Table of Contents
- Introduction
- Understanding Canna Rhizomes and Winter Needs
- Timing the Harvest
- Step-by-Step Digging Instructions
- Cleaning and Preparing for Storage
- The Importance of Curing
- Packing Your Cannas for the Winter
- Choosing the Perfect Storage Location
- Mid-Winter Checkups
- Dividing Your Cannas
- Bringing Cannas Out of Dormancy
- Common Myths About Storing Cannas
- Creating a More Beautiful Garden
- Summary of the Storage Process
- Conclusion
- FAQ
Introduction
Cannas are the undisputed stars of the summer garden, bringing a lush, tropical energy to any landscape with their oversized leaves and brilliant blooms. These vigorous plants are a joy to grow, and the best part is that you do not have to buy new ones every year. With just a little bit of effort in the fall, you can preserve your favorite varieties and even increase your collection for the following season.
At Longfield Gardens, we want to help you enjoy the beauty of these sun-loving plants year after year. Storing canna bulbs—technically known as rhizomes—is a straightforward process that any gardener can master. This guide is designed for home gardeners who want to keep their cannas safe during the winter months, whether you are a beginner or looking to refine your technique.
We will walk you through the entire lifecycle of winter storage, from the moment the first frost hits your garden to the day you bring your plants back out in the spring. By following a few simple steps for digging, cleaning, and storing, you can ensure your cannas remain healthy and ready to grow.
Understanding Canna Rhizomes and Winter Needs
Before we dive into the "how-to," it is helpful to understand canna rhizomes. A rhizome is a fleshy, horizontal underground stem that stores energy for the plant. Because cannas are tropical and subtropical by nature, these rhizomes are full of moisture and sensitive to freezing temperatures.
In warmer parts of the country, specifically USDA plant hardiness zones 8 through 10, cannas can often stay in the ground year-round. In these regions, the soil rarely freezes deep enough to damage the rhizomes. However, for gardeners in zones 3 through 7, the winter cold will eventually reach the rhizomes and cause them to rot if they are left unprotected.
Storing them indoors is the most reliable way to keep them alive in cooler climates. This process, often called overwintering, puts the plant into a state of dormancy. Think of it as a long winter nap where the plant rests and waits for the warmth of spring to return. Because cannas are so prolific, you will often find that the single rhizome you planted in the spring has multiplied into a large clump by autumn, giving you even more flowers for free.
Timing the Harvest
One of the most common questions we hear is exactly when to start the digging process. The goal is to give the plant as much time as possible to store energy in its rhizome before the winter sets in. As long as the leaves are green and the weather is warm, the plant is still photosynthesizing and "charging its battery" for next year.
The ideal signal to start digging is the first light frost of autumn. You will know it has happened when the lush green foliage of your cannas suddenly turns black, brown, or wilted. While this might look disappointing, it is actually a helpful natural signal. The frost tells the plant to stop growing and move all its remaining resources down into the rhizome.
If you live in an area where a hard freeze (where the ground itself freezes) happens quickly after the first light frost, you should act fast. You want to dig the rhizomes while the soil is still workable and before the cold penetrates the earth. If you miss the first frost, do not worry; as long as you dig them up before the ground freezes solid, your rhizomes should be just fine.
Key Takeaway: The First Frost Rule Wait for the first light frost to blacken the leaves before digging. This ensures the plant has stored the maximum amount of energy for its winter dormancy.
What to Do Next:
- Monitor your local weather forecast for the first frost warning.
- Gather your tools (spade, garden fork, and labels) so you are ready when the time comes.
- Identify which varieties are which if you have different colors or varieties, as they will all look the same once the leaves are gone.
Step-by-Step Digging Instructions
Once the frost has signaled it is time, the physical work begins. Digging cannas is a satisfying garden task, but it requires a bit of care to ensure you do not damage the fleshy rhizomes. A damaged rhizome is more susceptible to rot during storage, so a gentle hand is best.
Start by cutting the foliage back. Use a pair of sharp garden shears or a lopper to cut the stems down to about three or four inches above the soil line. Removing the bulky leaves makes it much easier to see where the base of the plant is and gives you a "handle" to grab later.
Next, take a garden fork or a spade and start digging about a foot away from the base of the stalks. Cannas grow outward, and the clumps can be surprisingly wide. By starting your cut a safe distance away, you reduce the risk of slicing through the rhizomes. Circle the plant with your tool, loosening the soil as you go.
Once the soil is loose, gently pry the entire clump upward. If the clump is very large, you might need to lift it in sections, but try to keep it as intact as possible at this stage. Lift the clump out of the hole and shake off the loose clods of dirt. You will likely see a complex network of interconnected, potato-like structures—these are your future flowers.
Cleaning and Preparing for Storage
After the rhizomes are out of the ground, they need a little bit of grooming before they go into their winter containers. There are two schools of thought on cleaning: shaking and rinsing.
Most gardeners find that simply shaking off the excess soil is sufficient. You don't need the rhizomes to be perfectly clean; a little bit of clinging soil can actually help keep them from drying out too fast. However, if your soil is heavy clay or very wet, you might want to give them a gentle rinse with a garden hose.
If you do choose to rinse your canna rhizomes, it is vital that you allow them to dry completely before packing them away. Moisture is the biggest enemy of a dormant rhizome, and packing wet plants into a box is an invitation for mold and rot.
While you are cleaning, take a moment to inspect the rhizomes. Look for any soft spots, signs of insect damage, or areas that look diseased. Use a clean, sharp knife to trim away any damaged portions. It is also a good time to trim off the long, stringy roots hanging from the bottom of the rhizome, as these will simply die back during dormancy anyway.
The Importance of Curing
"Curing" is a fancy word for letting the rhizomes air dry in a protected spot for a few days. This step is essential because it allows the "skin" of the rhizome to toughen up and any cut surfaces to callous over. A well-calloused rhizome acts as its own barrier against infection.
To cure your cannas, find a dry, well-ventilated area that is out of direct sunlight and safe from freezing temperatures. A garage, a covered porch, or a shed works well. Spread the rhizomes out in a single layer on a piece of cardboard or a tray.
Let them sit for two to four days. During this time, the remaining soil will dry and fall off, and the cut stems will begin to dry out. You don't want to leave them out so long that the fleshy parts begin to shrivel or look like raisins, but they should feel dry to the touch on the outside.
Key Takeaway: The Curing Phase Air-dry your rhizomes for several days in a frost-free, shady spot. This allows wounds to heal and prevents rot during the long winter months.
What to Do Next:
- Shake off loose soil and trim away damaged sections.
- Lay the rhizomes on cardboard in a single layer.
- Wait 2–4 days until the outer surface feels dry and firm.
Packing Your Cannas for the Winter
Now that your rhizomes are clean and cured, it is time to pack them into their winter homes. The goal of storage is to maintain a very delicate balance: you want the environment to be dry enough to prevent rot, but humid enough that the rhizomes do not completely dehydrate.
There are several different materials you can use to pack your cannas. These materials act as insulation and help regulate moisture. Popular choices include:
- Peat Moss: This is a favorite because it holds a tiny bit of moisture while remaining airy.
- Vermiculite or Perlite: These mineral-based options are excellent for moisture control.
- Wood Shavings: Often sold as pet bedding, these are inexpensive and provide great airflow.
- Newspaper: Shredded or wrapped layers of newspaper are a classic, low-cost method.
Choose a container that allows for some air exchange. Cardboard boxes, wooden crates, or plastic bins with the lids left slightly ajar are all good options. Avoid airtight plastic bags or sealed containers, as these trap moisture and lead to rot.
Start by placing a two-inch layer of your chosen packing material in the bottom of the container. Lay the rhizomes on top, making sure they aren't all mashed together. If you have a lot of them, you can create multiple layers, separating each layer with more packing material. If you are storing different colors or varieties, we recommend labeling them now with a permanent marker or a tag, as you will not be able to tell them apart by looking at the bare rhizomes in the spring.
Choosing the Perfect Storage Location
Where you put the box is just as important as how you pack it. Canna rhizomes need to stay cool to remain dormant, but they must never freeze. The ideal temperature range for storage is between 45°F and 55°F.
If the storage area is too warm (above 60°F), the rhizomes may think it is spring and start to grow prematurely in the dark. This wastes the energy they have stored and results in weak, pale sprouts. If the area is too cold (below 40°F), you run the risk of the rhizomes being damaged by a sudden cold snap.
Common successful storage locations include:
- Unheated Basements: Usually the most consistent environment.
- Crawl Spaces: These often stay at a perfect, cool temperature.
- Root Cellars: The traditional choice for keeping bulbs and tubers.
- Attached Garages: Be careful here; ensure the spot you choose doesn't drop below freezing during the coldest nights of January.
Keep the boxes off the floor if the ground is made of concrete, as concrete can pull cold and moisture into the box. Placing them on a shelf or a wooden pallet is a simple way to keep them at a more stable temperature.
Mid-Winter Checkups
Storing cannas is not a "set it and forget it" task. We recommend checking on your stored rhizomes once a month throughout the winter. This takes only a few minutes but can save your entire collection if something starts to go wrong. For more storage guidance, see our guide on how long canna lily bulbs last.
When you open the box, look for two things: rot and shriveling. If you find a rhizome that has turned soft, mushy, or smells bad, remove it immediately. Rot can spread from one rhizome to another, so catching it early is vital.
On the flip side, if the rhizomes look very shriveled or feel light and hollow, they may be getting too dry. In this case, use a spray bottle to lightly mist the packing material with water. You don't want it to be wet—just a tiny bit of moisture is enough to stop the dehydration process. Usually, the natural moisture within the rhizome is enough to get it through the winter, but in very dry climates or heated basements, a quick misting can be a lifesaver.
Key Takeaway: The Monthly Inspection Check your rhizomes once a month. Remove any mushy ones to prevent the spread of rot, and lightly mist the packing material if the others look excessively shriveled.
What to Do Next:
- Set a monthly reminder on your phone or calendar.
- Keep a spray bottle nearby for quick moisture adjustments.
- Discard any rhizomes that show signs of decay immediately.
Dividing Your Cannas
One of the most rewarding aspects of growing cannas is how much they multiply. A single rhizome can turn into a massive clump in just one season. You can divide these clumps either in the fall before you pack them away or in the spring before you plant them.
Many gardeners prefer to wait until spring to divide because the "eyes" (the small bumps where the new growth will emerge) are easier to see once the plant begins to wake up. However, if your clumps are simply too large to fit into your storage boxes, you can divide them in the fall.
To divide, use a clean knife or simply snap the rhizomes apart by hand. Each new piece should have at least one or two "eyes" to ensure it has the potential to grow a healthy new plant. Large, healthy sections about the size of a potato are ideal. If you divide in the fall, remember to let the freshly cut ends dry and callous for an extra day before packing them into the storage medium.
Bringing Cannas Out of Dormancy
As the days get longer and the threat of frost passes, it is time to wake up your cannas. This usually happens in late March or April, depending on your local climate. At our trial gardens, we find that giving cannas a "head start" indoors can result in flowers much earlier in the summer.
About four to six weeks before your last expected frost date, you can take the rhizomes out of their winter boxes. Inspect them one last time, discarding any that didn't make it through the winter. You can plant them in large pots with quality potting soil and place them in a warm, sunny window.
If you prefer to plant directly into the garden, wait until the soil has warmed up to at least 60°F and there is no longer any danger of frost. Cannas love warm soil and will sit sulking if they are planted in cold, wet earth too early. When you do plant them, place them about 4 inches deep with the eyes pointing upward.
Common Myths About Storing Cannas
There is a lot of advice online about storing tropical plants, and not all of it is helpful. One common myth is that you must wash every bit of soil off the rhizomes. In reality, as mentioned earlier, a little bit of dirt is harmless and can actually be beneficial.
Another myth is that cannas can be stored in the refrigerator. While refrigerators are cool, they are often too cold and too dry for long-term rhizome storage. Additionally, fruits like apples give off ethylene gas as they ripen, which can actually damage or kill the dormant "eyes" on your canna rhizomes. Stick to a basement or crawl space for the best results.
Lastly, some people believe that you should never cut the stems until you are ready to plant in the spring. While you can leave them long, it makes storage much more difficult and provides more surface area for moisture to escape. Cutting them down to a few inches is a standard, professional practice that works well for home gardeners.
Creating a More Beautiful Garden
The process of storing canna bulbs is a rhythmic part of the gardening year. It marks the transition from the vibrant energy of summer to the quiet rest of winter. By taking these few simple steps, you are participating in a tradition that gardeners have used for centuries to preserve and propagate beautiful plants.
Every rhizome you save is a piece of your garden's history. Over time, as you divide and replant your collection, you may find you have enough to share with friends, family, and neighbors. This is how many of the most beloved garden varieties have been passed down through generations.
At Longfield Gardens, we take pride in providing quality plants that are true to variety and ready to perform. Whether you are starting with new rhizomes from us or storing your own from last year, the goal remains the same: a spectacular, worry-free display of color and texture in your yard.
Key Takeaway: Success Through Simplicity Most canna storage failures are due to extreme cold or excess moisture. Keep them cool, keep them mostly dry, and check them occasionally to ensure a successful spring return.
Summary of the Storage Process
To recap the most important points for successful canna storage, follow this simple workflow:
- Wait for the frost: Let a light frost blacken the leaves before you begin.
- Cut and dig: Remove the foliage and carefully lift the clumps with a garden fork.
- Clean and cure: Shake off the dirt and let the rhizomes air dry for a few days in a shady, frost-free spot.
- Pack loosely: Use a breathable medium like peat moss or wood shavings in a cardboard box.
- Store cool: Find a spot between 45°F and 55°F that will not freeze.
- Check monthly: Remove any rotting pieces and mist with water if the rhizomes appear extremely shriveled.
Following these steps ensures that the investment you made in your garden continues to pay off year after year. Gardening is a journey of learning and observation, and mastering the art of overwintering is a major milestone for any home gardener.
Conclusion
Storing canna bulbs is one of the most rewarding ways to extend the life of your garden and enjoy the lush, tropical beauty of these plants without a recurring cost. While it requires a bit of effort in the autumn, the payoff of seeing those first green shoots emerge in the spring makes it all worthwhile. By focusing on the basics—proper timing, careful digging, and a stable storage environment—you can be confident that your cannas will return bigger and better each year.
We encourage you to experiment with different varieties and storage methods to see what works best in your specific microclimate. Remember that gardening is meant to be an enjoyable and rewarding activity, and even "mistakes" are simply opportunities to learn more about the plants we love.
As you plan for next season, we invite you to explore the wide range of spring-planted bulbs and perennials available at Longfield Gardens. Our team is always here to support you with quality plants and practical advice to help you create the garden of your dreams.
- Wait for frost to signal dormancy before digging.
- Allow rhizomes to cure for several days to prevent rot.
- Choose a cool, frost-free storage location like a basement.
- Check your stored plants monthly to catch any issues early.
"A little bit of preparation in the fall leads to a spectacular tropical display in the summer. Storing cannas is a simple, effective way to grow your garden collection over time."
FAQ
Can I leave my cannas in the ground if I live in Zone 7?
It depends on your specific microclimate and how cold the winter gets. In Zone 7, cannas can sometimes survive if they are planted in a protected spot, such as near a south-facing wall, and covered with 6 to 8 inches of mulch like straw or leaves. However, because a particularly cold winter can still kill the rhizomes, many gardeners in Zone 7 choose to dig up at least a few "insurance" plants to store indoors just in case.
What should I do if my canna rhizomes look moldy during storage?
If you see a light dusting of surface mold, it usually means the storage environment is a bit too damp or has poor airflow. You can wipe off the mold with a dry cloth and move the box to a spot with better ventilation. However, if the rhizome feels soft or mushy under the mold, it has begun to rot and should be thrown away immediately to prevent the rot from spreading to the healthy rhizomes in the box. If you need help with an order or a product issue, contact us.
Do I need to divide the clumps before I store them?
You do not have to divide them in the fall unless the clumps are too large to handle or fit into your storage containers. Many gardeners find it easier to store the whole clump and then divide it in the spring. In the spring, the "eyes" or growth points will be more visible as the plant begins to wake up, making it easier to see exactly where to make your cuts for the best results.
My cannas are growing in pots; can I store the whole pot?
Yes, this is an excellent and easy way to overwinter cannas. After the frost kills the foliage, cut the stems back to the soil line and move the whole pot into a cool, frost-free area like a basement or garage. Stop watering the pot entirely so the soil dries out and the plant stays dormant. In the spring, you can bring the pot back into the light, resume watering, and the cannas will begin to grow again.