How to Store Canna Bulbs for Next Year

Table of Contents

1. Introduction
2. Understanding Canna Rhizomes
3. When to Dig Your Canna Bulbs
4. Tools for the Job
5. Step-by-Step: Digging Canna Rhizomes
6. Cleaning and Curing
7. Preparing for Long-Term Storage
8. Where to Keep the Storage Boxes
9. Winter Check-Ins
10. Storing Potted Cannas
11. Spring Awakening: Preparing to Replant
12. Why Your Efforts are Worthwhile
13. FAQ

Introduction

The vibrant, tropical flair of cannas is one of the most rewarding parts of a summer garden. These cannas provide lush foliage and bold flowers that keep the landscape looking energetic even during the hottest days of August. As the season winds down, many gardeners look forward to the simple process of saving these plants so they can enjoy that same beauty again next spring.

At Longfield Gardens, we want to help you make the most of your garden by ensuring your favorite plants return year after year. Storing canna rhizomes—often referred to as bulbs—is a straightforward task that any gardener can master. This guide is designed for home gardeners who want a reliable, step-by-step method to overwinter their cannas safely and effectively.

By following a few basic steps for digging, curing, and storing, you can protect your investment and even increase your canna collection over time. Proper winter storage ensures your cannas stay healthy and ready to burst into growth as soon as the warm weather returns.

Understanding Canna Rhizomes

Before we dive into the storage process, it helps to understand what you are actually working with. While most people call them "bulbs," cannas actually grow from rhizomes. A rhizome is a fleshy, horizontal underground stem that stores energy for the plant. If you have ever seen a hand of ginger at the grocery store, you already know exactly what a canna rhizome looks like.

These thick stems are the powerhouse of the plant. Throughout the summer, the large leaves of the canna capture sunlight and turn it into energy, which is then sent down into the rhizome. This stored energy is what allows the plant to grow so rapidly and bloom so impressively every year. Because cannas are tropical plants, they are not naturally equipped to survive freezing ground temperatures. In USDA hardiness zones 8 and warmer, they can often stay in the ground all year, but in zones 7 and colder, they need a little help to get through the winter.

Think of winter storage as a long, cozy nap for your plants. When you dig them up, you are simply moving them to a "bedroom" where the temperature stays just right. This prevents the water-heavy rhizomes from freezing and turning to mush, keeping the "eyes" or growth points alive and ready for the next season.

When to Dig Your Canna Bulbs

Timing is the most important factor when it's time to bring your cannas indoors. If you dig too early, the plant hasn't finished storing all the energy it needs for next year. If you wait too long and the ground freezes solid, the rhizomes can be damaged.

The best signal comes directly from nature: the first frost. Most gardeners wait until a light frost has nipped the leaves, causing them to turn brown or black. This may look like the end of the plant, but it is actually a helpful signal. When the foliage dies back, the plant naturally enters a state of dormancy, which is a resting phase.

If you live in an area where frost comes very late, you can simply wait until the leaves begin to yellow on their own in late autumn. The goal is to give the plant as much time as possible to store nutrients without risking a deep, hard freeze that penetrates the soil. For most regions in the northern United States, this window usually opens in October or early November.

Key Takeaway: Wait for the first light frost to blacken the leaves before digging. This ensures the plant has stored maximum energy and is ready for its winter rest.

Tools for the Job

You don't need a shed full of specialized equipment to store cannas. A few basic garden tools will make the process quick and easy. Having everything ready before you start will help the job go smoothly.

• A sturdy garden fork or spade: A garden fork is often preferred because it is less likely to slice through the rhizomes than a flat shovel.
• Garden shears or a sharp knife: You will need these to trim away the spent foliage.
• A garden hose: A gentle stream of water helps remove excess soil.
• Storage containers: Cardboard boxes, paper bags, or plastic bins with the lids left off all work well.
• Packing material: Peat moss, vermiculite, perlite, or even shredded newspaper.
• Labels and a marker: It is easy to forget which variety is which once the leaves are gone!

Step-by-Step: Digging Canna Rhizomes

Digging cannas is a satisfying autumn chore. Because these plants grow so vigorously, you will likely find that the single rhizome you planted in the spring has grown into a large, heavy clump. This is one of the "easy wins" of gardening—free plants for the future!

Preparing the Plant

Start by cutting the stalks down. Use your shears to trim the stems so they are only about 2 to 4 inches tall. This gives you a clear view of where the rhizomes are located and provides a "handle" for lifting the clump without getting in the way of your digging tool.

Lifting the Clump

To avoid damaging the fleshy rhizomes, start digging about 6 to 12 inches away from the base of the stems. If you dig too close, you might accidentally chop through the heart of the plant.

Insert your garden fork or spade deeply into the soil and gently pry upward. Work your way around the entire circle of the plant, loosening the soil as you go. Once the soil is loose, you can usually lift the entire clump out of the ground quite easily. If the clump is particularly large and heavy, you may need to break it into two smaller pieces while it is still in the ground to make it easier to lift.

Initial Cleaning

Once the clump is out of the soil, give it a gentle shake to remove the largest chunks of dirt. You can use your hands to brush away loose soil. Be careful not to scrape the skin of the rhizomes, as these small wounds can sometimes lead to rot during storage.

Cleaning and Curing

After the rhizomes are out of the ground, they need a bit of "spa time" before they go into storage. This phase is called curing, and it is a vital step for preventing rot.

To Wash or Not to Wash?

Some gardeners prefer to wash their canna rhizomes with a hose to remove all traces of soil. This makes it easier to inspect the rhizomes for pests or damage. If you choose to wash them, use a gentle spray. Avoid high-pressure settings that could tear the skin.

However, washing is not strictly necessary if your soil is sandy and falls away easily. If you have heavy clay soil, a quick rinse is often the best way to get the rhizomes clean enough to store. If you do wash them, it is even more important to ensure they dry completely during the curing phase.

The Curing Process

Curing simply means letting the rhizomes air-dry in a protected spot for a few days. This allows the outer skin to toughen up and any small nicks to "callus" over.

Place your cleaned rhizomes in a single layer on a piece of cardboard, a screen, or a newspaper. Choose a spot that is dry and well-ventilated but out of direct sunlight and away from the risk of frost. A garage, a shed, or a covered porch works perfectly. Let them dry for about 3 to 7 days. By the end of this time, any remaining soil should be dry and crumbly, and the rhizomes should feel firm and dry to the touch.

What to Do Next:

• Trim stalks to 2-4 inches.
• Lift clumps carefully, starting a foot away from the stem.
• Shake off loose dirt or give them a gentle rinse.
• Lay them out in a dry, ventilated spot for 3-7 days to cure.

Preparing for Long-Term Storage

Once your canna rhizomes are cured, they are ready for their winter home. The goal of storage is to keep them dormant—not too warm (which causes them to grow), not too cold (which kills them), and not too wet (which causes rot).

Choosing a Storage Medium

You don't want to store your rhizomes completely exposed to the air, as they might shrivel up and lose too much moisture. Using a packing material helps regulate the humidity around the rhizome.

• Peat Moss: This is the most popular choice. It is naturally sterile and holds just a hint of moisture without being "wet."
• Vermiculite or Perlite: These are lightweight minerals that provide excellent aeration and help prevent rot.
• Wood Shavings: Often sold as pet bedding, these are a cheap and effective option.
• Newspaper: If you don't have other materials, wrapping each rhizome individually in several layers of dry newspaper is a simple alternative.

Packing Your Cannas

Place a layer of your chosen medium in the bottom of a sturdy cardboard box or a plastic bin. If you use a plastic bin, do not put the lid on tight; air needs to circulate to prevent moisture from building up.

Arrange the rhizomes in the box so they are not tightly packed. It is better if they aren't touching each other, as this prevents a single spot of rot from spreading to the whole batch. Cover the rhizomes with more packing material until they are completely tucked in.

Don't forget to include a label! Even if you think you’ll remember which box has the "Red King Humbert" and which has the City of Portland, memories can fade by April. Drop a tag inside the box and write the variety name on the outside.

Where to Keep the Storage Boxes

The "perfect" storage spot is cool, dark, and dry. For most people, this is a basement, a crawl space, or a cool corner of a heated garage.

The ideal temperature range is between 40°F and 50°F. If the temperature stays consistently below 40°F, you risk the rhizomes getting too cold. If it stays above 55°F, the plants might think it is spring and start to sprout prematurely, which wastes the energy they need for later.

Avoid spots near heaters, furnaces, or water heaters. You also want to avoid unheated detached sheds or garages in very cold climates, as the temperature inside those structures can easily drop below freezing during a winter cold snap.

Winter Check-Ins

Storing cannas is mostly a "set it and forget it" task, but a quick check-in once a month is a great habit. This takes only a few minutes and can save your whole collection.

During your monthly check, reach into the boxes and feel a few of the rhizomes.

• If they feel soft or mushy: This is a sign of rot. Remove the affected rhizome immediately so the rot doesn't spread. If only a small tip is soft, you can sometimes cut it off with a clean knife and let the healthy part re-dry, but usually, it's best to discard the rotted piece.
• If they feel extremely shriveled and light: They might be getting too dry. Use a spray bottle to lightly mist the packing material with a little water. You don't want it to be wet—just a tiny bit of humidity is enough to plump them back up.
• If they are sprouting: They are too warm. Move the box to a cooler location.

Storing Potted Cannas

If you grow your cannas in large pots or containers, the process is even easier. You don't necessarily have to dig them out of the soil at all.

Once the frost has hit the foliage, cut the stems down to the soil level as you would with garden-planted cannas. Instead of digging the rhizomes up, simply move the entire pot into your cool, frost-free storage area. The dry soil in the pot acts as the "packing medium" for the winter.

Stop watering the pot completely once you move it indoors. The soil should stay bone-dry throughout the winter. In the spring, you can bring the pot back into the light, give it a good soak, and watch the new shoots emerge. This is an excellent "shortcut" for busy gardeners.

Spring Awakening: Preparing to Replant

When the days start to get longer and the threat of hard frost has passed, it’s time to wake up your cannas indoors about 4 to 6 weeks before the last frost date. This usually happens in late March or April, depending on your climate.

Inspecting Your Stock

Take the rhizomes out of their winter boxes and give them a final inspection. Discard anything that didn't make it through the winter. Healthy rhizomes should feel firm and heavy for their size. You might even see small, pale "eyes" or nubs beginning to swell—these are the future stems.

Dividing for More Plants

Spring is the perfect time to divide your canna rhizomes. If you started with one clump, you might now have three or four potential plants. Use a clean, sharp knife to cut the rhizomes into sections.

Each section should have at least one or two prominent "eyes." Let the cut pieces sit out for a day or two so the raw edges can dry and callus before you put them back in the ground. This simple step prevents soil-borne fungi from entering the fresh cuts.

Giving Them a Head Start

If you live in a region with a short growing season, you can "wake up" your cannas indoors about 4 to 6 weeks before the last frost date. Plant them in pots with a bit of potting soil and place them in a warm, sunny window. By the time the outdoor soil is warm enough for planting, you will have established plants ready to take off.

If you prefer to plant directly into the garden, wait until the soil is warm (at least 60°F) and the danger of frost has completely passed. Cannas love heat, so there is no rush to get them into cold, damp spring soil. They will grow much faster if you wait for a warm stretch of weather.

Why Your Efforts are Worthwhile

It might seem like a lot of steps, but once you do it once, storing cannas becomes a quick part of your autumn routine. The satisfaction of seeing those first green spears poke through the soil in the spring—knowing they are the same plants you cared for all winter—is a wonderful feeling.

At Longfield Gardens, we believe that gardening is about the cycle of the seasons. Saving your rhizomes is not just about saving money; it’s about participating in that cycle. Over a few years, a small collection of cannas can grow into a massive display that defines your summer garden.

We stand behind the quality of our plants and want your garden to thrive. Whether you are planting new varieties or overwintering your old favorites, the goal is always the same: a beautiful, vibrant space that you can be proud of. With just a little bit of care during the winter months, your cannas will continue to provide that tropical "wow factor" for many years to come.

Final Thoughts: Proper storage transforms cannas from a one-season wonder into a lifelong garden companion. By providing a cool, dry place for them to rest, you ensure a spectacular show every summer.

• Wait for the first frost to trigger dormancy.
• Cure the rhizomes for several days to toughen the skin.
• Store in a cool, dark place (40-50°F) in a breathable medium like peat moss.
• Check monthly and discard any pieces that show signs of rot.

FAQ

Can I store canna bulbs in a plastic bag?

It is generally not recommended to store canna rhizomes in sealed plastic bags. Plastic traps moisture, which often leads to mold and rot. If you must use a bag, use a mesh bag or a paper bag, or at least poke many large holes in a plastic bag to allow for plenty of airflow. A cardboard box remains the best and most breathable option for long-term success.

Do I have to wait for a frost before digging my cannas?

While you don't have to wait for a frost, it is highly recommended. The frost acts as a biological "off switch," telling the plant to move all its remaining energy into the rhizome and go to sleep. If you dig while the plant is still actively growing and green, it may not have as much stored energy, which can lead to weaker growth the following spring. For more timing guidance, see When to Plant Canna Lily Bulbs Outside for Success.

How often should I water my stored canna bulbs?

You should not water them in the traditional sense. The goal of winter storage is to keep them dry enough to prevent rot but not so dry that they shrivel into dust. Check them once a month; if the rhizomes feel very light and look wrinkled, a light misting of the packing material with a spray bottle is all they need. Never let them sit in standing water.

What should I do if my cannas start growing in the middle of winter?

If you see green shoots appearing in January or February, your storage area is likely too warm. The plant thinks spring has arrived and is using up its stored energy. Move the storage container to a cooler spot, such as a lower shelf or a different room that stays closer to 40-45°F. You can trim off the premature shoots when you replant in the spring.