Introduction
Watching the vibrant, tropical leaves of your cannas reach for the summer sun is one of the most rewarding parts of the gardening season. These bold plants bring a touch of the tropics to any backyard with their brilliant flowers and lush foliage. At Longfield Gardens, we want to help you enjoy that beauty year after year by mastering the simple art of winter care.
Learning exactly when to dig up canna bulbs is the first step in ensuring they stay healthy and ready for the next spring. While these plants are tough and vigorous during the summer, they need a little help to survive the winter in many parts of the country. This guide is designed for home gardeners who want clear, practical advice on timing and storage.
We will cover the visual signs that tell you it is time to grab your shovel and the best way to keep your plants safe until the warm weather returns. By following a few basic steps, you can keep your favorite varieties growing for many seasons to come. Knowing the right moment to act makes the transition from fall to winter feel like a natural part of your gardening rhythm.
The Best Time to Dig Canna Bulbs
The most common question we hear from gardeners in the fall is how to know when it is time to bring cannas indoors. The answer is written right on the leaves of the plant. Canna lilies are tropical plants that love heat, and they have a very clear way of telling you when they are ready for their winter nap.
The ideal time to dig up your canna rhizomes is shortly after the first frost of the autumn. When a light frost hits your garden, the leaves of your cannas will change from bright green or bronze to a dark, wilted black or brown. This change might happen overnight. While it might look a bit sad at first, this is actually a helpful signal that the plant has finished its work for the year.
Why Wait for the First Frost?
It may be tempting to dig your cannas up while the weather is still warm and the leaves are still green. However, waiting for that first frost is beneficial for the health of the plant. During the late summer and early autumn, cannas are busy storing energy in their underground rhizomes.
This energy is what powers the dramatic growth and beautiful blooms you see the following year. The frost acts as a natural "off switch." It tells the plant to stop sending energy to the leaves and to focus entirely on the roots. By waiting for the foliage to die back, you ensure the rhizome is as strong and healthy as possible before it goes into storage.
Avoiding the Hard Freeze
While waiting for the first frost is good, you do not want to wait too long. There is a big difference between a light frost that nips the leaves and a hard freeze that turns the soil into a block of ice. You should aim to have your cannas out of the ground before the soil itself freezes solid.
If the ground freezes deep enough to reach the rhizomes, the water inside the plant tissues can expand and cause the cells to burst. This often leads to rot once the plant is brought into a warmer environment. Most gardeners find that the window of time between the first frost and the first hard ground freeze is about one to two weeks, which gives you plenty of time to complete the task.
Key Takeaway: The perfect time to dig is right after the leaves turn dark from the first frost, but before the ground freezes solid for the winter.
Understanding Your Climate and Zones
Whether or not you need to dig your cannas at all depends on where you live. The United States is divided into USDA plant hardiness zones, and these zones act as a helpful guide for plant survival. Cannas are considered "tender perennials," which means they can survive the winter outdoors only in warmer climates.
Zones 8 and Warmer
If you live in USDA zones 8 through 11, you are in luck. In these regions, the ground typically does not freeze deep enough to harm the canna rhizomes. Most gardeners in these areas can leave their cannas in the ground all year long. You can simply cut the dead foliage back to the ground in late autumn and perhaps add a thin layer of mulch for extra protection.
Zones 7 and Cooler
For those of us in zone 7 and lower, the winter temperatures are usually too cold for cannas to survive in the garden. In these areas, digging them up is a necessary part of the annual routine. If you are unsure which zone you are in, you can find your zone on the Longfield Gardens website or by checking a local gardening map.
Microclimates and Exceptions
Sometimes, plants can surprise us. You might have a "microclimate" in your yard, such as a garden bed right against a south-facing brick wall. This wall can hold heat from the sun during the day and keep the soil just warm enough to protect the plants. However, for most of us in cold-winter areas, digging is the safest way to ensure our favorite plants return.
How to Dig and Lift Canna Rhizomes
Once the frost has arrived and the leaves have darkened, it is time to get to work. You do not need any specialized tools for this job. A sharp set of garden shears and a sturdy garden fork or shovel are all you need to be successful.
Step 1: Cutting Back the Foliage
Start by cutting the stems of the cannas back. Use your shears to cut the stalks so only about 2 to 4 inches of stem remains above the soil line. This makes the plants much easier to handle and allows you to see exactly where the base of the plant is located. Do not worry about the dead leaves; you can add those to your compost pile as long as they are free of pests.
Step 2: Digging the Perimeter
The most important rule when digging cannas is to give the plant plenty of space. Canna rhizomes can grow quite large over a single summer, often spreading much further than you expect. Start your digging at least 6 to 12 inches away from the base of the stems.
Insert your shovel or garden fork deep into the soil and gently rock it back and forth. Work your way all the way around the plant in a circle. This loosens the soil and severs any small feeder roots without harming the main rhizome.
Step 3: Lifting the Clump
After you have loosened the soil around the entire perimeter, slide your shovel under the center of the mass and lift. You will likely find a large, heavy clump of rhizomes that look a bit like ginger roots. Gently shake the clump to remove the largest chunks of soil.
If the clump is too heavy to lift all at once, you can carefully use your shovel to divide it into smaller pieces while it is still in the hole. As long as each piece has a bit of stem or a visible "eye" (a small growing point), it will grow into a new plant next year.
Action Plan for Digging:
- Wait for the foliage to turn black after a frost.
- Cut stems down to 3 inches.
- Dig a wide circle around the plant to avoid slicing the roots.
- Lift the entire clump and shake off excess dirt.
Cleaning and Curing Your Rhizomes
Before you put your cannas away for the winter, they need a little bit of preparation. This process is called "curing," and it is one of the most important steps for preventing rot. Curing allows the outer skin of the rhizome to toughen up, which helps it retain moisture during the dry winter months.
To Wash or Not to Wash?
There are two schools of thought on cleaning cannas. Some gardeners prefer to wash the soil off completely with a garden hose. This makes it easier to spot any signs of damage or disease. Others prefer to simply brush off the loose dirt and leave a small amount of soil attached.
Both methods work well. If you choose to wash them, make sure you are extra careful during the drying phase. Excess water trapped in the nooks and crannies of the rhizome can lead to mold if it does not dry quickly.
The Drying Phase
Find a spot that is out of the direct sun but has good airflow, such as a garage, a shed, or a covered porch. Spread your rhizomes out in a single layer. Do not stack them on top of each other, as this prevents air from reaching the center of the clump.
Let the rhizomes sit for a few days to a week. You will notice the outer skin becoming firmer and any remaining soil turning into a dry powder. If you have any pieces that feel soft, mushy, or smell bad, discard them now. You only want to store healthy, firm rhizomes.
Choosing the Right Storage Method
The goal of winter storage is to keep the rhizomes in a state of "suspended animation." You want them to stay cool enough that they do not try to grow, but warm enough that they do not freeze. The ideal temperature is between 40°F and 50°F.
For broader guidance, see Longfield Gardens’ guide to winter storage for tender bulbs and tubers.
Storage Containers
You have several options for containers. Many gardeners use cardboard boxes, plastic crates, or even old nursery pots. If you use plastic bins, do not put a lid on them. Canna rhizomes are living things and they need to "breathe." A sealed plastic container will trap moisture and cause the plants to rot very quickly.
Filling the Gaps
To keep the rhizomes from drying out completely, it helps to pack them in a loose material. This material acts as insulation and helps maintain a very low level of moisture. Common choices include:
- Peat Moss: This is a popular choice because it holds just the right amount of moisture.
- Sawdust or Wood Shavings: Often used for animal bedding, these are inexpensive and work well.
- Vermiculite: A mineral that is great for moisture control.
- Newspaper: You can wrap individual rhizomes in sheets of dry newspaper.
Place a layer of your chosen material in the bottom of the box, add a layer of cannas, and then cover them with more material. Repeat this until the box is full.
Where to Store Them
The best location is usually a cool basement, a crawl space, or a root cellar. An unheated garage can work, but you must be careful that the temperature does not drop below freezing during a cold snap. If you notice the temperature in your storage area getting too low, you can wrap the boxes in old blankets for extra insulation.
Winter Care and Monitoring
Storing your cannas is not a "set it and forget it" task. We recommend checking on your stored rhizomes at least once a month during the winter. This only takes a few minutes and can save your entire collection from a single bad apple.
Checking for Rot
During your monthly check, look for any rhizomes that have become soft or mushy. If you find one, remove it immediately and throw it away. Rot can spread from one rhizome to another if they are touching. By removing the problem early, you protect the rest of the box.
Checking for Dehydration
Sometimes, the air in a basement can become very dry, causing the rhizomes to shrivel up and look like raisins. If they look excessively wrinkled, use a spray bottle to lightly mist the packing material (the peat moss or sawdust). You do not want it to be wet, just slightly damp. This small amount of moisture will help the rhizomes plump back up.
Key Takeaway: A quick monthly check for rot or dryness ensures your cannas stay healthy until it is time to replant.
Growing Cannas in Containers
Many gardeners choose to grow their cannas in large pots on patios or decks. This makes the winter storage process even easier. When the frost hits, you can simply move the entire pot into a protected area like a basement or garage.
You can cut the foliage back just as you would with garden-grown plants. Some people leave the rhizomes right in the dry soil inside the pot. This is a very effective way to store them because the soil provides natural insulation. In the spring, you can simply bring the pot back outside, start watering, and wait for the new growth to appear.
For more guidance, see how to grow cannas in containers.
However, if your cannas have been in the same pot for several years, they might become "root-bound." This means the rhizomes have filled up all the available space and there is very little soil left. In this case, it is better to tip the pot over, remove the rhizomes, and divide them before storing or replanting.
Dividing Cannas for More Plants
One of the most exciting things about cannas is how quickly they multiply. A single rhizome planted in the spring can easily turn into five or ten by the fall. Digging them up is the perfect time to divide them and expand your garden for free.
How to Divide
Look at the clump of rhizomes you have lifted. You will see individual sections that look like thick fingers or tubers. Look for "eyes," which are small, pointed bumps where the new stems will grow.
You can use a sharp knife or simply snap the rhizomes apart with your hands. Ensure that each piece you keep has at least one healthy eye and a good-sized section of the rhizome to provide energy. If you have more than you need, these make wonderful gifts for neighbors and friends. We love the idea of sharing the joy of gardening with others through plant divisions.
Getting a Head Start in the Spring
When the days start getting longer and the threat of a hard freeze has passed, you can begin thinking about replanting. In most parts of the country, this happens in late April or May.
Waking Them Up
If you want your cannas to bloom earlier in the summer, you can "start" them indoors about four to six weeks before the last frost date. Simply place the rhizomes in pots with some potting soil and put them in a sunny window or under a grow light. Give them a little water, and they will soon begin to send up green shoots.
By the time the weather is warm enough to plant them outside, you will already have established plants. This is a great trick for gardeners in northern states where the growing season is shorter.
Moving Outdoors
Wait until the soil has warmed up to about 60°F before moving your cannas into the garden. If you plant them in cold, wet soil too early, they may sit dormant for a long time or potentially rot. Cannas are true sun-lovers, so choose a spot that gets at least six hours of direct sunlight every day.
When you are ready to order new varieties to add to your collection, browse Tall Cannas or the Assorted Cannas collection. We time our shipments to arrive when it is the right time to plant in your specific zone.
Summary of Canna Care
Managing cannas is a rewarding cycle that follows the seasons. By paying attention to the weather and the signals from your plants, you can keep your garden looking lush and tropical every single year. The process of digging and storing is a quiet, satisfying way to wrap up the gardening season.
- Wait for the first frost to turn the leaves dark before you start digging.
- Dig a wide circle around the plants to protect the large rhizome clumps.
- Cure the rhizomes in a dry, shaded area for a few days to toughen the skin.
- Store in a cool, dark place using peat moss or newspaper to maintain moisture.
"Taking the time to lift and store your cannas is like putting your garden's future in a safe-keeping box. It ensures that the beauty you enjoyed this summer will return even stronger next year."
We stand behind the quality of every plant we provide. If you ever have questions about your cannas or any other plants from Longfield Gardens, our team is here to help you succeed. Learn more about Longfield Gardens. Gardening is a journey, and we are happy to be part of yours.
FAQ
What happens if I dig up my cannas before the frost?
If you dig them up while the leaves are still green and the weather is warm, the plants may not have stored enough energy for the following year. While they will likely still survive, they might not grow as vigorously or bloom as early as they would have if you had waited for the frost signal.
Do I have to clean all the dirt off the rhizomes before storing?
It is not strictly necessary to remove every bit of soil, but removing the large clumps of dirt is helpful. Cleaning them makes it easier to inspect for pests or rot and prevents unwanted garden soil from making a mess in your storage area. As long as the rhizomes are dry before they go into storage, a little bit of clinging soil is fine.
Can I store canna rhizomes in the refrigerator?
While a refrigerator is cool, it is often too cold and too dry for canna storage. The ideal temperature is 40°F to 50°F, whereas most refrigerators are kept below 40°F. Additionally, the lack of airflow and the presence of ethylene gas from ripening fruits can damage the rhizomes. A cool basement or crawl space is a much better choice.
Why did my stored canna bulbs turn into mush over the winter?
Mushy rhizomes are a sign of rot, which is usually caused by too much moisture or damage during the digging process. To prevent this, ensure the rhizomes are fully cured (dried) for several days before packing them away. Also, make sure your storage container is not airtight, as this traps moisture and creates a perfect environment for rot to grow.
