Table of Contents
- Introduction
- Understanding Canna Lily Dormancy
- When to Begin the Overwintering Process
- How to Lift Canna Rhizomes Properly
- Cleaning and Curing for Success
- Storage Methods and Materials
- Overwintering Cannas in Containers
- Monitoring Your Plants During Winter
- Preparing for Spring Reawakening
- Common Questions and Realistic Expectations
- Conclusion
- FAQ
Introduction
Bringing a touch of the tropics to your backyard is one of the greatest rewards of the summer gardening season. With their massive, paddle-shaped leaves and vibrant, orchid-like blooms, canna lilies transform any space into a lush oasis. These plants are beloved for their ability to thrive in the summer heat and provide height and drama to garden borders and patio containers alike. At Longfield Gardens, we enjoy helping you bring these spectacular displays to life every year with our Assorted Cannas, true to variety and ready to perform.
As the season winds down and the first hints of autumn appear, many gardeners wonder how to protect their tropical treasures. While cannas are perennials in warm climates, they require a bit of extra care in regions where the ground freezes. Understanding how to handle overwintering canna lily bulbs is the key to ensuring your favorite varieties return even bigger and better the following summer.
This guide will walk you through the simple, rewarding process of lifting, cleaning, and storing your canna rhizomes. Whether you are a beginner or a seasoned gardener, you will find that preserving these plants is an easy way to build a beautiful, sustainable garden year after year. By following a few basic steps, you can keep your garden’s tropical spirit alive throughout the winter months.
Understanding Canna Lily Dormancy
To successfully overwinter your cannas, it helps to understand what the plant is doing as the weather cools. All About Cannas offers a broader look at planting, growing, and storing these tropical bulbs.
Cannas are tropical and subtropical plants that grow from rhizomes—thick, fleshy underground stems that store energy. While many people refer to them as "bulbs," they behave more like iris or ginger roots. This energy storage is what allows the plant to go dormant during the winter and sprout with vigor once the soil warms up in the spring.
In their native habitats, cannas do not experience a hard freeze. Instead, they might have a period of slower growth during drier or cooler months. In a typical US garden, dormancy is triggered by the arrival of cold temperatures. When the thermometer begins to drop, the plant stops producing new leaves and flowers. It shifts all its focus toward pushing nutrients back down into the rhizome. This process is essential for the plant’s survival and for next year’s bloom quality.
The Role of Temperature
Cannas are generally hardy in USDA Zones 8 through 11. In these warmer regions, the ground rarely freezes deep enough to damage the rhizomes. Gardeners in these areas can often leave their cannas in the ground year-round with a bit of mulch for protection. However, in Zones 7 and colder, the freezing and thawing of the soil can cause the moisture-rich rhizomes to rot or freeze, which effectively kills the plant. If you're unsure of your zone, our Hardiness Zone Map is a quick place to check.
For those of us in cooler climates, overwintering is a way of mimicking a tropical "dry season." We provide a cool, dark, and frost-free environment that keeps the plant in a state of rest without allowing it to dry out completely.
Why Overwintering is Worth the Effort
While you can certainly buy new cannas every spring, there is a special satisfaction in seeing your own plants return. Over time, canna rhizomes grow and multiply. A single rhizome planted in May can turn into a large clump by October. By lifting and storing them, you are not just saving a plant; you are expanding your garden. A Canna Assorted Mix - Bulk Offer is an easy way to keep that momentum going next season.
Key Takeaway: Overwintering cannas is a simple way to protect your garden investment and ensure a larger, more impressive display of tropical foliage and flowers each year.
When to Begin the Overwintering Process
Timing is everything when it comes to lifting cannas. You want to give the plant as much time as possible to store energy, but you must act before the ground freezes solid. The most common signal to start is the first "blackening" frost.
Watching the Weather
In most regions, a light frost will kill the top growth of the canna lily, turning those lush green or bronze leaves to a dark brown or black. This may look a bit sad at first, but it is actually a helpful signal from nature. This "frost-kill" tells the plant that the growing season is officially over and it is time to go to sleep.
It is perfectly safe to leave the rhizomes in the ground for a few days after the first frost has hit the foliage. In fact, many gardeners believe that a light frost helps trigger a deeper dormancy, which can lead to better storage results. However, you should aim to have your cannas lifted and moved to safety before the ground itself begins to freeze.
Indicators for Lifting
- Foliage Color: Leaves turn brown, black, or wilted after a night of 32°F or lower.
- Calendar Date: Depending on your zone, this usually happens between late September and early November.
- Soil Condition: Dig while the soil is still workable and not waterlogged from autumn rains.
What to do next: Once you see the foliage turn black after the first frost, gather your garden fork, labels, and storage containers. This is the ideal window to begin the lifting process.
How to Lift Canna Rhizomes Properly
Lifting cannas is a straightforward task, but doing it with care ensures the rhizomes remain healthy and free of damage. Damage to the "skin" of the rhizome can create entry points for rot during the winter, so a gentle hand is best.
Step 1: Cutting Back the Foliage
Before you start digging, you need to clear away the dead top growth. Use a clean pair of garden shears or a sharp knife to cut the stems down. We recommend leaving about 2 to 4 inches of stem protruding from the rhizome. These "stubs" serve as convenient handles during the lifting process and help you identify which way is up when you replant them in the spring.
Step 2: Digging the Clump
Cannas can spread quite a bit during the summer, and the rhizomes may be further from the center than you think. For next season’s big, bold display, browse the Tall Cannas collection.
Use a garden fork rather than a shovel if possible. A fork allows you to loosen the soil and lift the clump from underneath with less risk of cutting the plant. Slowly work your way around the plant, prying upward until the entire root mass feels loose. Once it is free, lift the clump out of the ground.
Step 3: Initial Cleaning
Once the clump is out of the ground, gently shake it to remove large chunks of soil. Do not worry about getting them perfectly clean just yet. You can use your hands to brush away loose dirt, but avoid using a high-pressure hose, as you don't want to saturate the rhizomes right before they go into storage.
If the soil is very sticky or made of heavy clay, you can use a light spray of water to see what you are working with, but you must ensure the rhizomes dry out completely afterward.
Cleaning and Curing for Success
After lifting, the rhizomes need a short "rest" period before they are packed away for the winter. This phase is known as curing. Curing allows the outer skin of the rhizome to toughen up and any small nicks from the digging process to callus over.
The Curing Process
Move your lifted clumps to a protected area that is dry and out of direct sunlight. A garage, garden shed, or even a covered porch works well. Lay them out in a single layer on a piece of cardboard or a newspaper.
Let the rhizomes air dry for about 2 to 7 days. You want the exterior to feel dry to the touch and any remaining soil to turn into a dry powder that easily brushes off. Curing is a vital step because excess moisture is the primary cause of rot during winter storage.
To Divide or Not to Divide?
Many gardeners ask if they should divide their canna clumps in the fall or wait until spring. While you can do either, there are benefits to both:
- Fall Division: If you have limited storage space, dividing the clumps into individual rhizomes now will save room. It also allows you to inspect each piece for health.
- Spring Division: Many find that keeping the large clumps intact helps prevent the rhizomes from drying out too much over the winter. In the spring, the "eyes" (growth points) will be more visible, making it easier to see exactly where to make your cuts.
If you do choose to divide them in the fall, ensure each piece has at least one or two "eyes." Use a sharp, sterilized knife and allow the cut ends to dry and callus for an extra day before packing.
Storage Methods and Materials
The goal of storage is to keep the rhizomes in a "Goldilocks" environment: not too cold, not too warm, and just the right amount of humidity. They should be kept in a dark place where the temperature stays consistently between 40°F and 50°F. For a more detailed walkthrough, see How to Divide and Store Canna Bulbs.
Choosing Your Storage Medium
You should never store canna rhizomes in airtight plastic bags, as the lack of airflow will lead to mold. Instead, use breathable containers like cardboard boxes, paper bags, or plastic bins with holes drilled in the sides. To keep the rhizomes from shriveling, we recommend surrounding them with a packing medium.
- Peat Moss or Coco Coir: These are popular choices because they hold a tiny bit of moisture while remaining breathable.
- Vermiculite or Perlite: These sterile minerals are excellent for moisture regulation and are very lightweight.
- Wood Shavings: Often sold as pet bedding, these provide good insulation and airflow.
- Newspaper: If you don't have other materials, wrapping individual rhizomes in several layers of dry newspaper is a simple and effective method.
Packing the Containers
Start by placing a 2-inch layer of your chosen medium at the bottom of the box. Arrange the rhizomes in a single layer so they are not touching each other. This prevents a single "bad apple" from spreading rot to the rest. Cover them with more medium and repeat the process if your container is deep enough.
Key Takeaway: Proper storage requires a breathable container and a medium that regulates moisture, ensuring the rhizomes stay dormant and healthy until spring.
Overwintering Cannas in Containers
If you grow your cannas in large pots, you have a slightly easier path, and container-friendly cannas are a good fit.
The "Pot-and-All" Method
Once the frost has killed the foliage, cut the stems back to 2 inches as you would with in-ground plants. Move the entire container into a frost-free area like a basement or a cool garage. The dry soil in the pot acts as the storage medium.
The most important rule for container overwintering is to stop watering. The soil should remain dry throughout the winter. If the soil stays wet while the plant is dormant, the rhizomes will rot very quickly. In the spring, you can simply move the pot back outside, refresh the top inch of soil, and start watering to wake them up.
When to Repot
If your canna has been in the same pot for several years, it may become "root-bound" or "rhizome-bound." The pressure of the growing rhizomes can even crack plastic or ceramic pots. In this case, it is better to tip the pot over in the fall, shake out the rhizomes, and store them using the box method described earlier. The Medium Cannas collection offers mid-sized options for the same easy-care look.
Monitoring Your Plants During Winter
Overwintering isn't a "set it and forget it" task. To ensure the highest success rate, we recommend checking on your stored rhizomes about once a month.
What to Look For
When you open your storage boxes, look for two main issues: rot and desiccation (drying out).
- Checking for Rot: If a rhizome feels soft, mushy, or has a foul odor, it is starting to rot. Remove it immediately and throw it away. If only a small part of a large clump is affected, you can sometimes cut away the soft tissue with a clean knife, let the cut dry, and return the healthy portion to storage.
- Checking for Drying: If the rhizomes look very shriveled or feel extremely light and brittle, they are losing too much moisture. Use a spray bottle to lightly mist the packing medium (not the rhizomes directly). You want the medium to feel barely damp, like a wrung-out sponge.
Maintaining the Environment
If you notice your rhizomes are starting to sprout prematurely in January or February, your storage area is likely too warm. Try to move them to a cooler spot. On the other hand, if a sudden cold snap threatens to bring your garage temperature below freezing, throw an old blanket over your storage boxes for extra insulation.
What to do next: Set a recurring reminder on your calendar to check your stored bulbs once a month. This small step can be the difference between success and disappointment in the spring.
Preparing for Spring Reawakening
As the days get longer and the ground begins to thaw, it is time to think about bringing your cannas out of storage. This is often the most exciting part of the process, as it marks the beginning of a new garden year.
Inspecting the Final Harvest
In late March or April, take the rhizomes out of their boxes for a final inspection. They should feel firm and heavy. You may already see small white or pink "eyes" beginning to swell at the tips. This is a great sign that the plant is ready to grow.
If you didn't divide your clumps in the fall, now is the time. Use a sharp knife to cut the clumps into sections, ensuring each piece has at least one prominent eye. Let the cuts dry for 24 hours before planting.
Starting Cannas Early Indoors
If you live in a region with a short growing season, you can get a head start by potting up your rhizomes indoors about 4 to 6 weeks before the last frost. How to Plant a Canna Bulb is a helpful companion guide for that early start.
- Fill a pot with well-draining potting soil.
- Plant the rhizome about 3 to 4 inches deep with the eyes facing up.
- Place the pot in a warm, sunny window or under grow lights.
- Water sparingly at first, increasing moisture as the first leaves appear.
Starting them early ensures that you will have established plants ready to go into the ground as soon as the weather is warm, leading to earlier blooms in the summer.
Common Questions and Realistic Expectations
Gardening is a partnership with nature, and while the steps above provide a reliable path to success, results can vary based on your local climate and storage conditions. It is normal to lose a few rhizomes over the winter, especially if it was a particularly humid or unusually cold season.
Drainage is the Quiet Winner
One of the most important things to remember when you replant in the spring is that cannas love water while they are growing, but they hate "wet feet" while they are dormant or just starting out. Always ensure your garden beds have good drainage and your pots have plenty of holes. Adding a bit of compost or grit to heavy soil can help keep the rhizomes happy.
Right Plant, Right Place
When you move your overwintered cannas back into the garden, remember their basic needs. They crave full sun—at least 6 to 8 hours a day. The more sun they get, the more vibrant their leaf colors will be and the more flowers they will produce.
"The secret to a great canna display is patience in the spring and protection in the winter. Once they feel the heat of the summer sun, they will reward your efforts tenfold."
Conclusion
Overwintering canna lily bulbs is a rewarding practice that bridges the gap between garden seasons. By taking the time to lift and store these tropical beauties, you are participating in a cycle of growth that makes your garden more personal and sustainable. From the first frost that signals the end of the year to the exciting moment you see the first green shoots in the spring, the process is full of quiet, satisfying steps.
At Longfield Gardens, we want you to feel confident in your ability to grow and maintain a stunning landscape. Whether you are storing a few favorite tubers or a large collection of varieties, the key is to keep things simple: watch the weather, keep the rhizomes dry and cool, and wait for the warmth of spring to start the cycle again. If you want a more dramatic display next season, the tall canna varieties collection is a great place to start.
Takeaways for Success:
- Wait for the first frost to blacken the foliage before lifting.
- Cure the rhizomes in a dry, shaded area for several days.
- Store in a breathable container with a medium like peat moss or wood shavings.
- Check monthly for rot or excessive drying.
As you plan your next garden, remember that the quality plants we provide at Longfield Gardens are meant to bring you joy for years to come. With a little winter care, your canna lilies will continue to be the star of your summer show.
FAQ
How do I know if my canna rhizomes are still good after winter?
Healthy rhizomes should feel firm and heavy in your hand, similar to a fresh potato. If they are soft, mushy, or crumble when touched, they have likely rotted or dried out too much and should be discarded. You may also see small, colorful "eyes" or buds starting to sprout as spring approaches, which is a sure sign of life.
Do I need to wash the soil off the rhizomes before storing them?
It is best to remove as much soil as possible, but you don't need them to be perfectly clean. Brushing off dry soil after the curing period is usually sufficient. If you do use water to wash them, make sure they are completely dry before you pack them away, as trapped moisture is the main cause of winter rot.
Can I store canna bulbs in a refrigerator?
While a refrigerator is cool and dark, it is generally too cold and often too humid for canna rhizomes. Most refrigerators are kept around 35°F–38°F, which can damage tropical plants. A cool basement, crawl space, or insulated garage that stays between 40°F and 50°F is a much better choice for long-term storage.
What happens if I forget to dig up my cannas before the ground freezes?
If the ground freezes solid, the water inside the fleshy rhizomes will turn to ice, expanding and destroying the plant's cell structure. Once they thaw, they will likely turn to mush. If you experience a sudden, unexpected freeze, dig them up as soon as possible and inspect them; if they are still firm, they may have survived, but if they are soft, they likely won't recover.