Table of Contents
- Introduction
- Understanding Why We Winterize Cannas
- Identifying Your Hardiness Zone
- Timing: When to Move Cannas Indoors
- Tools for the Job
- How to Dig Canna Rhizomes Safely
- Cleaning and Preparing Your Rhizomes
- The Importance of Curing
- Dividing Your Canna Clumps
- Choosing Your Storage Medium
- Ideal Storage Conditions
- Winterizing Cannas in Containers
- Mid-Winter Maintenance Checks
- Waking Up Your Cannas in Spring
- Conclusion
- FAQ
Introduction
Watching a canna lily unfurl its lush, tropical leaves is one of the greatest rewards of a summer garden. These plants bring a bold, architectural presence and vibrant color to any backyard. If you’re looking to shop further, browse our cannas.
At Longfield Gardens, we want to help you enjoy those beautiful blooms year after year. For a taller statement next season, browse Tall Cannas.
While cannas are tropical plants, they do not have to be treated as one-season wonders. For more background on planning and growing them, see All About Cannas.
Winterizing canna bulbs is a straightforward process that allows you to save your favorite varieties for the next growing season. This guide is for any gardener who wants to protect their investment and see their plants come back bigger and better. By following a few simple steps, you can keep your canna rhizomes healthy and dormant until the warm weather returns.
Learning how to winterize canna bulbs is an essential skill for gardeners in cooler climates. It ensures that your garden remains a colorful oasis every summer without the need to start from scratch.
Understanding Why We Winterize Cannas
Canna lilies grow from thick, fleshy underground stems called rhizomes. In their native tropical environments, these rhizomes stay in the ground all year round. They don't experience the freezing temperatures common in many parts of the United States. In the US, cannas are considered "tender perennials." This means they live for many years but cannot survive a hard freeze.
If the ground freezes deep enough to reach the rhizomes, the water inside the plant cells expands and turns to ice. This causes the cells to burst, which leads to rot. Winterizing is simply the process of moving these tropical plants to a safe, frost-free place for their winter nap. It is a way of mimicking their natural dormant cycle in a controlled environment. If you prefer a versatile middle size for borders and containers, browse Medium Cannas.
When you take the time to store your cannas, you are rewarded with larger plants the following year. As canna rhizomes grow during the summer, they store up energy. This energy is what fuels the massive growth and bright flowers you see in July and August. Saving the same rhizomes allows that energy to accumulate, often resulting in more "eyes" or growing points.
Identifying Your Hardiness Zone
Before you grab your shovel, it is helpful to know if you actually need to dig up your cannas. This depends on your USDA hardiness zone. Most cannas are hardy in zones 8 through 11. In these areas, the ground rarely freezes deep enough to damage the rhizomes. If you live in these warm regions, you can usually leave your cannas in the ground year-round. Check the Hardiness Zone Map to see where your garden falls.
Gardeners in zone 7 live in a "swing" zone. In mild winters, cannas may survive in the ground if they are covered with a thick layer of mulch. Grass clippings, straw, or shredded leaves can act as an insulating blanket. However, if an unusually cold winter hits, even mulched cannas in zone 7 might struggle. Many gardeners in this zone choose to dig them up just to be safe.
If you live in zones 3 through 6, winterizing is a must. The cold temperatures in these regions will definitely reach the rhizomes if they are left outdoors. For these gardeners, digging and storing is the only way to ensure the plants return. We always recommend checking your local zone map to see where your garden falls.
Timing: When to Move Cannas Indoors
The best time to start the winterizing process is after the first light frost of autumn. You will know it has happened because the large, green or bronze leaves of your cannas will turn black or brown almost overnight. This might look disappointing, but it is actually a helpful signal from nature.
The frost tells the plant that the growing season is over. Once the foliage dies back, the plant stops sending energy upward and begins to focus entirely on its underground rhizomes. Leaving the plants in the ground for a few days after this first frost allows the rhizomes to finish their final stage of energy storage.
It is important to act before the ground itself freezes. While a light surface frost kills the leaves, a "hard freeze" or a "deep freeze" is what you want to avoid. If the soil temperatures drop too low, the rhizomes will be damaged. Keep an eye on your local weather forecast in late September or October. When you see the first frost predicted, get your storage supplies ready.
Tools for the Job
You do not need specialized equipment to winterize canna bulbs. Most of the tools are already in your garden shed. Having everything ready before you start makes the process quick and easy.
- A garden spade or fork: A garden fork is often better because it is less likely to slice through the rhizomes.
- Pruning shears or a sharp knife: These are used to cut back the foliage.
- A garden hose: Helpful for rinsing off excess soil.
- Storage containers: Cardboard boxes, plastic bins with air holes, or paper bags all work well.
- Packing material: Peat moss, vermiculite, perlite, or even old newspapers.
- Labels and a marker: This is the most forgotten but important tool. You want to remember which variety is which next spring!
How to Dig Canna Rhizomes Safely
When you are ready to dig, start by cutting the foliage back. Use your pruning shears to cut the stems about two to four inches above the soil line. These short "stumps" will serve as convenient handles when you are lifting the plants out of the dirt.
Next, give the plant some space. Canna rhizomes can grow quite large over a single summer. If you dig too close to the stem, you might accidentally chop a healthy rhizome in half. Aim your spade or fork about 6 to 10 inches away from the base of the plant.
Push the tool deep into the soil all the way around the clump. This loosens the roots and makes it easier to lift the entire mass at once. Gently pry upward. If the clump feels stuck, continue loosening the soil around the edges. Once the clump is loose, grab the stem handles and lift the cannas out of the ground.
Key Takeaway: Always dig wider than you think you need to. Canna rhizomes spread horizontally, and giving them extra space prevents accidental damage during the lifting process.
Cleaning and Preparing Your Rhizomes
Once the clumps are out of the ground, you will notice a lot of soil clinging to the roots. You have two choices for cleaning them: the "dry" method or the "wet" method. Both work well, but your choice might depend on your soil type.
If you have loose, sandy soil, you can often just shake the clumps. Much of the soil will fall away naturally. This is the easiest method and keeps the rhizomes dry. If you have heavy clay soil, the dirt might be stuck tight. In this case, use a garden hose with a gentle spray to wash the soil away. Do not use a high-pressure setting, as this can tear the delicate skin of the rhizomes.
After cleaning, take a moment to inspect your cannas. Look for any parts that feel soft, mushy, or smell unpleasant. These are signs of rot. Use a clean, sharp knife to trim away any damaged sections. You want only firm, healthy rhizomes going into storage. Healthy rhizomes are usually white, tan, or pinkish in color and feel like a firm potato. For a fuller overview of canna care, see How to Care for Canna Lily Bulbs.
The Importance of Curing
Curing is a step that many beginner gardeners skip, but it makes a big difference in storage success. Curing is the process of letting the rhizomes air-dry for a few days before packing them away. This allows the outer skin to toughen up and any small nicks or cuts to "callus" over.
Place your cleaned rhizomes in a single layer in a dry, well-ventilated area. A garage, a shed, or a covered porch works perfectly. Keep them out of direct sunlight and away from freezing temperatures. Let them sit for about three to seven days.
During this time, the excess moisture on the surface evaporates. This is crucial because trapped moisture is the leading cause of mold and rot during the winter months. Once the rhizomes feel dry to the touch and the cut ends look "scabbed" over, they are ready for their final storage container.
- Step 1: Cut stems to 3 inches.
- Step 2: Dig 8 inches away from the plant.
- Step 3: Clean off the soil (shake or rinse).
- Step 4: Let them dry (cure) in a cool spot for a few days.
Dividing Your Canna Clumps
Fall is a great time to divide your cannas, though you can also do it in the spring. If your canna clumps have become very large and heavy, dividing them now makes storage much easier. Each section of the rhizome needs at least one or two "eyes" to grow into a new plant. Eyes look like small, rounded bumps or points on the rhizome, similar to the eyes on a potato.
You can often pull the rhizomes apart by hand. If they are too tough, use a clean knife to slice them into smaller sections. At Longfield Gardens, we recommend keeping the sections fairly large—about the size of your fist. Larger sections have more stored energy, which leads to a more vigorous plant in the spring. If you want an easy mix, browse the Canna Assorted Collection.
If you divide them in the fall, make sure to let the fresh cuts dry and callus during the curing process. This prevents pathogens from entering the plant while it is dormant. Dividing is the best way to expand your garden for free or to have extra plants to share with friends and neighbors.
Choosing Your Storage Medium
The goal of storage is to keep the rhizomes in a state of "suspended animation." You want them to stay cool enough to remain dormant, but you also want to prevent them from drying out completely. This is where your storage medium comes in.
Popular choices include:
- Peat Moss: This is the most common choice. It holds a tiny bit of moisture but stays fluffy enough to allow air circulation.
- Vermiculite or Perlite: These are sterile and very effective at regulating moisture.
- Wood Shavings: Often sold as pet bedding, these are inexpensive and work well.
- Newspaper: Wrapping individual rhizomes in layers of dry newspaper is a simple, old-fashioned method that still works today.
Whatever you choose, the goal is to cushion the rhizomes and provide a buffer against changes in humidity. If the storage environment is too dry, the rhizomes will shrivel. If it is too wet, they will rot. The storage medium helps maintain that perfect middle ground.
Ideal Storage Conditions
The location where you keep your cannas over the winter is just as important as how you pack them. The ideal temperature range is between 40°F and 50°F. This is cool enough to keep the plant dormant but warm enough that it won't freeze.
A dark basement, a crawl space, or a cool closet in an unheated part of the house are usually the best spots. Avoid rooms with active heating vents, as the air will be too dry and warm. Also, avoid unattached garages or sheds that might drop below freezing during a cold snap. If the temperature stays above 60°F, the cannas might try to start growing too early.
Place your rhizomes in a box or bin and cover them with your chosen storage medium. If you are using plastic bins, do not snap the lid on tight. Leave it slightly ajar or drill several small holes in the sides of the bin. Cannas are living things, even when dormant, and they need a small amount of oxygen to stay healthy.
Winterizing Cannas in Containers
If you grow your cannas in pots, you have a shortcut! You don't necessarily need to dig the rhizomes out of the soil. When the frost hits and the foliage turns brown, cut the stems down to the soil level as usual. Then, move the entire pot into your cool, dark storage area. For more ideas on growing them in pots, see How to Grow Summer Bulbs in Containers.
The soil in the pot acts as a natural storage medium. It protects the rhizomes from temperature swings and keeps them from drying out too fast. One thing to remember is to stop watering once you move the pot indoors. The soil should be dry or only very slightly damp throughout the winter. For a more compact container option, browse Short Cannas.
In the spring, you can bring the pot back out into the sun, give it a good soak, and wait for the new shoots to appear. Every few years, you will still need to dump the pot out and divide the rhizomes, as they will eventually become "root-bound" and run out of space to grow.
Key Takeaway: Storing cannas in their original pots is the easiest way to overwinter them, provided you have a cool, frost-free space to keep the entire container.
Mid-Winter Maintenance Checks
Winterizing isn't a "set it and forget it" task. It is a good idea to check on your stored cannas once a month. This only takes a few minutes and can save your whole collection if a problem starts.
Open your boxes and feel a few of the rhizomes. If they feel extremely dry, shriveled, or light, they might be losing too much moisture. You can lightly mist the storage medium with a spray bottle of water. You don't want it wet—just slightly damp to the touch.
If you find a rhizome that feels soft or shows signs of fuzzy mold, remove it immediately. Rot can spread from one rhizome to another if they are touching. By removing the "bad apple" early, you protect the rest of the bunch. This simple monthly check ensures that you have healthy plants ready to go when spring finally arrives.
Waking Up Your Cannas in Spring
As the days get longer and the weather warms up, you will start thinking about your garden again. You can "wake up" your cannas about four to six weeks before the last expected frost date in your area. This gives them a head start on the season. If you want to start them early indoors, follow How to Start Planting Canna Bulbs Indoors.
Bring the rhizomes out of storage and inspect them one last time. They should still feel firm. If you haven't divided them yet, now is a great time to do it. You can plant them in pots indoors and place them in a sunny window. Use a standard potting mix and start watering them lightly.
Once the soil outside has warmed up to about 60°F and the danger of frost has completely passed, you can transplant them into the garden. Cannas love sun and rich soil, so choose a spot where they can soak up the heat. For a refresher on planting depth, see How Far Down Do You Plant Canna Bulbs?. With the head start you gave them, they will bloom much earlier than if you had planted them directly in the cold ground.
Conclusion
Winterizing canna bulbs is a rewarding part of the gardening cycle. It transforms a one-time purchase into a lifelong collection of tropical beauty. By waiting for the frost, digging carefully, and providing a cool, dry home for the winter, you ensure your garden will be spectacular next year. Gardening is a journey of patience and care, and the effort you put in now will pay off in vibrant colors and lush foliage come summer.
At Longfield Gardens, we believe that every gardener can be successful with cannas. These resilient plants are eager to grow, and they respond wonderfully to a little winter protection. We stand behind that with our 100% Quality Guarantee.
- Wait for the first frost to signal dormancy.
- Cure rhizomes for a week to prevent rot.
- Store in a cool, dark place between 40°F and 50°F.
- Check monthly for moisture and health.
"The secret to a stunning summer garden often lies in the care we provide during the quiet winter months."
Your next step is to find a cool spot in your home that stays consistently between 40 and 50 degrees. Once you have your storage location picked out, you are ready to give your cannas the winter rest they deserve. If you’re planning ahead for new plantings, browse Spring-Planted Bulbs.
FAQ
Do I have to wait for a frost before digging up cannas?
While you don't strictly have to wait for a frost, it is highly recommended. A light frost sends a chemical signal to the rhizome to go dormant and store energy for the winter. If you must dig them earlier, simply cut the foliage back and follow the same cleaning and curing steps.
Can I store canna rhizomes in the refrigerator?
A refrigerator is usually too cold and too dry for long-term canna storage. Temperatures in a fridge are typically around 35-38°F, which can damage the tropical tissue of the rhizome over several months. A cool basement or a dark, unheated closet is a much better environment.
What happens if I don't wash the dirt off my canna bulbs?
You can store cannas with some soil still attached, and many gardeners do this successfully. However, washing them allows you to inspect the rhizomes more clearly for rot or pests. It also prevents you from bringing garden soil and potential insects into your home or storage area.
My stored canna rhizomes look shriveled. Are they dead?
Not necessarily! A little bit of shriveling is normal as the rhizome loses moisture. If they are still firm when you squeeze them, they are likely still alive. Give them a light misting of water and check them again in a week. If they are hollow or mushy, then they are no longer viable.