How to Winter Over Canna Bulbs for Next Year

Table of Contents

1. Introduction
2. Understanding Canna Rhizomes and Dormancy
3. When to Dig Canna Bulbs
4. Tools and Materials for Wintering Over
5. Step-by-Step Guide to Digging Canna Rhizomes
6. Cleaning and Curing for Success
7. The Best Ways to Store Canna Rhizomes
8. Monitoring Your Bulbs During Winter
9. Wintering Over Container-Grown Cannas
10. Getting Ready for Spring Planting
11. Conclusion
12. FAQ

Introduction

Canna lilies bring a bold, tropical flair to the summer landscape with their oversized leaves and vibrant, jewel-toned flowers. For a closer look at the taller options, browse our Tall Cannas collection. The sight of these tall, architectural plants blooming in late August is one of the greatest rewards for any gardener. Because they thrive in the heat, they keep the garden looking lush when other plants might begin to fade. At Longfield Gardens, we want to help you enjoy these spectacular plants year after year.

If you live in a region where the ground freezes, these tropical beauties require a little extra care to survive the winter. While they are hardy in warmer climates, gardeners in most of the United States need to bring them indoors. This process is known as "wintering over." It is a simple and rewarding way to preserve your favorite varieties and even increase your plant collection for the following season. If you want to get a head start on spring, our Starting Canna Lily Bulbs Indoors guide covers the basics.

This guide will walk you through the entire process of harvesting and storing your canna rhizomes. We will cover the best timing for digging, how to clean and cure the roots, and the ideal storage conditions to ensure they stay healthy until spring. Whether you are a beginner or an experienced gardener, these steps will help you successfully save your cannas for another year of beauty.

Saving your canna rhizomes is a practical way to build a sustainable and stunning garden.

Understanding Canna Rhizomes and Dormancy

To successfully winter over cannas, it is helpful to understand how they grow. Cannas grow from thick, fleshy underground stems called rhizomes. These rhizomes act as energy storage units for the plant. During the summer, the leaves capture sunlight and turn it into food, which is then stored in the rhizome. This stored energy allows the plant to sprout quickly and bloom vigorously once the weather warms up in the spring.

In their native tropical environments, cannas grow year-round. However, in most of the United States, they enter a period of dormancy when temperatures drop. Dormancy is a natural resting phase. The plant stops growing, the foliage dies back, and the rhizome waits for better conditions. When we talk about "wintering over," we are simply providing a safe, frost-free environment for the rhizomes to complete this resting phase. If you want to compare different heights and habits, the Medium Cannas collection is a helpful place to start.

Cannas are generally hardy in USDA zones 8 through 10. In these areas, the ground rarely freezes deep enough to reach the rhizomes. Gardeners in these zones can often leave their cannas in the ground with a thick layer of mulch for protection. However, if you live in zone 7 or colder, the winter temperatures will likely damage or kill the rhizomes if they are left outdoors. Digging them up ensures they stay dry and dormant rather than rotting in cold, wet soil.

When to Dig Canna Bulbs

Timing is everything when it comes to harvesting canna rhizomes. You want to give the plants as much time as possible to store energy, but you must get them out of the ground before the soil freezes solid. If you're not sure how your climate compares, check the USDA Hardiness Zone Map. The best signal to start the process comes from nature itself: the first frost.

The First Frost Rule

A light frost will typically turn canna leaves brown or black and cause them to wilt. This might look disappointing at first, but it is actually a helpful sign. This cold snap tells the plant that the growing season is over and it is time to move all its energy down into the rhizome. Once the foliage has been "zapped" by frost, you can begin digging.

If you live in an area where autumn is long and mild, you do not have to wait for a frost. You can dig them up once the weather stays consistently cool and the plants stop producing new flowers. However, waiting for that first frost is the most reliable way to ensure the rhizomes are fully mature and ready for storage.

Avoiding a Hard Freeze

While a light surface frost is beneficial, a hard freeze is a different story. A hard freeze occurs when temperatures drop well below freezing for several hours, causing the ground itself to begin to freeze. If the ground freezes several inches deep, it can damage the moisture-rich rhizomes. Aim to have your cannas out of the ground and in a protected area within a week or two of the first light frost.

Key Takeaway: Wait for the first light frost to turn the foliage brown. This signals the plant to go dormant and move its energy into the rhizomes for winter storage.

Tools and Materials for Wintering Over

Before you head out to the garden, gather the tools you will need. Having everything ready makes the process much smoother and prevents unnecessary trips back to the shed.

• Garden Fork or Shovel: A garden fork is often preferred because it is less likely to slice through the rhizomes. If you use a shovel, be sure to give the plant plenty of space.
• Pruning Shears or a Sharp Knife: You will need these to cut back the heavy stalks.
• Garden Hose: A gentle stream of water helps remove excess soil from the rhizomes.
• Labels and Markers: It is easy to forget which variety is which once the leaves are gone. Labeling is essential if you grow different colors like Canna Medium City of Portland.
• Storage Containers: Cardboard boxes, plastic bins with air holes, or paper bags all work well.
• Packing Material: Peat moss, vermiculite, wood shavings, or even crumpled newspaper will help regulate moisture during storage.

Step-by-Step Guide to Digging Canna Rhizomes

Digging up cannas is a straightforward task, but it requires a gentle touch. The rhizomes can be surprisingly large and somewhat brittle.

Step 1: Cut Back the Foliage

Once the frost has browned the leaves, use your pruning shears to cut the stalks back. Leave about 2 to 4 inches of the stem attached to the rhizome. This small "handle" makes the rhizomes easier to manage and helps you identify which side is up when it comes time to replant. Dispose of the old foliage in your compost pile or yard waste bin, provided the plants were healthy and disease-free.

Step 2: Loosen the Soil

Cannas can spread significantly underground during a single growing season. To avoid damaging the rhizomes, start digging at least 6 to 12 inches away from the base of the stalks. Insert your garden fork or shovel deep into the soil and gently pry upward. Work your way around the entire clump to loosen it from all sides.

Step 3: Lift the Clump

Once the soil is loose, lift the entire mass of rhizomes out of the ground. Do not pull on the stalks, as they can snap off. Instead, support the clump from underneath with your hands or your shovel. You will likely find a large, heavy mass of roots and soil. Shake off as much loose dirt as possible while you are still at the garden bed.

Step 4: Initial Cleaning

Use a garden hose to rinse away the remaining soil. You do not need to get them perfectly clean, but removing the bulk of the dirt allows you to inspect the rhizomes for any damage or signs of pests. A clean rhizome is also less likely to harbor soil-borne diseases during storage.

Cleaning and Curing for Success

After the rhizomes are out of the ground and rinsed, they need a short period of "curing." This is one of the most important steps in the process, yet it is often overlooked.

Why Curing Matters

Curing simply means letting the rhizomes air-dry for a few days before they go into long-term storage. This allows the outer skin to toughen up and any small nicks or cuts from the digging process to heal over. Properly cured rhizomes are much more resistant to rot and mold.

How to Cure Your Rhizomes

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, a shed, or a covered porch works perfectly. Let them sit for about 7 to 10 days. During this time, the "handle" of the stem you left behind will continue to dry out, and the rhizome itself will feel firm and dry to the touch.

Dividing (Optional)

While you are cleaning and curing, you might notice that your canna clumps have grown quite large. You can choose to divide them now or wait until spring. If you divide them in the fall, use a sharp, clean knife to cut the rhizomes into smaller pieces. Each piece should have at least two or three "eyes" (the small bumps or buds where new growth will emerge). If you make any cuts, let those pieces cure for an extra day or two to ensure the cut surfaces are dry. A striking tall variety like Canna Tall Pretoria is a good reminder to keep each variety clearly labeled.

What to do next:

• Rinse the rhizomes gently with a hose to remove soil.
• Place them in a dry, shaded spot with good airflow.
• Allow them to cure for 7 to 10 days until the skin feels tough.
• Check for any soft or damaged spots and trim them away before storage.

The Best Ways to Store Canna Rhizomes

Once the rhizomes are cured, they are ready for their winter nap. The goal of storage is to keep them dormant, cool, and just slightly moist so they do not shrivel up.

Choosing a Storage Medium

Canna rhizomes should not be stored completely "naked" in a box, as they can dry out too much. Instead, nestle them in a material that helps maintain a consistent environment. If you prefer smaller plants for pots or tight spaces, our Short Cannas collection is a useful option to keep in mind for spring.

• Peat Moss or Vermiculite: These are the most popular choices because they absorb excess moisture but keep the rhizomes from becoming bone-dry.
• Wood Shavings: Pine or cedar shavings (the kind sold for pet bedding) are excellent and provide good airflow.
• Newspaper: If you do not have other materials, wrapping individual rhizomes in several layers of newspaper can also work well.

Selecting a Container

Cardboard boxes are ideal because they "breathe," allowing for some air exchange. You can also use plastic bins, but you must leave the lid slightly ajar or drill several small holes in the sides to prevent moisture buildup. If the container is airtight, the rhizomes are likely to rot.

Finding the Right Location

The storage location must stay cool but never drop below freezing. The ideal temperature range is between 40°F and 50°F.

• Unheated Basements: These often provide the most stable temperatures.
• Attached Garages: These can work well, but be careful if the temperature drops significantly during a cold snap.
• Crawl Spaces: Many gardeners find success using the cool, dark area under a house.

Avoid storing your cannas near a furnace or water heater, as the heat will cause them to dry out or wake up too early.

Monitoring Your Bulbs During Winter

Wintering over cannas is not a "set it and forget it" task. It is a good idea to check on your stored rhizomes about once a month. This small effort can save your entire collection.

Checking for Rot

During your monthly inspection, look for any rhizomes that feel soft, mushy, or have a foul odor. If you find a spot of rot, you can often save the rest of the rhizome by cutting away the damaged portion with a clean knife. If a rhizome is completely rotted, discard it immediately so the mold does not spread to its neighbors.

Preventing Desiccation

On the other hand, if the rhizomes look very shriveled or feel extremely light, they may be drying out too much. If this happens, use a spray bottle to lightly mist the storage medium (the peat moss or shavings) with water. Do not soak the rhizomes; you just want to add a tiny bit of humidity back into the box.

Managing Early Growth

Sometimes, if the storage area is a bit too warm, cannas may begin to sprout pale green tips in late winter. If this happens, try to move them to a slightly cooler spot to slow down the growth. A little bit of early sprouting is usually fine, but you want to keep it to a minimum until it is time to plant.

Key Takeaway: Inspect your stored rhizomes monthly. Remove any that show signs of rot and lightly mist the storage material if the rhizomes appear overly shriveled.

Wintering Over Container-Grown Cannas

If you grow your cannas in pots, the process is even easier. You have two main options for wintering them over. If you plan to refresh your summer display next year, a bulk option like Canna Assorted Mix - Bulk Offer can help you rebuild quickly.

Option 1: The "Dormant Pot" Method

After the first frost, cut the foliage back to the soil level as you would with garden-grown cannas. Instead of digging the rhizomes out, 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 rhizomes will go dormant inside the container. In the spring, you can move the pot back outside, start watering, and the plants will regrow.

Option 2: Dig and Store

If you need the pots for winter displays or if the containers are too heavy to move, you can dig the rhizomes out of the pots just like you would from a garden bed. Follow the same cleaning, curing, and storage steps mentioned above. This is also a good time to refresh the potting soil, which can become depleted after a long summer of growth. For compact plants that work especially well this way, the Canna Short Orange Magic page is worth a look.

Getting Ready for Spring Planting

As the days get longer and the ground begins to thaw, it is time to start thinking about the upcoming garden season. At Longfield Gardens, we recommend waiting until the soil is warm and the danger of frost has passed before planting your cannas back into the garden. For a step-by-step planting refresher, see How to Plant Canna Lily Bulbs in the Ground.

Waking Up the Rhizomes

About 4 to 6 weeks before the last frost date in your area, you can bring your rhizomes out of storage. This is a great time to do a final inspection. Discard any that did not make it through the winter. Healthy rhizomes should feel firm and heavy for their size.

You can give your cannas a head start by "pre-starting" them indoors. If you want more container-specific guidance while you do that, the How to Grow Summer Bulbs in Containers article is a helpful companion. Plant the rhizomes in pots with moist potting soil and place them in a warm, sunny window or under grow lights. This gives them a few extra weeks of growth, which often results in earlier blooms once they move outdoors.

Hardening Off

If you have started your cannas indoors, remember to "harden them off" before planting them in the ground. This means gradually acclimating them to outdoor conditions over the course of a week. Start by putting them in a shaded, protected spot for a few hours a day, slowly increasing their time and exposure to sunlight.

Planting Depth and Spacing

When the soil has reached at least 60°F, plant your canna rhizomes about 4 to 6 inches deep. Place them horizontally in the soil with the "eyes" or sprouts facing upward. Space them about 1 to 2 feet apart, depending on the variety. Larger types need more room to show off their spectacular foliage.

Conclusion

Wintering over canna bulbs is one of the most satisfying ways to bridge the gap between gardening seasons. By following these simple steps—waiting for the frost, curing the rhizomes, and providing a cool, stable storage environment—you can ensure that your garden remains filled with tropical color year after year. It is a process that rewards a little bit of autumn effort with a lifetime of summer beauty.

At Longfield Gardens, we believe that gardening should be a rewarding and accessible experience for everyone. Our About Us & Our Guarantee page explains the standards behind every order. Saving your cannas is a great way to learn more about the lifecycle of your plants and to take pride in the continuity of your landscape. Whether you are storing a single favorite variety or a large collection, the steps remain the same.

• Wait for the first frost to signal dormancy.
• Cure the rhizomes for a week to toughen the skin.
• Store in a cool, dry place between 40°F and 50°F.
• Monitor monthly for moisture levels and health.

We hope this guide gives you the confidence to preserve your tropical treasures. With just a little care this winter, your cannas will be ready to transform your garden once again when the warm spring sun returns.

"Wintering over cannas is a simple cycle of care that turns a single summer bloom into a lifelong garden tradition."

FAQ

Can I store canna bulbs in plastic bags?

You can use plastic bags, but they must have several air holes punched in the sides to allow for ventilation. Without airflow, moisture can become trapped inside the bag, which often leads to mold or rot. A better option is a paper bag or a cardboard box, which naturally allows the rhizomes to breathe. If you have shipping questions as you plan ahead for spring, our Shipping Information page is a helpful reference.

Do I have to wash the dirt off the rhizomes?

While you do not need to scrub them clean, it is highly recommended to rinse off most of the soil. Removing the dirt makes it much easier to see if the rhizome is healthy or if there are pests hiding in the crevices. It also helps the curing process by ensuring the skin can dry evenly.

What if my canna rhizomes look shriveled in January?

A small amount of shriveling is normal as the rhizomes lose a bit of moisture during dormancy. However, if they look very thin or feel light, they are too dry. Lightly mist the peat moss or wood shavings in your storage container with water to increase the humidity, but be careful not to make the material wet.

Can I leave cannas in the ground if I live in Zone 7?

In Zone 7, cannas are on the edge of hardiness. In a mild winter, they may survive if they are planted in a protected spot and covered with 6 to 8 inches of mulch. However, during an unusually cold winter, they may freeze and rot. Digging them up is the only way to guarantee they will survive for the following year. If you want to double-check your local conditions, revisit the USDA Hardiness Zone Map.