Table of Contents
- Introduction
- Why We Store Canna Rhizomes
- Identifying Your USDA Hardiness Zone
- When to Dig Up Canna Bulbs
- Step-By-Step: Harvesting Your Cannas
- Cleaning and Preparing for Storage
- The Curing Process
- Choosing Your Storage Medium
- The Ideal Storage Environment
- Winter Check-Ups
- Storing Cannas Grown in Containers
- Preparing for Spring Replanting
- Simple Troubleshooting
- Growing with Confidence
- Conclusion
- FAQ
Introduction
There is nothing quite like the lush, tropical energy that cannas bring to a summer garden. With their broad, banana-like leaves and vibrant blossoms in shades of red, orange, and yellow, they transform any backyard into a vacation-worthy retreat. At Longfield Gardens, we love how these easy-to-grow plants provide structure and height while thriving in the heat of July and August.
While cannas are incredibly resilient during the growing season, they are tender perennials that cannot survive freezing soil. If you live in a region with cold winters, taking a little time to store your canna rhizomes—often called "bulbs"—is a rewarding way to ensure your favorite varieties return even bigger and better next year. It is a simple process that feels like putting your garden to bed for a well-deserved rest.
This guide will walk you through the straightforward steps of harvesting, curing, and storing your cannas. Whether you are a beginner or a seasoned gardener, we want to help you feel confident in preserving these tropical beauties. By following a few basic rules for winter care, you can enjoy your canna collection for many seasons to come.
Properly storing your canna rhizomes allows you to protect your investment and enjoy a more beautiful, established garden every spring.
Why We Store Canna Rhizomes
To understand why we store cannas, it helps to know where they come from. Cannas are native to tropical and subtropical regions of the Americas. In their natural habitat, they never experience a hard freeze. Instead, they grow year-round or take a brief rest during dry spells.
The "bulb" of a canna is actually a rhizome. A rhizome is a thick, fleshy underground stem that stores energy and nutrients for the plant. Think of it as a battery that powers the next season’s growth. When the temperature drops below freezing, the water inside the cells of the rhizome can freeze and expand. This causes the cell walls to burst, leading to mushy, rotten plants that cannot regrow in the spring.
For most of the United States, winter temperatures are too low for these tropical structures to survive in the ground. By digging them up and moving them to a frost-free environment, we mimic their natural resting period. This ensures the "battery" stays charged and ready to sprout as soon as the soil warms up again in late spring.
Identifying Your USDA Hardiness Zone
Before you get your shovel ready, it is helpful to know your USDA hardiness zone. This map is the standard used by gardeners to determine which plants can survive the winter in a specific location.
- Zones 8 to 10: In these warmer regions, cannas are usually fine to stay in the ground year-round. You can simply cut the foliage back after it fades and perhaps add a light layer of mulch for protection.
- Zone 7: This is the "swing" zone. In mild winters, cannas may survive in the ground with a heavy layer of mulch (6–8 inches of straw or leaves). However, a particularly cold winter can still be a risk. Many gardeners in Zone 7 choose to dig up their favorite varieties just to be safe.
- Zones 3 to 6: In these colder northern climates, the ground freezes deep enough to reach the rhizomes. In these zones, digging and storing cannas is essential if you want to keep them for next year.
Key Takeaway: Storing canna rhizomes is a simple way to protect tropical plants from freezing temperatures, ensuring they have the energy to bloom again next summer.
When to Dig Up Canna Bulbs
Timing is one of the most important parts of winter storage. You want to give your cannas as much time as possible to store energy, but you must act before the ground freezes solid.
The First Frost Signal
The best time to dig up your cannas is shortly after the first light frost of autumn. You will know this has happened when the lush green foliage suddenly turns black or dark brown. While it might look like the plant is "ruined," this is actually a helpful signal from nature.
A light frost kills the top growth but doesn't penetrate the soil. This tells the plant to stop sending energy to the leaves and start focusing entirely on the rhizomes. We recommend waiting a few days after this first frost to let the nutrients finish moving down into the "bulb."
Avoiding the Deep Freeze
While a light frost is helpful, a "hard freeze" (where temperatures stay well below freezing for several hours or days) can be dangerous. If the ground freezes several inches deep, the rhizomes can be damaged. Always check your local weather forecast in late October or November. If a significant cold snap is predicted, it is better to dig them a little early than to wait too long.
What to Do Next
- Watch for the first frost to turn foliage brown.
- Check the 10-day forecast for any deep-freeze warnings.
- Gather your tools: a garden fork or shovel, pruning shears, and some labels.
Step-By-Step: Harvesting Your Cannas
Harvesting cannas is an easy afternoon project. The goal is to lift the rhizomes out of the ground with as little damage as possible.
1. Cut Back the Foliage
Before you start digging, use a pair of sharp pruning shears or a garden knife to cut the stalks down. We suggest leaving about 2 to 4 inches of the stem attached to the rhizome. This gives you a "handle" to grab and helps you keep track of which side is up. Removing the bulky leaves also makes it much easier to see what you are doing.
2. Loosen the Soil
Cannas often grow in large clumps, and the rhizomes can spread out further than you might expect. To avoid accidentally slicing through a rhizome, start digging about 6 to 12 inches away from the base of the stems.
A garden fork is often better than a shovel for this job, as the tines can slide around the rhizomes rather than cutting through them. Gently work the fork around the entire perimeter of the plant, lifting upward to loosen the soil.
3. Lift the Clump
Once the soil is loose, reach under the clump and lift it out of the hole. If you have healthy, happy cannas, you might find that a single rhizome planted in spring has turned into a massive, heavy cluster. Don't worry about separating them just yet; it is often safer to store them in larger clumps and divide them in the spring.
4. Remove Excess Dirt
Gently shake the clump to remove large chunks of soil. You can use your hands to brush away loose dirt, but avoid being too aggressive. The "skin" of the rhizome is somewhat tender when it first comes out of the moist ground.
Key Takeaway: Dig several inches away from the stalks to avoid damaging the fleshy rhizomes. Leaving a few inches of stem makes handling and labeling much easier.
Cleaning and Preparing for Storage
Once your cannas are out of the ground, they need a little bit of preparation before they go into their winter containers.
To Wash or Not to Wash?
There are two schools of thought on washing canna rhizomes. Some gardeners prefer to use a garden hose to wash away all the soil. This makes it easier to spot any signs of rot or insect damage.
Other gardeners prefer to let the soil dry and then gently brush it off. Either method works well. If you do choose to wash them with water, make sure you allow them to dry completely afterward. Excess moisture is the primary enemy of a stored bulb, as it can lead to mold and rot.
Inspecting for Health
Take a moment to look over your harvest. A healthy canna rhizome should feel firm, similar to a fresh potato. If you find any soft, mushy, or blackened spots, trim those parts away with a clean knife. If a whole section is rotten, it is best to discard it so the rot doesn't spread to your healthy plants.
Labeling Your Varieties
If you grow several different types of cannas—such as a tall 'Wyoming' with dark foliage and a shorter, yellow-flowered variety—now is the time to label them. It is very easy to forget which is which once the leaves are gone! You can write the name directly on the dried stem with a permanent marker or tie a waterproof tag around the base.
The Curing Process
Curing is a simple but vital step that many beginners overlook. Curing is the process of letting the outer skin of the rhizome dry and toughen up. This creates a natural protective barrier that helps the plant resist disease and prevents it from drying out too much during the winter.
How to Cure Your Cannas
Place your cleaned rhizomes in a single layer on a tray, a piece of cardboard, or a screen. Keep them in a dry, well-ventilated area that is protected from frost and direct sunlight. A garage, garden shed, or a covered porch works perfectly.
Let the rhizomes sit for about 7 to 10 days. During this time, the cut ends of the stems will dry out and "callous" over. This callousing is exactly what we want. Once the exterior feels dry and the skin seems slightly tougher, they are ready for their final storage.
What to Do Next
- Place rhizomes in a single layer for airflow.
- Ensure the curing area is dry and out of the sun.
- Wait about a week for the skin to toughen.
Choosing Your Storage Medium
You cannot simply toss canna rhizomes into a plastic bin and close the lid. They need a storage environment that balances two things: they must stay dry enough to avoid rot, but they must stay "alive" enough that they don't turn into shriveled, hard husks.
To achieve this balance, we use a storage medium. Here are the most effective options:
Peat Moss or Vermiculite
Dry peat moss or vermiculite are excellent choices. They are lightweight and do a great job of absorbing excess moisture while still providing a bit of insulation. Simply fill a box with a layer of the material, nestle the rhizomes inside so they aren't touching each other, and cover them with more peat or vermiculite.
Wood Shavings
The type of wood shavings sold for pet bedding (like pine or cedar) is another popular option. These shavings allow for excellent airflow, which is the best defense against mold.
Newspaper and Cardboard
If you prefer a simpler approach, you can wrap individual rhizomes in several layers of dry newspaper. Place the wrapped bundles inside a cardboard box. The cardboard and paper are "breathable," which helps regulate moisture naturally.
Avoid Plastic
We do not recommend using airtight plastic bins or sealed plastic bags. These trap moisture inside, which almost always leads to rot. If you must use a plastic tote, leave the lid off or drill several large holes in the sides to allow for air circulation.
Key Takeaway: The goal of storage is "breathable protection." Use materials like peat moss, wood shavings, or newspaper to keep the rhizomes cushioned and dry.
The Ideal Storage Environment
Where you put your boxes of cannas is just as important as how you pack them. You are looking for a "Goldilocks" environment: not too hot, not too cold.
Temperature
The ideal temperature for storing canna rhizomes is between 40°F and 50°F.
- Too Cold: If the temperature drops below 35°F, the rhizomes may freeze and die.
- Too Warm: If the temperature stays above 55°F or 60°F, the plants may think it is spring and start to sprout prematurely. This uses up their stored energy too early.
Location
Common successful storage spots include:
- An unheated (but attached) garage.
- A cool basement or cellar.
- A crawl space.
- A closet in a cool part of the house.
Darkness and Airflow
Keep the storage containers in the dark. Light can also trigger the plant to start growing before it should. Additionally, ensure there is some air movement in the room. Stagnant, damp air is a recipe for mold growth.
Winter Check-Ups
Even though the cannas are resting, it is a good idea for us to check on them once a month. This small effort can save your entire collection if a problem starts to develop.
Checking for Rot
When you open your storage boxes, look for any signs of mold or soft spots. If you catch a bit of rot early, you can often cut it away, let the healthy part of the rhizome dry out for a day, and then put it back into storage. If a rhizome is completely mushy, remove it immediately so it doesn't infect the others.
Checking for Dehydration
On the flip side, sometimes the air in our homes can be very dry during the winter. If the rhizomes start to look extremely shriveled or feel light and hollow, they may be dehydrating.
If this happens, you can use a spray bottle to very lightly mist the storage medium (the peat moss or shavings) with water. You don't want it to be wet—just a tiny bit of humidity is enough to keep the rhizomes "plump."
What to Do Next
- Set a monthly reminder on your calendar to check your bulbs.
- Remove any soft or molding rhizomes immediately.
- Lightly mist the packing material only if the rhizomes appear severely shriveled.
Storing Cannas Grown in Containers
If you grow your cannas in large pots or decorative containers, you have a shortcut! Container-grown cannas are often even easier to overwinter.
After the first frost kills the foliage, cut the stems down to the soil level as usual. Instead of digging the rhizomes out, you can simply move the entire pot into a cool, frost-free location like a basement or garage.
Stop watering the pot entirely. The soil will dry out, and the cannas will go dormant right there in the container. 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 couple of years, however, 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.
Preparing for Spring Replanting
The excitement of a new gardening season begins when you see those first signs of spring. For cannas, this is usually after the danger of frost has passed and the soil has warmed to at least 60°F.
Inspecting Your Harvest
When you pull your rhizomes out of storage in the spring, give them a final inspection. They should still be firm. You might even see small "eyes" (growing points) starting to swell or turn pink. This is a great sign!
Dividing Your Rhizomes
This is the best time to divide your canna clumps. You can break or cut the large clusters into smaller sections. Each section should have at least one to three healthy "eyes." If you use a knife to divide them, let the cut ends dry for a day before planting to prevent soil-borne diseases from entering the fresh cuts.
Starting Early Indoors
If you live in a very cold climate with a short growing season, you can give your cannas a head start. About 4 to 6 weeks before the last frost date, plant the rhizomes in pots with potting soil and place them in a sunny window or under grow lights. By the time the weather is warm enough to move them outside, you will already have several inches of lush growth.
Simple Troubleshooting
Gardening is a learning process, and every winter is a little different. If things don't go perfectly, don't be discouraged. Even expert gardeners occasionally lose a few bulbs.
- If the rhizomes rotted: Next year, ensure they are 100% dry before packing them away. You might also try a more breathable storage medium like wood shavings instead of peat moss.
- If the rhizomes shriveled up: They likely got too dry. Try storing them in a slightly cooler spot or in a larger volume of peat moss to help hold in their natural moisture.
- If they sprouted in January: The storage area was probably too warm. Move the boxes to a cooler spot, like an outer wall of the basement or a lower shelf in the garage.
Growing with Confidence
At Longfield Gardens, we believe that gardening should be a source of joy, not stress. Storing cannas is one of those traditional gardening tasks that connects us to the cycle of the seasons. There is a special kind of satisfaction in "rescuing" your plants from the winter cold and seeing them emerge with vigor the following year.
By getting the basics right—timing the harvest with the frost, curing the rhizomes properly, and providing a cool, breathable home for the winter—you are setting yourself up for a spectacular summer display. We stand behind the quality of our plants, and we want to see yours thrive year after year.
As you pack your cannas away this fall, you can already start dreaming of next year’s garden. Perhaps you’ll add a few new colors to your collection or use your newly divided rhizomes to create a tropical border in a different part of your yard. Whatever you choose, the effort you put in now will be rewarded with a taller, brighter, and more beautiful garden next summer.
Key Takeaway: Successful winter storage relies on the "big three": proper curing, the right storage medium, and a cool, frost-free location.
Conclusion
Storing canna bulbs over winter is a simple, effective way to enjoy these magnificent tropical plants year after year. By following the natural cues of the first frost and providing a stable, cool environment during the dormant months, you ensure your garden remains vibrant and lush. It is a rewarding practice that saves money and allows your plants to grow larger and more impressive with each passing season.
- Wait for the first frost to signal dormancy before digging.
- Cure the rhizomes for a week to toughen their protective skin.
- Store in a breathable medium at temperatures between 40°F and 50°F.
- Check monthly for moisture balance and remove any signs of rot.
We are here to support your gardening journey every step of the way. With a little bit of winter care, your cannas will be ready to bring that tropical flair back to your landscape as soon as the warm weather returns.
"The secret to a beautiful spring garden often lies in the thoughtful care we provide during the winter months."
FAQ
Do I have to wait for a frost before digging up my cannas?
While it isn't strictly mandatory, waiting for a light frost is highly recommended. The frost kills the foliage and sends a clear signal to the plant to move its energy and nutrients down into the rhizome for winter storage. This "natural shutdown" helps the rhizome stay healthy and vigorous throughout its dormancy.
Can I store canna rhizomes in the refrigerator?
While a refrigerator is cool, it is generally not recommended for storing cannas. Refrigerators are often too cold (usually around 35°F-38°F) and the air inside is very dehydrating. Additionally, some fruits and vegetables release ethylene gas, which can damage or kill the dormant flower buds inside the rhizome. A cool basement or garage is a much better choice.
Should I divide my canna rhizomes in the fall or the spring?
It is usually best to wait until spring to divide your cannas. Storing them in larger clumps helps protect the inner sections from drying out. In the spring, it is also much easier to see the "eyes" or growing points, which ensures that every piece you cut has the ability to grow into a new plant.
What should I do if my stored cannas start growing in the middle of winter?
If you see sprouts appearing, your storage area is likely too warm. Move the containers to a cooler location immediately to slow down the growth. If the sprouts are small, you can leave them alone; however, if they grow several inches long, you may need to pot them up and treat them as houseplants until it is time to move them outdoors.