Table of Contents
- Introduction
- Understanding Canna Rhizomes
- When to Dig Your Canna Rhizomes
- Preparing for the Dig
- Step-By-Step: Lifting Your Cannas
- Cleaning and Curing
- Packing for Winter Storage
- The Ideal Storage Environment
- Overwintering Cannas in Containers
- Winter Monitoring and Maintenance
- Preparing for Spring Replanting
- Simple Steps for Success
- Conclusion
- FAQ
Introduction
Canna lilies bring a bold, tropical energy to the garden that is hard to match. Their oversized, paddle-shaped leaves and vibrant, torch-like flowers make Cannas a favorite for adding height and drama to flower beds and patio containers. Watching a single small rhizome transform into a towering, lush plant over one summer is one of the most rewarding experiences a gardener can have.
At Longfield Gardens, we believe that gardening should be a source of joy rather than a cycle of starting over every spring. While cannas are tropical plants that thrive in the heat, you do not have to buy new ones every year. Saving your favorite varieties is a simple, cost-effective way to expand your garden, and the Canna Assorted Collection is an easy way to bring home a mix of colors.
This guide will show you exactly how to lift, clean, and store your canna rhizomes so they stay healthy through the cold months. Whether you are a beginner or an experienced gardener, you will find that overwintering these plants is a straightforward task that fits easily into your autumn garden cleanup. For a broader overview of planting, growing, and overwintering, see All About Cannas. By following a few basic steps, you can preserve these beautiful plants and enjoy an even bigger floral display next year.
Understanding Canna Rhizomes
Before we jump into the steps of saving your plants, it is helpful to understand what you are working with. Although many people refer to them as bulbs, cannas actually grow from rhizomes. A rhizome is a thick, fleshy underground stem that stores energy and nutrients for the plant.
During the summer, the leaves of the canna act like solar panels. They soak up the sun and convert that energy into carbohydrates, which are then pumped down into the rhizome. This stored energy is what allows the plant to sprout vigorously when the warm weather returns.
In USDA hardiness zones 8 through 11, cannas can usually stay in the ground year-round. However, for those of us in zone 7 and colder, the freezing winter temperatures will turn these fleshy rhizomes into mush if they are left in the soil. Saving them is simply a matter of moving that "energy pantry" to a place where it will stay cool but never freeze. Our Hardiness Zone Map can help you check your zone.
Key Takeaway: Wait for the first light frost to blacken the leaves before digging. This ensures the rhizome has stored the maximum amount of energy for next year's growth.
When to Dig Your Canna Rhizomes
Timing is one of the most important parts of successfully saving cannas. You want to give the plants as much time as possible to store energy, but you must get them out of the ground before a deep, hard freeze reaches the rhizomes. For a broader look at overwintering tender bulbs and tubers, see Winter Storage for Tender Bulbs and Tubers.
The best time to start the process is after the first light frost of the season. You will know it has happened when the lush green or bronze foliage turns black or dark brown overnight. This might look like a sad moment for your garden, but it is actually a helpful signal. The frost tells the plant that the growing season is over and it is time to go dormant.
Once the foliage has been "zapped" by frost, the plant stops active growth and moves all its remaining resources into the rhizome. You generally have a window of a few days to a week after this first frost to get the rhizomes out of the ground. If your area doesn't experience frost until very late in the year, you can simply wait until the foliage starts to naturally yellow and die back in late autumn.
Key Takeaway: Wait for the first light frost to blacken the leaves before digging. This ensures the rhizome has stored the maximum amount of energy for next year's growth.
Preparing for the Dig
Before you head out to the garden, gather a few basic tools. Having everything ready makes the process quick and tidy.
- A sturdy garden fork or spade: A garden fork is often better than a shovel because it is less likely to slice through the rhizomes.
- Sharp pruners or loppers: You will need these to cut back the heavy stalks.
- A garden hose: To wash away excess soil.
- Labels and a waterproof marker: If you grow different varieties, the Medium Cannas collection offers several classic mid-height choices.
- Cardboard boxes or plastic bins: For transporting and eventually storing your plants.
What to do next:
- Identify which cannas you want to save.
- Prepare your labels (e.g., "Tall Red," "Striped Leaf," "Yellow").
- Check the weather forecast for the first frost date in your area.
Step-By-Step: Lifting Your Cannas
Lifting cannas is a physical but satisfying task. Over the course of a single summer, a small rhizome can grow into a large, heavy clump, especially with Tall Cannas.
Cut Back the Foliage
Start by cutting the stalks down to about 3 or 4 inches above the soil line. Leaving a small "handle" of the stalk makes the rhizomes easier to grab and move. It also helps you see exactly where the center of the plant is so you don't accidentally hit the rhizomes with your fork. Dispose of the blackened leaves in your compost pile, provided they are healthy and free of pests.
Loosen the Soil
Place your garden fork or spade about 6 to 12 inches away from the base of the stalks. Digging too close can damage the fleshy rhizomes. Push the fork deep into the ground and gently pry upward. Work your way around the entire clump in a circle, loosening the soil as you go.
Lift the Clump
Once the soil is loose all the way around, use your fork to lift the entire mass of rhizomes out of the hole. Because canna rhizomes are heavy and full of water, a large clump can be surprisingly heavy. If the clump is too big to lift easily, you can use your spade to carefully split it into two or three smaller sections while it is still in the ground.
Cleaning and Curing
Once the rhizomes are out of the ground, they need a bit of cleaning before they go into storage.
Remove Excess Soil
Shake the clump gently to knock off large chunks of soil. You can use your hands to pull away loose dirt from between the finger-like sections of the rhizome. Some gardeners prefer to use a hose to wash the rhizomes completely clean. This makes it easier to inspect them for any signs of damage or rot. If you do wash them, just be sure to let them dry thoroughly afterward.
Inspect for Health
Take a close look at your harvest. Healthy rhizomes should feel firm, like a fresh potato. If you see any soft, mushy, or discolored spots, use a clean knife to trim those parts away. This prevents rot from spreading to the healthy parts of the plant during the winter.
The Curing Process
Curing is a simple but vital step. It involves letting the rhizomes sit in a dry, protected area for a few days before you pack them away. This allows the "skin" of the rhizome to toughen up and any cuts or nicks to callous over.
Find a spot that is out of the rain and direct sun, such as a garage, shed, or covered porch. Spread the rhizomes out in a single layer on a piece of cardboard or a mesh screen. Let them air dry for two to four days. During this time, the outer surface will become slightly duller and more papery, which helps protect the moisture inside the rhizome throughout the winter.
Key Takeaway: Curing for a few days in a dry, shady spot allows the rhizome’s skin to toughen, creating a natural barrier against rot and dehydration.
Packing for Winter Storage
The goal of storage is to keep the rhizomes in a state of "suspended animation." You want them to stay dormant, which means keeping them cool and relatively dry, but not so dry that they shrivel up completely.
Choosing a Storage Medium
Storing rhizomes in a "medium" helps regulate moisture. There are several good options:
- Peat Moss: This is a popular choice because it holds just a tiny bit of moisture but stays fluffy and airy.
- Vermiculite or Perlite: These are sterile and excellent for preventing rot.
- Wood Shavings: Pine shavings (like those used for pet bedding) are inexpensive and work well.
- Newspaper: If you prefer a simpler approach, you can wrap individual rhizomes in several layers of dry newspaper.
Packing the Bins
Place a 2-inch layer of your chosen medium in the bottom of a cardboard box or a plastic bin. If you use a plastic bin, do not put the lid on tightly. The rhizomes are living things and need a small amount of air circulation to stay healthy.
Lay the rhizomes on top of the medium so they are not touching each other. This ensures that if one rhizome happens to develop rot, it won't easily spread to its neighbors. Cover the rhizomes with more medium until they are completely buried.
Labeling
Don't forget to put your labels inside the box or write the variety name clearly on the outside. You will be very glad you did this come springtime!
The Ideal Storage Environment
Location is everything when it comes to overwintering plants. Your storage spot needs to meet two main criteria: it must stay above freezing, and it should be cool.
The ideal temperature range is between 40°F and 50°F. If the temperature stays too warm (above 60°F), the rhizomes may try to start growing prematurely in the dark. If it drops below freezing, the water inside the rhizomes will expand and destroy the plant tissue.
Good storage locations include:
- An unheated basement
- A crawlspace
- A cool closet in a mudroom
- An attached garage (provided it stays above freezing)
Avoid storing your boxes directly on a concrete floor, as concrete can draw moisture into the box or become too cold. Instead, place the boxes on a shelf or a wooden pallet.
Overwintering Cannas in Containers
If you grow your cannas in large pots on your patio, you have an even easier option. You don't necessarily need to dig the rhizomes out of the soil. For a smaller, patio-friendly choice, Short Cannas are easy to manage in containers.
Once the foliage has been hit by frost, cut the stalks down to the soil level as usual. Move the entire pot—soil and all—into a frost-free location like a basement or garage. The soil acts as a natural insulator for the rhizomes.
Stop watering the pot entirely. You want the soil to go dormant and dry out. In the spring, you can move the pot back outside, start watering again, and the cannas will begin to sprout. However, keep in mind that cannas grow very quickly. After a year or two in the same pot, they will become "root bound." At that point, it is best to tip the pot over, harvest the rhizomes, and replant them with fresh soil.
What to do next:
- Check your storage area for temperature consistency.
- Choose between digging rhizomes or storing the entire container.
- Make sure your containers are light enough to move before they get soaked by autumn rains.
Winter Monitoring and Maintenance
Many gardeners make the mistake of "setting and forgetting" their stored rhizomes. While cannas are hardy, they do benefit from a quick check-in about once a month during the winter.
Checking for Rot
During your monthly check, look for any rhizomes that feel soft, mushy, or smell bad. If you find one, remove it immediately and throw it away. Rot can spread through the storage medium, so removing the problem early protects the rest of your collection.
Checking for Dehydration
If the rhizomes look very shriveled or feel light and "corky," they may be getting too dry. In this case, use a spray bottle to lightly mist the storage medium (the peat moss or shavings) with a little bit of water. You don't want the medium to be wet—just barely damp. This provides enough humidity to keep the rhizomes plump until spring.
Preparing for Spring Replanting
As winter fades and the ground begins to warm, your cannas will start to wake up. You may even see small white or pink "eyes" (buds) beginning to sprout on the rhizomes while they are still in their boxes. If you want a dramatic summer display next season, consider Canna Tall Tropicanna.
In most regions, you can plant cannas back in the garden once the soil has warmed to about 60°F and the danger of frost has passed. If you want to get a head start on the season, you can "pot up" your rhizomes indoors about 4 to 6 weeks before the last frost date. Plant them in pots with potting soil and place them in a sunny window. By the time the weather is warm enough to move them outside, you will already have established plants ready to take off.
Dividing Your Harvest
One of the best things about saving cannas is that they multiply. When you pull your rhizomes out of storage in the spring, you will likely find that your clumps are much larger than they were when you planted them.
You can easily divide these clumps into multiple plants. Use a clean, sharp knife to cut the rhizomes into sections. Each section should have at least one (and ideally two or three) healthy-looking "eyes." Allow the cut surfaces to dry for a day before planting. This is a wonderful way to fill more of your garden for free or to share plants with friends and neighbors.
Simple Steps for Success
Saving canna bulbs over winter is a rewarding way to extend your gardening journey. We see many gardeners transition from buying new plants every year to becoming experts at building their own "stock" of favorite varieties. It turns a one-season plant into a long-term investment in your home's beauty.
Our goal is to make the process as simple and successful as possible. Remember that gardening is an experiment, and every season brings new weather and conditions. If you lose a few rhizomes to rot or drying, do not be discouraged. Even professional growers expect a small percentage of loss during winter storage. The more you practice, the more you will learn what works best in your specific climate and storage space.
By getting the timing right, curing the rhizomes properly, and keeping them in a cool, dark place, you are setting yourself up for a magnificent display next summer. The excitement of seeing those first tropical leaves poke through the soil in the spring is well worth the small effort of autumn storage.
Key Takeaway: Successful overwintering is a balance of keeping rhizomes cool enough to stay dormant, dry enough to prevent rot, and protected enough to avoid freezing.
Conclusion
Overwintering your cannas is one of the most effective ways to ensure your garden remains lush and vibrant year after year. It is a simple process that honors the natural lifecycle of the plant and allows you to enjoy larger, more impressive displays with each passing season. By taking these few steps each autumn, you transform a beautiful tropical plant into a perennial treasure for your landscape.
- Wait for the first frost to signal dormancy before digging.
- Cure the rhizomes for several days to toughen their skins.
- Store in a cool, frost-free location with a moisture-regulating medium like peat moss.
- Check your rhizomes monthly to ensure they remain firm and healthy.
We hope this guide gives you the confidence to save your cannas this year and for many years to come. For more help with your garden planning, review our Shipping Information before placing your order at Longfield Gardens.
"Saving canna rhizomes is not just about saving money; it is about the satisfaction of watching your garden evolve and grow stronger through your own care and attention."
FAQ
Do I have to wait for the frost to kill the leaves before I dig them up?
While it isn't strictly mandatory, waiting for a light frost is highly recommended. The frost sends a signal to the plant to go dormant and move its energy stores into the rhizome. If you must dig them earlier due to travel or scheduling, wait as late into the autumn as possible so the plant has maximum time to grow and store nutrients.
Can I store my cannas in an unheated garage?
Yes, as long as the temperature in the garage stays above freezing (32°F). In very cold climates, an unheated garage might get too cold in the middle of winter. If you aren't sure, place a thermometer in the garage or keep the boxes in a more insulated area, like a basement or a crawlspace, where temperatures are more stable.
What should I do if I accidentally cut a rhizome with my shovel?
Don't worry—cannas are quite resilient. If you nick or cut a rhizome while digging, simply trim the edge to make it a clean cut and allow it to cure for an extra day or two. As long as the cut callouses over in a dry environment, the rhizome should store and grow just fine in the spring.
Should I wash all the dirt off the rhizomes before storing them?
There are two schools of thought on this. Some gardeners prefer to leave a little soil on to act as a buffer, while others prefer to wash them clean to inspect for rot. Both methods work well. The most important factor is making sure the rhizomes are dry before you pack them away in their winter storage medium.