Table of Contents
- Introduction
- Identifying the Perfect Time to Dig
- Understanding Your Gardening Zone
- The Science of Energy Storage
- Essential Tools for Digging
- Step-by-Step: How to Dig Your Cannas
- Cleaning and Inspecting the Rhizomes
- The Importance of Curing
- Preparing for Winter Storage
- Monthly Maintenance Checks
- Storing Potted Cannas
- Dividing Cannas for More Plants
- When to Replant in the Spring
- Choosing Varieties for Future Success
- Common Myths About Canna Storage
- Why We Love Cannas
- Conclusion
- FAQ
Introduction
The bold leaves and tropical blooms of cannas bring a vibrant, exotic energy to any garden. Whether you are growing tall, dramatic varieties or shorter types for containers, these plants are stars of the summer landscape. At Longfield Gardens, we want to help you enjoy these stunning flowers year after year. While cannas are remarkably easy to grow, they do need a little help to survive the winter in most parts of the country.
Knowing exactly when do you dig up cannas—which are technically called rhizomes—is the secret to a successful spring garden. If you live in a region with cold winters, the timing of your autumn cleanup is essential for the plant’s health. This article will explain how to recognize the signs that it is time to dig, how to safely lift the rhizomes, and the best ways to store them until the warmth returns.
Key Takeaway: For the healthiest plants next year, wait until the first light frost kills the top growth before you begin digging up your canna rhizomes.
Identifying the Perfect Time to Dig
The most common question gardeners ask is whether they should dig up their cannas while the plants are still green and beautiful. It can be tempting to clear the garden early during a warm autumn, but patience pays off. Your canna plants use their leaves to create and store energy throughout the summer. This energy is tucked away in the underground rhizomes to power next year’s growth.
If you dig them up too early, you might cut the energy-storing process short. We recommend waiting until the first light frost of the season. When the temperature drops below freezing for a few hours at night, the lush green leaves will turn brown or black and look somewhat wilted. This is the signal that the plant has finished its work for the year and is entering dormancy.
Waiting for this frost ensures the maximum amount of nutrients has moved from the leaves down into the "bulbs." However, you must act before the ground itself freezes solid. While the foliage can handle a light nip of frost, the rhizomes themselves are sensitive to hard freezes. If the soil freezes deep enough to reach the rhizomes, they may turn to mush and will not survive the winter.
Understanding Your Gardening Zone
The USDA Plant Hardiness Zone Map is a helpful tool for understanding your local climate. Cannas are tropical and subtropical plants that are generally hardy in zones 8 through 11.
In these warmer regions, the ground rarely freezes deep enough to damage the roots. Gardeners in these zones can often leave their cannas in the soil year-round. A thick layer of mulch can provide extra protection against occasional cold snaps.
However, if you live in zone 7 or colder, the winter temperatures will likely be too low for the rhizomes to survive outdoors. In these areas, digging and storing the plants is a necessary part of the autumn routine. Because weather patterns vary every year, it is a good idea to keep an eye on your local forecast starting in late September or October.
The Science of Energy Storage
To understand why timing matters, it helps to look at how a canna grows. The rhizome is a thick, fleshy stem that grows horizontally under the soil. Unlike a true bulb, which has layers like an onion, a rhizome is a solid storage organ.
During the peak of summer, the large leaves act like solar panels. They convert sunlight into sugars through photosynthesis. These sugars are then transported down into the rhizome. This process continues right up until the plant is killed by frost or enters natural dormancy.
By allowing the foliage to stay on the plant until the first frost, you are giving the rhizome the "fullest tank" possible. A well-charged rhizome will sprout faster and grow more vigorously when you replant it in the spring. This is why we suggest letting the plant tell you when it is ready, rather than following a strict date on the calendar.
Essential Tools for Digging
Before you head out to the garden, gather a few basic tools. Having everything ready will make the process much faster and easier on your back.
- Garden Spades or Forks: A sturdy spade or a garden fork is best for lifting the large clumps.
- Pruning Shears: You will need these to cut back the heavy stalks.
- Garden Hose: A gentle stream of water helps clean off excess soil.
- Labels and Markers: It is easy to forget which variety is which once the leaves are gone.
- Storage Containers: Cardboard boxes, plastic bins with ventilation, or wooden crates work well.
Using the right tool helps prevent "wounding" the rhizomes. A sharp spade is great, but a garden fork is often preferred because it is less likely to slice through the middle of a fleshy clump.
Key Takeaway: Use a garden fork rather than a shovel to lift the rhizomes. This reduces the risk of accidentally cutting into the fleshy storage roots.
Step-by-Step: How to Dig Your Cannas
Once the first frost has blackened the leaves, it is time to get to work. Follow these simple steps for the best results:
1. Cut Back the Foliage
Start by removing the dead leaves and stalks. Use your pruning shears to cut the stems down to about 2 to 4 inches above the soil line. Leaving a small "handle" of the stem makes it easier to move the clumps around and helps you keep track of where the center of the plant is located.
2. Loosen the Soil
Cannas can grow quite large over a single season. A single rhizome planted in May can turn into a massive clump by October. Start digging about 6 to 12 inches away from the base of the stalks. This ensures you won't accidentally spear the new growth that has spread out during the summer.
3. Lift the Clumps
Push your garden fork deep into the soil and gently pry upward. Work your way around the entire plant, loosening the soil from all sides. Once the clump is loose, lift it carefully out of the hole. If the clump is too heavy to lift all at once, you can use your spade to carefully divide it into two or three smaller sections while it is still in the ground.
4. Remove Excess Dirt
Shake the clump gently to remove large chunks of soil. You can use your hands to brush away loose dirt. It is not necessary to get the rhizomes perfectly clean at this stage, but removing the bulk of the soil will make the next steps much easier.
Cleaning and Inspecting the Rhizomes
After lifting, take a moment to look at what you have harvested. This is the best time to check the health of your plants. Healthy rhizomes should feel firm and heavy for their size. They are often white, tan, or pinkish in color, depending on the variety.
If you notice any soft, mushy, or smelly spots, those areas are likely suffering from rot. You should trim away any damaged parts with a clean knife. If a whole section looks diseased, it is best to discard it rather than store it with your healthy plants.
You can also rinse the rhizomes with a garden hose to get a better look at them. However, do not use high-pressure water, as this can tear the delicate skin. The skin of the rhizome acts as a barrier against fungus and bacteria, so we want to keep it intact.
The Importance of Curing
Curing is a simple but vital step that many gardeners skip. Curing is the process of 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 "callous over" any small nicks or cuts made during the digging process.
To cure your cannas, find a dry, frost-free location with good air circulation. A garage, shed, or covered porch works perfectly. Spread the rhizomes out in a single layer on a piece of cardboard or a newspaper. Do not stack them on top of each other, as they need air to reach all sides.
Let them sit for about 3 to 7 days. The goal is for the outside to feel dry to the touch, but the rhizome itself should still be firm and fleshy inside. If the weather is very humid, they may need a full week. If it is dry and breezy, three days might be enough.
Preparing for Winter Storage
Once your cannas are cured, they are ready for their winter nap. The goal of storage is to keep them dormant, which means keeping them cool and relatively dry, but not so dry that they shrivel up completely.
Choosing a Storage Medium
Storing the rhizomes in a "medium" helps regulate moisture levels. Some popular options include:
- Peat Moss: This is excellent for holding just a tiny bit of moisture without being wet.
- Vermiculite: A sterile mineral that provides great insulation and moisture control.
- Wood Shavings: Cedar or pine shavings (like the kind used for pet bedding) allow for good airflow.
- Newspaper: Simply wrapping each clump in a few sheets of newspaper is a low-cost, effective method.
Packing the Containers
Place a layer of your chosen medium in the bottom of a box or crate. Lay the rhizomes on top, making sure they aren't crowded. Cover them with more medium and repeat the layers if necessary. If you are using plastic bins, do not put the lid on tight. Rhizomes are living things and need a small amount of oxygen. Leaving the lid slightly ajar or drilling a few holes in the sides of the bin will prevent moisture from building up and causing rot.
Finding the Right Location
The ideal storage temperature is between 40°F and 50°F. A cool basement, a crawl space, or an insulated (but not freezing) garage are usually the best spots. If the area is too warm, the cannas might try to sprout prematurely. If it is too cold, they may freeze and die.
Key Takeaway: Success in storage comes down to "cool and dry." Aim for a temperature around 45°F and check your rhizomes once a month for any signs of trouble.
Monthly Maintenance Checks
Even though the plants are dormant, it is a good idea to check on them once a month during the winter. This takes only a few minutes but can save your entire collection.
When you open your storage boxes, look for two things: rot and shriveling.
- If you see rot: If a rhizome feels mushy or looks fuzzy with mold, remove it immediately. Mold can spread quickly from one plant to another. If only a small tip is affected, you can cut it off and let the healthy part dry out before putting it back.
- If you see shriveling: If the rhizomes look wrinkled and feel very light, they are losing too much moisture. Use a spray bottle to lightly mist the storage medium with water. You don't want it to be wet—just slightly damp to the touch.
This "middle ground" of moisture is the only tricky part of storing cannas. Every home has a different humidity level, so you will quickly learn what works best in your specific storage space.
Storing Potted Cannas
If you grow your cannas in large pots or decorative containers, container-friendly cannas are an even easier option. You don't necessarily have to dig them out of the soil. When the frost hits and the leaves turn brown, cut the stalks down to the soil level as you would with garden plants.
Instead of digging them up, simply move the entire pot into a cool, dark, frost-free area like a basement or garage. Stop watering them completely. The soil in the pot will act as a natural insulation for the rhizomes. In the spring, you can bring the pot back into the light, give it a good soak of water, and wait for the new shoots to appear. This is a great time-saving trick for container gardeners.
Dividing Cannas for More Plants
One of the most rewarding parts of digging up cannas is seeing how much they have multiplied. A single rhizome can often produce five or ten new sections in one season. You can divide these clumps either in the fall before you store them or in the spring before you plant them.
To divide them, look for "eyes." These are small, pointed bumps on the surface of the rhizome where next year’s stems will grow. Use a clean, sharp knife to cut the rhizomes into pieces. Each piece should have at least one or two healthy-looking eyes.
If you divide them in the fall, make sure to let the cut edges dry and callous over for an extra day or two during the curing process. This prevents soil-borne diseases from entering the fresh cuts. Dividing your cannas is a wonderful way to expand your garden or share your favorite varieties with friends and neighbors.
When to Replant in the Spring
The cycle completes when the weather warms up again. Just as you waited for the frost to dig them up, you should wait for the danger of frost to pass before planting them back outside.
Cannas love warm soil. In most regions, this means waiting until late May or early June. If you want to get a head start, you can "wake up" your rhizomes indoors about 4 to 6 weeks before your last frost date. Plant them in small pots with some 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 several inches of lush green growth.
Choosing Varieties for Future Success
If you find that your current cannas didn't perform as well as you hoped, it might be the variety or the location. We offer a wide range of cannas at Longfield Gardens, from the stunning orange flowers of 'Wyoming' to the bright, variegated leaves of Pretoria.
When selecting new plants, consider the height and leaf color. Some cannas are grown primarily for their flowers, while others are prized for their dramatic, banana-like foliage. Matching the right plant to your sun and soil conditions is the first step toward a successful season. Most cannas need full sun (at least 6 hours a day) and plenty of water during the heat of the summer.
Common Myths About Canna Storage
There are many "internet hacks" for storing bulbs, but simple methods are usually the most reliable. You don't need fancy equipment or expensive chemicals to keep your cannas healthy.
One common myth is that you must wash the rhizomes until they are perfectly clean. In reality, a little bit of leftover soil is harmless and can actually help prevent the rhizome from drying out too fast. Another myth is that you should store them in the refrigerator. While refrigerators are cool, they are often too dry and can lead to shriveling. A basement or cool closet is almost always a better choice.
Why We Love Cannas
Cannas are one of the most rewarding plants for any gardener. They grow incredibly fast, provide a massive amount of color, and are generally resistant to most pests and diseases. By taking the time to dig them up and store them properly, you are making a simple investment in the future beauty of your yard.
The process of digging can be a peaceful way to wrap up the gardening season. It gives you a chance to see the hidden growth that happened underground all summer long. With a little bit of practice, you will find that "putting the garden to bed" is a satisfying and enjoyable ritual.
Conclusion
Digging up canna lily bulbs is a straightforward task that ensures your tropical favorites return year after year. By waiting for the first frost to signal dormancy, curing the rhizomes properly, and storing them in a cool, dry place, you can protect your garden investment with very little effort. Gardening is a journey of learning, and mastering the timing of fall cleanup is a great skill to have.
- Wait for the first light frost to blacken the foliage.
- Cut stems to 2–4 inches and lift carefully with a garden fork.
- Cure the rhizomes for several days in a dry spot.
- Store in a cool, frost-free location at 40°F–50°F.
- Check monthly for rot or shriveling.
"Taking care of your cannas in the fall is like giving your garden a head start for next year. With just a few simple steps, those tropical blooms will be ready to dazzle you all over again when the sun returns."
We invite you to explore our selection of premium cannas and other spring-planted bulbs at Longfield Gardens to find the perfect additions to your landscape.
FAQ
Can I dig up cannas before the frost if I'm expecting a busy schedule?
Yes, you can dig them up slightly early if necessary, but it is best to wait until the foliage begins to yellow. This indicates the plant is naturally winding down. If the leaves are still vibrant green, the rhizome may not have reached its full energy capacity, but it will usually still survive the winter if handled carefully.
What happens if I forget to dig them up and the ground freezes?
If only the surface of the soil freezes, your rhizomes might still be okay. However, if a hard freeze penetrates 4 to 6 inches deep, the water inside the fleshy rhizomes will expand and burst the cell walls, turning them into a mushy mess. If you suspect they have frozen, dig one up to check; if it is firm, it may still be viable.
Do I need to treat the rhizomes with fungicide before storing?
For most home gardeners, a fungicide treatment is not strictly necessary as long as the rhizomes are properly cured. If you have had significant issues with rot in the past, you can lightly dust the cut ends with sulfur powder or a general garden fungicide. The most important preventative measure, however, is maintaining the right temperature and moisture levels.
My stored cannas have started sprouting in February. What should I do?
Early sprouting usually means your storage area is a bit too warm. If the sprouts are small, you can try to move the box to a slightly cooler (but still frost-free) location to slow them down. If the sprouts are already several inches long, you may need to pot them up in soil and treat them as houseplants until it is warm enough to move them outside.