Table of Contents
- Introduction
- Understanding Canna Dormancy and Timing
- Preparing to Dig: The First Steps
- How to Dig Canna Rhizomes Safely
- The Curing Process: Why Air-Drying is Vital
- Choosing the Right Storage Packing Material
- Step-by-Step Packing for the Winter
- Finding the Ideal Storage Location
- The Importance of the Monthly Winter Check
- Dividing Canna Rhizomes: Now or Later?
- Storing Container-Grown Cannas
- Waking Up Your Cannas in Spring
- Troubleshooting Winter Storage Issues
- Summary of Canna Storage Success
- FAQ
Introduction
There is nothing quite like the tropical flair that cannas bring to a summer garden. With their lush, oversized foliage and vibrant blooms in shades of red, orange, and yellow, they transform any backyard into an exotic retreat. At Longfield Gardens, we believe that the beauty of these cannas should be something you can enjoy year after year. While cannas are tender perennials, they are remarkably easy to save once the growing season comes to an end.
If you live in a region that experiences freezing temperatures, learning how to store canna bulbs—technically known as rhizomes—is the key to a sustainable and rewarding garden. This process allows you to keep your favorite varieties and even expand your canna collection over time as the plants naturally multiply. In this guide, we will walk you through the simple, effective steps to harvest, clean, and store your canna rhizomes so they emerge healthy and ready to grow when spring returns. Storing your cannas is a straightforward task that ensures your garden will be filled with tropical color for many seasons to come.
Understanding Canna Dormancy and Timing
The most successful winter storage starts with listening to the natural cues of your garden. Cannas are tropical plants by nature, but they have a built-in mechanism for survival called dormancy. This is a period of rest where the plant stops active growth and stores energy in its fleshy rhizomes. Knowing when to trigger this rest period is the most important part of the process.
The Role of the First Frost
In most climates, the signal to begin the storage process is the first light frost of autumn. You will notice the vibrant green or bronze leaves of your cannas turning brown or even black after a chilly night. While this might look like the end of the plant’s life, it is actually a vital signal. The cold temperature tells the plant to move all its remaining nutrients down from the leaves and into the rhizome.
Waiting for this first frost is generally recommended because it ensures the rhizome is as "charged" as possible for the winter months. However, you do not need to wait for a hard, ground-freezing freeze. A light frost that singes the foliage is the perfect indicator that it is time to get your garden tools ready.
Why Regional Climate Matters
Your specific USDA hardiness zone determines whether you actually need to dig your cannas. We generally recommend that gardeners in zones 6 and colder dig and store their cannas every winter. In these regions, the ground freezes deep enough to reach the rhizomes, which would cause them to rot and fail to return.
If you are in zone 7, you are in a "transition" area. Many gardeners here find success leaving cannas in the ground if they provide a thick layer of mulch—about 6 to 8 inches of straw or shredded leaves—to act as insulation. However, a particularly harsh winter can still be a risk. If you have a variety you truly love, digging it up is the only way to ensure its safety. For those in zones 8 through 11, cannas can typically remain in the ground year-round, as the soil temperature rarely drops low enough to cause damage.
Key Takeaway: The first light frost is your green light to start the digging process. It signals the plant to go dormant and move energy into the rhizome for winter survival.
Preparing to Dig: The First Steps
Once the foliage has been hit by frost, the preparation for storage begins. Before you even touch a shovel, you need to manage the top growth of the plant.
Cutting Back the Foliage
Use a clean pair of garden shears or a sharp knife to cut the stalks down. You should aim to leave about 4 to 6 inches of the stem protruding from the ground. This remaining "handle" serves two purposes: it helps you locate the center of the root mass as you dig, and it acts as a marker if you are storing different varieties and want to keep them organized.
Discard the frost-damaged leaves in your compost pile or green waste bin. Clearing the area around the base of the plant will give you a better view of the workspace and help you avoid accidentally damaging the rhizomes with your tools.
Selecting the Right Tools
A garden fork or a spade shovel is the best tool for this job. A garden fork is often preferred because it allows you to loosen the soil around the rhizomes with less risk of slicing through the fleshy structures. If you use a spade, you will need to be extra cautious about where you place your blade.
How to Dig Canna Rhizomes Safely
The goal when digging is to lift the entire clump of rhizomes out of the earth in one piece without bruising or cutting them. Canna rhizomes are fleshy and can be somewhat brittle. Any wounds or "skin breaks" on the rhizome can become entry points for fungi or bacteria during the storage period.
The Wide-Circle Method
Instead of digging directly at the base of the stems, start your digging circle about 8 to 12 inches away from the stalks. Push your shovel or fork deep into the soil and gently pry upward. Move around the plant in a circle, loosening the soil from all sides.
Once the soil is loose, you can place your tool underneath the clump and lift it gently toward the surface. If the clump is particularly large, you might need a partner to help lift, or you can slowly work the soil away with your hands until the mass is light enough to move.
Cleaning the Rhizomes
Once the clump is out of the ground, shake it gently to remove large clods of soil. You can also use your fingers to brush away excess dirt. Some gardeners prefer to use a gentle stream of water from a garden hose to wash the rhizomes clean. This makes it much easier to see the health of the rhizomes and identify the "eyes" (the small bumps where next year's growth will emerge).
If you do wash them, it is critical that you allow them to dry completely before moving to the next step. Moisture is the biggest enemy of successful winter storage, so a dry rhizome is a safe rhizome.
Action Checklist: Digging and Cleaning
- Cut stalks down to 4–6 inches after the first frost.
- Dig a wide circle (12 inches out) to avoid tool damage.
- Lift the clump gently using a garden fork or spade.
- Brush off loose soil or rinse gently with a hose.
- Ensure rhizomes are moved to a dry area immediately after cleaning.
The Curing Process: Why Air-Drying is Vital
Curing is a step that many beginner gardeners overlook, but it is essential for long-term success. Curing is simply the process of allowing the outer skin of the rhizome to dry and toughen up slightly. This creates a natural protective barrier against rot and desiccation (drying out too much).
Where to Cure
Find a dry, frost-free location with good air circulation. A garage, a covered porch, or a basement work well. Spread the rhizomes out in a single layer on a piece of cardboard, newspaper, or a wire rack. Avoid piling them on top of each other, as this can trap moisture and lead to mold.
How Long to Cure
Under normal conditions, canna rhizomes only need to cure for 1 to 3 days. You aren't looking to dry them out until they are shriveled; you just want the outer surface to feel dry to the touch and any remaining soil to be crumbly and easy to brush off. If the weather is particularly humid, you may need an extra day. Once they are cured, they are ready for their final winter home.
Choosing the Right Storage Packing Material
You cannot simply throw canna rhizomes into a plastic bin and expect them to thrive. They need a storage medium that regulates moisture—something that keeps them from drying out completely while also absorbing any excess humidity that could cause rot.
Popular Packing Options
There are several excellent materials you can use to pack your cannas:
- Peat Moss: This is the most common choice. It is naturally sterile and does a fantastic job of holding just enough moisture to keep the rhizomes plump.
- Vermiculite or Perlite: These lightweight minerals provide excellent aeration and moisture control.
- Wood Shavings or Sawdust: Often used for animal bedding, these are inexpensive and effective at protecting rhizomes.
- Newspaper: If you don't have access to other materials, wrapping individual rhizomes in several layers of dry newspaper is a simple and traditional method.
Containers for Storage
Your container should allow for a small amount of airflow. Cardboard boxes, plastic bins with holes drilled in the sides, or breathable burlap bags are all great options. If you use a plastic tote, keep the lid slightly ajar or drill several 1/2-inch holes around the top edges to prevent stagnant air from building up.
Step-by-Step Packing for the Winter
Now that your rhizomes are clean, cured, and your materials are ready, it is time to pack them away.
- Layer the Bottom: Place a 2-inch layer of your chosen packing material (like peat moss or wood shavings) at the bottom of the container.
- Arrange the Rhizomes: Place the rhizomes on top of the layer, ensuring they are not touching each other. Keeping space between them prevents the spread of rot if one individual rhizome happens to fail.
- Cover and Repeat: Add more packing material until the rhizomes are completely covered. If your container is deep, you can add a second layer of rhizomes and cover those as well.
- Label Everything: If you have different colors or varieties, be sure to label the box or include a tag inside. It is easy to forget which is which by the time spring arrives!
If you want to start with more rhizomes at once, consider the Canna Assorted Mix - Bulk Offer for next season.
Finding the Ideal Storage Location
The location where you keep your packed cannas will determine their survival. Cannas need a spot that is "just right"—not too hot, not too cold, and not too bright.
Temperature Requirements
The ideal temperature for storing canna bulbs is between 45°F and 55°F (7°C to 13°C).
- If it’s too cold: If the temperature drops below freezing, the water inside the fleshy rhizomes will freeze, expand, and destroy the cell walls, leading to mushy, dead plants.
- If it’s too warm: If the temperature stays above 60°F, the rhizomes may think it is time to grow and start sprouting prematurely, or they may dry out too quickly.
Common Storage Spots
An unheated basement, a crawl space, or a cool closet in a mudroom are usually the best spots. An attached garage can work, but you must be certain that the temperature stays above freezing during the coldest nights of the year. If you use a garage, place the boxes on a shelf rather than directly on the cold concrete floor.
Key Takeaway: Success lies in the "Goldilocks" zone of 45–55°F. Keeping your containers in a dark, cool, and frost-free environment ensures the rhizomes stay dormant until spring.
The Importance of the Monthly Winter Check
Storing your cannas isn't a "set it and forget it" task. We recommend checking on your stored rhizomes once a month throughout the winter. This five-minute check can save your entire collection.
What to Look For
When you open your storage boxes, look for two main things:
- Signs of Rot: If you see any rhizomes that have turned soft, mushy, or have visible fuzzy mold, remove them immediately. This prevents the rot from spreading to the healthy rhizomes.
- Signs of Desiccation: If the rhizomes look very wrinkled or feel extremely light and brittle, they are losing too much moisture.
How to Fix Issues
If the rhizomes are drying out, use a spray bottle to lightly mist the packing material with water. You don't want it to be wet—just slightly damp. This small amount of humidity will help the rhizomes stay plump. If the material feels damp or you see condensation on the walls of the container, remove the lid for a day or two to improve airflow.
Dividing Canna Rhizomes: Now or Later?
As cannas grow, they naturally expand and create new "pups" or offsets. This means that a single rhizome you planted in May might become a large clump of five or six by October. You will eventually need to divide these to keep the plants healthy and manageable. For more growing background, read All About Cannas.
When to Divide
You can divide cannas either in the fall before you pack them away or in the spring before you replant them.
- Fall Division: This saves storage space, as you aren't storing large, bulky clumps.
- Spring Division: This is often easier for beginners because you can clearly see the "eyes" starting to swell, making it obvious where to make your cuts.
How to Divide
Use a sharp, clean knife to cut the rhizome into sections. Each section must have at least one—and preferably two or three—prominent "eyes." These eyes are the growth points that will produce the leaves and flowers. If a section of rhizome has no eyes, it will not grow. Allow the cut surfaces of the rhizomes to dry and "callus" over for a day before planting or storing.
Storing Container-Grown Cannas
If you grow your cannas in large pots or decorative containers, you have a slightly easier option for winter storage. Instead of digging the rhizomes out of the soil, you can store the entire pot.
For more ideas on pot culture, see Best Summer Bulbs for Containers.
- Cut back the foliage after the first frost, just as you would for in-ground plants.
- Move the pot to a cool, dark, and frost-free location like a basement or garage.
- Stop watering. The soil should be allowed to dry out significantly.
- Check monthly. The soil shouldn't become bone-dry or like concrete; a tiny bit of water once every month or two is usually enough to keep the dormant rhizomes alive.
In the spring, you can simply move the pot back into the sun and resume watering, or you can tip the pot over, refresh the soil, and divide the rhizomes if they have become crowded.
Waking Up Your Cannas in Spring
When the days begin to lengthen and the threat of hard frost has passed, it is time to think about the new growing season. Depending on your climate, you may want to give your cannas a "head start."
Starting Indoors
In northern zones with short summers, many gardeners pot up their stored rhizomes in containers about 4 to 6 weeks before the last expected frost. Use a standard potting mix and place the pots in a warm, sunny window. This allows the plants to develop roots and a few inches of growth before they even move outside, leading to earlier blooms in the garden.
For more canna inspiration, read Fresh Ideas for Growing Cannas in Your Garden.
Planting Directly Outside
If you prefer to plant directly into the ground, wait until the soil has warmed to at least 60°F. Cannas love heat and will sit dormant in cold, wet soil, which can lead to rot. Once the weather is consistently warm, plant your rhizomes about 4 inches deep and 1 to 2 feet apart.
Action Summary: Spring Preparation
- Check rhizomes one last time for firmness and health.
- Divide large clumps if you didn't do so in the fall.
- Pot up 4–6 weeks early for a head start on blooms.
- Only move outside once the soil is warm and frost is gone.
- Water sparingly at first, increasing as growth appears.
Troubleshooting Winter Storage Issues
Even with the best care, sometimes things don't go exactly as planned. Here is how to handle the most common issues with a positive approach.
My Rhizomes are Mushy
If you find a mushy rhizome, it was likely too wet when it was packed or the storage area was too humid. Don't worry—simply discard the affected piece and check the others. If the packing material feels damp, replace it with fresh, dry material and ensure your container has better ventilation.
My Rhizomes are Shrivelled
This is the result of low humidity. The rhizome has used up its internal water reserves. If the rhizome is still somewhat firm, it can usually be saved. Soak it in a bucket of room-temperature water for a few hours to rehydrate it, then pack it back into its box with a slightly more moisture-retentive material, or give it a light misting.
There is Mold on the Stems
A little bit of surface mold isn't usually a death sentence. It often happens where the stem was cut. Wipe the mold off with a dry cloth and increase the airflow in your storage area. As long as the rhizome itself remains firm and healthy, the plant will be just fine.
Summary of Canna Storage Success
Storing canna bulbs is one of the most rewarding "circular" gardening habits you can develop. It turns a one-season plant into a lifetime investment. By following these simple steps—waiting for the frost, curing the rhizomes, and keeping them in a cool, dark place—you ensure that your garden will always have that touch of the tropics.
At Longfield Gardens, we want your gardening experience to be as successful as it is enjoyable. Protecting your cannas over the winter is a small task that pays off in a big way when those first vibrant green shoots poke through the soil in the spring.
- Wait for the first frost to signal dormancy.
- Cure rhizomes for 1–3 days to prevent rot.
- Store in a medium like peat moss or wood shavings.
- Keep temperatures between 45°F and 55°F.
- Check monthly to ensure they aren't too wet or too dry.
The effort you put into storing your canna rhizomes today is the secret to a spectacular, high-impact garden next summer. It’s an easy win for any gardener.
FAQ
Can I store canna rhizomes in the refrigerator?
While a refrigerator is cool and dark, it is generally not recommended for canna storage. Most refrigerators are kept around 35–38°F, which is slightly too cold for cannas and can cause tissue damage over several months. Additionally, the low humidity in a fridge can cause the rhizomes to dry out and shrivel very quickly.
What happens if I forget to dig my cannas before a hard freeze?
If the ground hasn't frozen solid, your rhizomes are likely still safe. A hard freeze that kills the foliage won't necessarily kill the underground rhizome immediately. However, you should dig them as soon as possible after the freeze, as the decaying foliage can eventually lead to rot in the crown of the plant.
Do I need to treat my rhizomes with fungicide before storing?
For the average home gardener, a fungicide treatment is usually not necessary if the rhizomes are properly cured and kept at the right moisture level. However, if you have had recurring issues with rot in the past, you can lightly dust the cut ends of the rhizomes with sulfur powder or a general-purpose garden fungicide as an extra precaution.
Should I wash all the dirt off the rhizomes before storing?
It is a good idea to remove most of the soil, as garden soil can hold excessive moisture and pathogens that encourage rot. You don't need them to be perfectly "scrubbed" clean, but removing the bulk of the dirt allows you to inspect the rhizomes for health and ensures they dry out properly during the curing phase.