Table of Contents
- Introduction
- Understanding Canna Hardiness
- When to Begin the Winterizing Process
- Step 1: Cutting Back the Foliage
- Step 2: Digging Up the Rhizomes
- Step 3: Cleaning and Inspecting
- Step 4: Curing the Rhizomes
- Step 5: Packing for Winter Storage
- Step 6: Finding the Right Storage Spot
- Monitoring Your Cannas During Winter
- Dividing Cannas: Fall vs. Spring
- Winterizing Container-Grown Cannas
- Preparing for Spring Replanting
- Safety and Toxicity Notes
- Troubleshooting Common Storage Issues
- Conclusion
- FAQ
Introduction
There is nothing quite like the bold, tropical flair of cannas to make a summer garden feel like a private paradise. Their oversized foliage and brilliant blooms provide a dramatic backdrop that lasts from the heat of July until the very first touch of autumn chill. If you have enjoyed their vibrant presence this season, you will be happy to know that these plants are easy to keep for next year.
At Longfield Gardens, we want to help you enjoy your favorite plants season after season. While cannas are tropical by nature, they are also incredibly resilient if you follow a few simple steps. Winterizing canna bulbs—which are technically called rhizomes—is a straightforward process that allows you to save your favorite varieties and even increase your collection over time.
This guide is designed for home gardeners who want a reliable, step-by-step method for storing cannas through the winter months. We will cover when to dig them up, how to prepare them for storage, and the best ways to ensure they stay healthy until spring. By taking a little time now, you can ensure your garden returns to its full tropical glory as soon as the warm weather returns. If you prefer the tallest statements, browse our Tall Cannas collection.
Understanding Canna Hardiness
The first step in knowing how to winterize canna bulbs is understanding the environment your plants live in. Cannas are native to the tropics and subtropics, which means they are built for warmth rather than frost. In the United States, their ability to stay in the ground all year depends entirely on your USDA hardiness zone map.
In zones 8 through 10, cannas are generally considered hardy perennials. In these warmer climates, the ground rarely freezes deep enough to damage the fleshy rhizomes. Gardeners in these areas can often leave their plants in the soil, perhaps adding a thick layer of mulch for extra protection during an unusually cold snap.
However, for those of us in zones 7 and colder, the winter freeze will eventually reach the rhizomes and cause them to rot. In these regions, we treat cannas as "tender perennials." This means we dig them up in the fall, store them in a frost-free environment, and replant them once the soil warms up in the spring. This cycle of lifting and storing is the secret to enjoying the same beautiful varieties, like 'Wyoming' or City of Portland, for many years.
When to Begin the Winterizing Process
Timing is everything when it comes to lifting cannas. You want to give the plants as much time as possible to store energy in their rhizomes, but you must move before the ground freezes solid. The most reliable signal comes from the plants themselves.
The First Frost Signal
The best time to dig up your canna bulbs is shortly after the first light frost of the season. You will notice that the lush green or bronze leaves suddenly turn black or brown and become limp. This is a natural signal that the plant has entered dormancy.
While the foliage is damaged by a light frost, the rhizomes underground are still perfectly safe. In fact, that first touch of cold helps tell the plant to move all its remaining nutrients down into the "bulb" for winter storage. If you live in an area where the first frost is very late, you can also choose to dig them up in late October or early November, even if the leaves are still green.
Monitoring Soil Conditions
Try to choose a dry, sunny day for your digging. When the soil is relatively dry, it is much easier to shake off the excess dirt without damaging the tender skin of the rhizomes. If the weather forecast predicts a week of heavy rain followed by a deep freeze, it is better to get them out of the ground early rather than waiting for the perfect frost signal.
Key Takeaway: Wait for the first light frost to blacken the foliage before digging. This ensures the plant has finished its growing cycle and is ready for a period of rest.
Step 1: Cutting Back the Foliage
Once the leaves have turned brown and the plant looks ready for a nap, your first task is to clear away the top growth. This makes the digging process much easier and helps you see exactly where the base of the plant is located.
Using a sharp pair of garden shears or a lopper, cut the stalks down to about 4 to 6 inches above the soil line. Leaving a few inches of the stem provides a convenient "handle" for moving the clumps later. It also helps you keep track of which way is up when you eventually pack them away.
Discard the old foliage in your compost pile, provided the plants were healthy throughout the season. If you noticed any signs of pests or disease during the summer, it is better to dispose of the foliage in the trash to prevent those issues from returning next year.
Step 2: Digging Up the Rhizomes
Digging up cannas is a rewarding task because you will often find that the single rhizome you planted in the spring has grown into a large, heavy clump of several new "bulbs." To keep these new starts healthy, you need to be gentle during the extraction.
Using the Right Tools
A garden fork is often the best tool for this job. Unlike a flat shovel, the tines of a fork are less likely to slice through the fleshy rhizomes. If you only have a shovel, just be sure to give the plant a wide berth.
The Extraction Process
Start digging about 10 to 12 inches away from the base of the stems. You want to go deep enough to get under the entire root mass. Slowly work your way around the plant, lifting upward from different angles to loosen the soil.
Once the soil is loose, use the stems as a handle to gently lift the entire clump out of the hole. Do not be surprised by the weight; a healthy canna clump can be quite heavy and full of soil. Gently shake the clump or use your hands to brush away the large chunks of dirt.
Step 3: Cleaning and Inspecting
Once the clumps are out of the ground, you have a choice: to wash or not to wash. Both methods can work, but the goal is the same—removing enough soil so you can inspect the health of the rhizomes.
To Wash or Not to Wash?
In many cases, simply brushing off the loose soil with your hands is enough. If your soil is heavy clay and sticks to every crevice, you can use a gentle spray from a garden hose to rinse the rhizomes clean.
If you do wash them, it is very important that you allow them to dry completely before moving to the next step. Moisture trapped against the skin of a bulb in storage is the primary cause of rot.
The Health Inspection
As you clean, look for any soft spots, signs of mold, or damage from insects. Healthy canna rhizomes should feel firm, similar to a fresh potato. If you find a piece that is mushy or looks shriveled and hollow, discard it now. It is better to store only the healthiest specimens to ensure a successful start next spring.
Step 4: Curing the Rhizomes
One of the most overlooked steps in how to winterize canna bulbs is the curing process. Curing is simply a fancy word for letting the rhizomes air-dry in a protected spot for a few days.
Why Curing Matters
Curing allows the outer "skin" of the rhizome to toughen up. This acts as a natural barrier against dehydration and fungal issues during the long winter months. It also ensures that any remaining moisture on the surface evaporates.
How to Cure
Place your cleaned rhizomes in a single layer on a piece of cardboard, a wooden crate, or a screen. Keep them in a dry, well-ventilated area that is out of direct sunlight and safe from frost. A garage, garden shed, or a covered porch works perfectly.
Leave them to dry for three to seven days. By the end of this period, any remaining soil should be dry and crumbly, and the cut ends of the stems should look calloused and dry.
What to do next:
- Cut stalks to 4-6 inches.
- Dig carefully with a garden fork.
- Brush off loose soil and inspect for firmness.
- Air-dry (cure) in a protected spot for about a week.
Step 5: Packing for Winter Storage
After curing, your cannas are ready to go into their winter home. The goal of storage is to keep the rhizomes dormant: they should stay cool enough that they do not sprout, but warm enough that they do not freeze. They also need just enough humidity so they do not shrivel up completely.
Choosing a Storage Medium
Storing rhizomes in a "medium" helps regulate moisture. Popular options include:
- Peat Moss: Excellent for holding just a tiny bit of moisture while remaining airy.
- Vermiculite or Perlite: Sterile options that provide great insulation.
- Wood Shavings: Often used for pet bedding, these are inexpensive and effective.
- Newspaper: You can wrap individual rhizomes in several layers of dry newspaper.
The Container
Use a container that allows for some air circulation. Cardboard boxes, paper bags, or plastic bins with holes drilled in the sides are all good choices. Avoid airtight plastic containers, as these trap moisture and lead to rot.
The Packing Method
Place a layer of your chosen medium in the bottom of the box. Lay the rhizomes on top, making sure they do not touch each other. If one happens to develop rot, keeping them separated prevents the problem from spreading to the whole batch. Cover them with more medium and repeat the layers until the box is full.
Step 6: Finding the Right Storage Spot
The ideal storage location is a dark, cool space where temperatures stay consistently between 40°F and 50°F. If the temperature stays above 55°F, the cannas may think spring has arrived and begin to sprout prematurely. If it drops below freezing, the rhizomes will turn to mush.
Common storage locations include:
- An unheated basement
- A cool closet
- An insulated crawl space
- A frost-free garage
Avoid spots near furnaces, water heaters, or large windows where temperatures can fluctuate wildly.
Monitoring Your Cannas During Winter
Winterizing is not a "set it and forget it" task. To ensure the highest survival rate, we recommend checking on your stored bulbs once a month. This small effort allows you to catch any minor issues before they become big problems.
Checking for Rot
During your monthly check-in, feel a few of the rhizomes. If you find one that has become soft or mushy, remove it immediately. If the rot is only on one small end, you can sometimes cut that portion off, let the piece dry, and put the healthy part back in storage.
Checking for Dehydration
If the rhizomes feel very light and look extremely shriveled, they may be getting too dry. In this case, use a spray bottle to lightly mist the packing medium with a tiny amount of water. You don't want it to feel "wet," just slightly less bone-dry.
Dividing Cannas: Fall vs. Spring
Because cannas are so vigorous, you will likely find that your clumps have become quite large. Dividing them is the best way to get more plants for free. You can divide them either in the fall before you store them or in the spring before you plant them.
We often recommend waiting until spring to do the final division, and the How to Split Canna Lily Bulbs guide explains the process well. This is because the rhizomes are easier to handle once they have finished their dormant period, and you can clearly see where the new "eyes" (growth points) are located.
However, if your clumps are simply too large to fit into your storage boxes, you can certainly break them into smaller pieces in the fall. If you do this, make sure each piece has at least one or two "eyes"—these look like small, pointed bumps on the surface of the rhizome. Dust any fresh cuts with a little bit of sulfur powder or simply let them callous over for an extra day before packing them away.
Winterizing Container-Grown Cannas
If you grow your cannas in large pots on your patio, you have a convenient shortcut. You don't necessarily have to dig the rhizomes out of the soil.
Once the frost has hit the foliage, cut the stems back to the soil level as usual. Instead of digging, 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 in their containers. For compact options, the Short Cannas collection is worth a look.
In the spring, you can pull the clump out of the pot, refresh the soil, divide the rhizomes if they have become too crowded, and start watering them again to wake them up.
Preparing for Spring Replanting
As winter begins to fade, you can start thinking about bringing your cannas back into the light. In most regions, cannas should be planted outdoors only after the danger of frost has passed and the soil has warmed to at least 60°F.
Waking Them Up Early
If you want to get a head start on the season, you can start them indoors about 4 to 6 weeks before the last frost date. Place the rhizomes in pots with some damp potting soil and put them in a warm, sunny window. By the time the weather is right for outdoor planting, you will already have several inches of lush green growth.
Success in the Garden
When you are ready to plant, remember that cannas love sun and moisture. Choose a spot that gets at least 6 to 8 hours of direct sunlight. Plant the rhizomes about 4 to 5 inches deep with the "eyes" pointing upward. Space them about 1 to 2 feet apart to give them plenty of room to expand throughout the summer.
Spring Preparation Steps:
- Check rhizomes for firmness in late March.
- Optional: Start indoors in pots 4-6 weeks before the last frost.
- Plant outdoors once soil is 60°F and frost danger is gone.
- Choose a sunny spot with rich, well-draining soil.
Safety and Toxicity Notes
While gardening is a safe and joyful activity, it is always wise to keep a few safety points in mind. Canna rhizomes are generally considered non-toxic to humans and pets. In some cultures, certain types of canna are even grown as a food source for their starch.
However, many garden plants can cause digestive upset if ingested by curious pets or children. It is always a good practice to store your dormant bulbs in a place where they won't be mistaken for food or chewed on by pets. Additionally, when handling any bulbs or storage media like peat moss, wearing garden gloves can help protect your skin from irritation.
Troubleshooting Common Storage Issues
Even with the best care, you might encounter a few hiccups during the winterizing process. Here is how to handle the most common situations with a positive approach.
Rhizomes Sprouting Too Early
If you notice green shoots appearing in February, your storage area is likely a bit too warm. Move the box to a cooler spot. If the sprouts are small, they won't hurt the plant; just be careful not to break them off when you finally go to plant them.
White Mold on Surface
If you see a light dusting of white mold on the rhizomes, it usually means there is a bit too much moisture and not enough air circulation. Remove the affected bulbs, wipe them off, and let them air-dry for a day. Move them to a box with more ventilation or use a drier packing medium.
Shriveled Rhizomes
If the rhizomes look like raisins, they are losing too much moisture. A very light misting of the packing material (not the bulb itself) can help. Remember, the goal is "barely damp," not wet.
Conclusion
Winterizing canna bulbs is a simple but rewarding part of the gardening cycle. By following these steps, you are protecting your investment and ensuring that your garden will be filled with tropical color year after year. At Longfield Gardens, we believe that the extra effort taken in the fall makes the return of spring even more exciting, and our 100% Quality Guarantee helps back that promise.
Caring for these plants allows you to watch them grow and multiply, giving you more to share with friends and neighbors or more to fill your own landscape. Whether you are saving a classic 'Red King Humbert' or a striking 'Yellow King Humbert', the process is an easy win for any gardener. If you want a ready-made mix, the Canna Assorted Collection is another simple option.
- Wait for the first frost to signal dormancy.
- Cure the rhizomes thoroughly to prevent rot.
- Store in a cool, dark, frost-free location.
- Check monthly to ensure they stay healthy.
"Saving your canna bulbs is a wonderful way to connect with the seasons. It turns a one-summer plant into a lifelong garden companion."
We look forward to seeing your garden thrive! For more tips on growing and caring for your favorite summer blooms, explore our All About Cannas.
FAQ
Can I leave my cannas in the ground if I use a lot of mulch?
In USDA zones 8 and warmer, a thick layer of mulch (about 6 inches) is usually enough to protect canna rhizomes through the winter. In zone 7, it is a bit of a gamble; in a mild winter they may survive, but in a harsh winter they will likely rot. For gardeners in zones 6 and colder, digging them up is the only way to ensure they survive.
Do I have to wait for a frost to dig up my canna bulbs?
You do not strictly have to wait for a frost, but it is highly recommended. The frost tells the plant to stop growing and move its energy into the rhizome. If you must dig them up early due to travel or scheduling, simply cut the foliage back and follow the same curing and storage steps.
What happens if I don't clean the dirt off the rhizomes?
If your soil is sandy and dry, leaving a little bit on won't hurt. However, if the soil is damp and heavy, it can trap moisture against the skin of the rhizome and cause it to rot in storage. Taking the time to brush off most of the soil and letting the rhizomes "cure" is the best way to prevent winter losses.
How many "eyes" should each division have?
For the best results, each piece of canna rhizome should have at least one to three visible "eyes" or growth points. These look like small, pointed nubs on the surface. Each eye will eventually become a new stalk, so having multiple eyes ensures a fuller, more vigorous plant in its first season back in the garden.