storage medium like peat moss. However, if you have had recurring problems with rot in the past, you can lightly dust the cut ends of the rhizomes with powdered sulfur before packing them away. This provides an extra layer of protection against fungal growth.
How deep should I plant the rhizomes in the spring?
When it is time to move them back outside, plant your canna rhizomes about 4 to 5 inches deep. Position them horizontally in the soil with the "eyes" or growth points facing upward. Space them about 1 to 2 feet apart, depending on the variety, to give them plenty of room to spread their large leaves and soak up the summer sun.