Table of Contents
- Introduction
- Understanding the Canna Life Cycle
- When to Dig Up Canna Bulbs
- Preparing to Dig
- How to Dig Up Canna Rhizomes Safely
- Cleaning and Curing Your Cannas
- Dividing Canna Rhizomes
- Winter Storage Solutions
- Storing Potted Cannas
- Checking on Your Plants
- Preparing for Spring Replanting
- Why Quality Matters
- Conclusion
- FAQ
Introduction
There is nothing quite like the tropical flair that cannas bring to a summer garden. Their bold, oversized leaves and vibrant, torch-like flowers create a lush atmosphere that makes any backyard feel like a private getaway. At Longfield Gardens, we know that these stunning plants, like our Canna Assorted Collection, are a favorite for adding height and drama to borders and containers alike. As the season winds down, many gardeners wonder how to keep that beauty alive for next year. (longfield-gardens.com)
Knowing exactly when to dig up canna bulbs—which are technically known as rhizomes—is the secret to enjoying them season after season, and our All About Cannas guide is a helpful place to start. If you live in a region with chilly winters, a little bit of autumn preparation ensures your plants stay healthy while they rest. This guide will walk you through the timing, the visual cues to look for, and the simple steps for safely harvesting and storing your cannas. (longfield-gardens.com)
Whether you are a first-time canna grower or a seasoned gardener looking to refine your routine, we are here to make the process straightforward and rewarding. By following a few basic steps, you can protect your investment and look forward to even bigger, better blooms next summer.
Understanding the Canna Life Cycle
Cannas are tropical and subtropical plants by nature, and our Tall Cannas collection shows how much height and foliage they can bring. In their native environments, they grow year-round without a break. However, in most parts of the United States, they must adapt to a four-season climate. To survive in colder regions, the plant goes dormant. (longfield-gardens.com)
During the summer, the leaves act like solar panels. They collect energy from the sun and turn it into food. This food is then stored in the thick, fleshy underground stems called rhizomes. The bigger and healthier the rhizome, the more energy the plant has to produce flowers next year.
When the weather turns cold, the plant stops growing and prepares for a rest period. If the ground freezes solid, the water inside the rhizomes will turn to ice, causing the plant tissues to burst and rot. This is why digging them up at the right time is so important for gardeners in cooler zones.
When to Dig Up Canna Bulbs
The best time to dig up your cannas is after the first light frost of the autumn season. While it might be tempting to start as soon as the air feels crisp, waiting for that first frost is actually beneficial for the plant.
The Signal from Nature
A light frost is the most reliable signal that it is time to move your cannas indoors. You will know it has happened when the lush green or bronze leaves suddenly turn black or brown and look "melted" or wilted. This frost kills the top growth of the plant but does not yet affect the rhizomes protected underground.
Waiting for this frost allows the plant to send every last bit of energy down into the rhizomes. This maximizes the stored food supply for the following spring. It also acts as nature’s way of telling the plant to go dormant, which helps it stay stable during winter storage.
Monitoring the Weather
If you live in an area where a hard freeze (where the ground begins to freeze) happens quickly after the first frost, keep a close eye on the forecast. You want to dig up the rhizomes after the leaves die back but before the soil freezes.
Frozen soil is difficult to work with and can damage the sensitive rhizomes. Aim to complete your harvest within a week or two of that first blackened leaf appearance. If a frost hasn't arrived by late November and you are expecting a deep freeze, you can go ahead and dig them up while the foliage is still green.
Hardiness Zone Considerations
Your specific location determines whether you need to dig up your cannas at all, and a standout variety like Canna Tall Tropicanna shows why warm-zone gardeners love them. We generally follow these rules based on USDA hardiness zones: (longfield-gardens.com)
- Zones 8 to 10: In these warmer regions, cannas can usually stay in the ground all year. You can simply cut the foliage back to the ground in late fall.
- Zone 7: This is the "transition zone." Many gardeners successfully leave cannas in the ground here by applying a thick 6-to-8-inch layer of mulch, such as straw or shredded leaves, for insulation. However, if a particularly cold winter is predicted, digging them up is the safest bet.
- Zones 3 to 6: In these colder northern climates, cannas will not survive the winter in the ground. You must dig them up and store them in a frost-free location to keep them alive.
Key Takeaway: The ideal window for digging up cannas is immediately after the first light frost has blackened the leaves, but before the ground freezes solid.
Preparing to Dig
Before you grab your shovel, a few simple preparations will make the job much easier. Having the right tools on hand ensures you can work quickly and avoid damaging the plants.
Tools for the Harvest
You do not need specialized equipment to harvest cannas. A standard garden spade or a sturdy garden fork is usually the best choice. A garden fork is often preferred because it is less likely to accidentally slice through a rhizome than a solid spade blade. You will also need a pair of sharp garden shears or loppers to cut back the heavy stalks.
Cutting Back the Foliage
Once the frost has turned the leaves brown, use your shears to cut the stalks down. Leave about 2 to 4 inches of the stem attached to the rhizome. These "handles" make it easier to lift the clumps and help you identify which way is up when you replant them in the spring. Removing the bulk of the foliage now also makes the digging process much cleaner and less cumbersome.
How to Dig Up Canna Rhizomes Safely
Canna rhizomes grow outward and can form large, heavy clumps by the end of the summer, especially in vigorous growers like Canna Tall Australia. A single small rhizome planted in May can easily become a cluster the size of a basketball by October. Being gentle during the lifting process is essential for preventing bruises or wounds that could lead to rot during storage. (longfield-gardens.com)
Lifting the Clump
Start by placing your shovel or fork about 6 to 12 inches away from the base of the stems. If you dig too close, you risk cutting into the fleshy roots. Push the tool deep into the soil and gently pry upward.
Work your way around the entire plant, loosening the soil on all sides. Once the soil is loose, use the stem handles to gently lift the entire mass out of the ground. 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 hole.
Initial Cleaning
Once the clump is out of the ground, shake it gently to remove large chunks of soil. You can use your hands to brush away loose dirt, but avoid being too aggressive. The "skin" of a fresh rhizome is relatively soft and can be easily scratched.
What to do next:
- Clear a workspace in a garage, shed, or covered porch.
- Gather your garden fork and pruning shears.
- Cut the stems to about 3 inches in height.
- Loosen the soil in a wide circle around the plant before lifting.
Cleaning and Curing Your Cannas
After digging, the rhizomes need a short period of "curing." This process allows the outer skin to toughen up and any remaining soil to dry out, which is vital for preventing rot during the long winter months.
To Wash or Not to Wash?
There are two schools of thought on cleaning canna rhizomes. Some gardeners prefer to use a garden hose to wash all the soil away. This makes it easier to inspect the rhizomes for pests or soft spots. Others prefer to let the soil dry and simply brush it off.
Both methods work well. If you choose to wash them, ensure you do so gently and give them plenty of time to dry afterward. If the soil in your garden is heavy clay, washing is often the easiest way to see what you are working with. If your soil is sandy, it will likely fall away on its own once dry.
The Curing Process
Place your cleaned rhizomes in a single layer in a well-ventilated, frost-free area. A garage, basement, or shed works perfectly. Avoid placing them in direct sunlight, as this can cause them to dry out too quickly or "cook."
Let the rhizomes air-dry for about 3 to 7 days. During this time, the cut ends of the stems will callus over and the outer surface will become firm. Curing is a simple step that significantly increases the chances of your plants surviving until spring.
Dividing Canna Rhizomes
Fall is an excellent time to divide your cannas, especially if the clumps have become unmanageably large. Dividing gives you more plants to fill your garden or to share with friends and neighbors.
Look for the "eyes" on the rhizomes. These are small, rounded bumps that look similar to the eyes on a potato. Each eye is a potential new stalk. When dividing, ensure each piece has at least one or two healthy eyes and a portion of the fleshy root attached.
You can usually snap the rhizomes apart by hand at the narrow points where they join. If they are too tough, use a clean, sharp knife. If you make fresh cuts, let those pieces cure for an extra day or two to ensure the "wound" is dry before they go into storage.
Winter Storage Solutions
The goal of storage is to keep the rhizomes dormant, cool, and just moist enough that they don't shrivel up, but dry enough that they don't rot.
Choosing the Right Container
You can store cannas in cardboard box, plastic bins with the lids left slightly ajar, or even paper bags. The key is to provide a little bit of airflow so moisture doesn't get trapped.
Packing Medium
To keep the rhizomes from drying out completely, it is helpful to pack them in a moisture-regulating material. Popular choices include:
- Damp peat moss
- Vermiculite
- Wood shavings (the kind used for pet bedding)
- Dry sand
- Shredded newspaper
Layer the packing medium in the bottom of your container, place a layer of rhizomes on top (not touching each other), and cover them with more medium. Repeat this until the container is full.
The Ideal Storage Environment
Place the containers in a dark, cool spot where temperatures stay consistently between 40°F and 50°F. A cool basement, a crawl space, or an insulated garage is usually ideal.
Avoid areas that drop below freezing, as this will kill the plants. Similarly, avoid placing them near a furnace or water heater, as the warmth will either dry them out too much or trick them into sprouting too early.
Storing Potted Cannas
If you grow your cannas in large pots, the process is even simpler, and a container-friendly variety like Canna Medium Banana Punch is a good fit. You do not necessarily have to dig the rhizomes out of the soil. (longfield-gardens.com)
When the first frost hits, cut the foliage back to the soil level just as you would with garden-planted cannas. Move the entire pot into a cool, dark, frost-free location like a basement or garage. Stop watering the pot completely. The soil will dry out, and the cannas will go into a deep sleep. In the spring, you can bring the pot back outside, start watering again, and the plants will emerge when the weather warms up.
Checking on Your Plants
Gardening is a journey of observation, even in the winter. It is a good idea to check on your stored cannas about once a month. This small task helps you catch potential issues before they spread.
Open your storage bins and feel a few of the rhizomes. If they feel firm and heavy, they are doing great. If you notice any that are soft, mushy, or smell bad, remove them immediately and throw them away. This prevents rot from spreading to the healthy ones.
If the rhizomes look very shriveled and feel lightweight, they may be getting too dry. Use a spray bottle to lightly mist the packing medium with a little water. You don't want the medium to be wet, just slightly damp to the touch.
Preparing for Spring Replanting
As winter fades and the ground begins to warm, it is time to think about the upcoming growing season. This is often the most exciting part for us at Longfield Gardens, as we look forward to seeing those first green shoots.
When to Bring Them Out
Wait until the danger of frost has passed and the soil temperature has reached at least 60°F. In most regions, this happens in late May or early June. Cannas love heat, so there is no rush to put them in cold, damp ground.
Starting Early Indoors
If you want to get a head start on blooms, you can "wake up" your cannas indoors about 4 to 6 weeks before the last frost date. Plant them in pots with high-quality potting soil and place them in a sunny window or under grow lights. For a step-by-step refresher, see our How to Plant a Canna Bulb. By the time the weather is warm enough to move them outside, you will already have established plants ready to take off. (longfield-gardens.com)
Storage Success Checklist:
- Cure rhizomes for a week in a dry, shaded area.
- Store in a medium like peat moss or wood shavings.
- Keep in a dark spot between 40°F and 50°F.
- Check once a month for any signs of rot or extreme dryness.
Why Quality Matters
The health of your cannas starts with the quality of the rhizomes you begin with, and strong stock like Canna Short Orange Chocolate sets the tone for success. When you start with large, firm, high-quality stock, the plants have a much higher success rate both in the garden and during winter storage. (longfield-gardens.com)
At Longfield Gardens, we work closely with experienced growers to ensure that the plants we provide are true to variety and in excellent condition when they reach your door; see our Shipping Information page for details. We maintain our own trial gardens to observe how different varieties perform, which allows us to provide practical, real-world advice to home gardeners. (longfield-gardens.com)
If you ever have questions about your plants or need help troubleshooting, our team is always ready to support you. We stand behind our quality with a 100% guarantee because we want your gardening experience to be as joyful and successful as possible. (longfield-gardens.com)
Conclusion
Digging up canna bulbs is a simple autumn ritual that rewards you with years of tropical beauty. By waiting for that first light frost to signal dormancy, you ensure your rhizomes are packed with the energy they need for a strong start next spring. Whether you choose to store them in bins of peat moss or keep them in their summer pots, the key is providing a cool, frost-free environment where they can rest.
Gardening is all about working with the rhythms of nature. Taking these few steps in the fall turns a one-season display into a lifetime of color. It is a rewarding way to connect with your garden even as the growing season comes to a close.
- Wait for the first frost to blacken the foliage before digging.
- Cut stalks back to 3 inches and lift clumps gently to avoid damage.
- Cure the rhizomes for a week and store them in a cool, dry medium.
- Check monthly for rot and keep the temperature between 40°F and 50°F.
The effort you put into protecting your cannas during the winter pays off the moment those first vibrant sprouts break through the soil in the spring. We look forward to helping you grow your most beautiful garden yet.
FAQ
Can I leave my cannas in the ground if I live in Zone 7?
Yes, in many cases you can leave them in the ground in Zone 7, but it does come with some risk. To increase their chances of survival, cut the foliage to the ground after the first frost and apply a thick layer of mulch—at least 6 inches—of straw, leaves, or wood chips. This helps insulate the soil against deep freezes. If your garden is in a particularly exposed or wet area, digging them up is a safer option to prevent rot. If you want to double-check your climate, use the Hardiness Zone Map. (longfield-gardens.com)
What happens if I dig up my cannas before the first frost?
You can certainly dig up your cannas before the first frost if you need to finish your garden chores early. The plants will still survive, but they may not have stored quite as much energy as they would have if they stayed in the ground longer. If you choose to dig early, simply cut the green foliage back and follow the same curing and storage steps. It is better to dig them a little early than to wait too long and have the rhizomes freeze in the ground.
Do I have to wash the dirt off the cannas before storing them?
Washing the dirt off is a personal preference rather than a strict requirement. Some gardeners find that washing helps them see the "eyes" more clearly for dividing and allows them to spot any hidden pests or soft spots. However, if you have a lot of plants, simply shaking off the excess soil and letting the rest dry is perfectly fine. The most important thing is that the rhizomes are dry to the touch before they go into their winter storage containers.
Why did my canna bulbs turn mushy in storage last year?
Mushy rhizomes are almost always a result of too much moisture or temperatures that were too cold. If the storage medium was too wet, or if the containers didn't have enough airflow, rot-causing fungi can take over. Another possibility is that the rhizomes were damaged during the digging process; open wounds are entry points for rot. To prevent this, be gentle when lifting them, ensure they are fully cured (dried) for a week before packing, and store them in a spot that stays cool but never freezes.