Table of Contents
- Introduction
- Understanding Canna Rhizomes
- When to Begin the Process
- Gathering Your Tools
- Step 1: Cutting Back the Foliage
- Step 2: Digging Up the Rhizomes
- Step 3: Cleaning and Inspecting
- Step 4: Dividing the Clumps
- Step 5: Curing the Rhizomes
- Step 6: Choosing the Best Storage Medium
- Step 7: Packing for the Winter
- Step 8: Finding the Perfect Storage Spot
- Step 9: Storing Cannas in Containers
- Step 10: Winter Maintenance
- Preparing for Spring
- Common Questions About Canna Storage
- Why Overwintering is Worth the Effort
- Summary of Success
- FAQ
Introduction
There is something truly special about the way cannas transform a summer garden. With their tropical, oversized leaves and vibrant, torch-like flowers, they bring a sense of exotic luxury to any backyard or patio. At Longfield Gardens, we believe that the joy of growing these beauties shouldn't end when the first autumn breeze arrives. Learning how to save your plants for next year is a rewarding part of the gardening cycle that lets you enjoy your favorite varieties season after season.
This guide is designed for any gardener who wants to keep their cannas safe through the colder months. Whether you are a beginner or have been gardening for years, the process of overwintering is a simple way to protect your investment and ensure a bigger, better show next summer. We will walk you through the timing, the digging process, and the best ways to keep your plants healthy while they rest.
Properly preparing your cannas for winter storage is an easy win that guarantees your garden will be ready to glow again as soon as the warm weather returns.
Understanding Canna Rhizomes
Before we dive into the steps, it helps to know what we are working with. While most people call them "bulbs," cannas actually grow from rhizomes. A rhizome is a thick, fleshy root that grows horizontally just under the soil surface. These roots act like a storage tank for the plant, holding all the energy and nutrients the canna needs to grow tall and produce flowers.
Because cannas are tropical plants, they are not naturally equipped to handle freezing ground temperatures. In warmer climates, like the southern United States, they can stay in the ground all year. However, in cooler regions, the water inside these fleshy rhizomes can freeze, which causes the plant to break down. By digging them up and moving them to a protected spot, you are simply giving them a cozy place to take a winter nap.
When to Begin the Process
Timing is one of the most important parts of successful winter storage. You want to give your cannas as much time as possible to store energy, but you need to get them out of the ground before the soil itself freezes solid.
The best signal to look for is the first light frost of the season. When a light frost hits, the leaves of your cannas will turn black or brown and begin to wilt. This might look like the end of the plant, but it is actually a helpful "off switch" from nature. This cold snap tells the plant to stop sending energy to the leaves and start tucking it away in the rhizomes for the winter.
If you live in an area where frost is rare, you can simply wait until late autumn when the plant begins to yellow naturally. The goal is to let the foliage die back so the energy moves downward. Once the leaves have lost their color, you are ready to start.
Key Takeaway: Wait for the first light frost to blacken the leaves before you start digging. This ensures the plant has stored maximum energy in its rhizomes for next year’s growth.
Gathering Your Tools
You don't need a lot of specialized equipment to prepare your cannas for winter. A few basic garden tools will make the job quick and easy.
- Garden Fork or Spade: A garden fork is often better than a shovel because it is less likely to accidentally slice through the rhizomes.
- Pruning Shears or a Sharp Knife: You will need these to cut back the tall stalks.
- Garden Hose: A gentle stream of water helps clean the soil off the roots.
- Labels and a Marker: If you grow different colors or varieties, the Medium Cannas collection can help you keep them straight, and labeling them now is a lifesaver come spring.
- Storage Containers: Cardboard boxes, plastic bins (left slightly open), or even sturdy paper bags work well.
- Packing Material: Peat moss, wood shavings, or newspaper will help keep the rhizomes at the right moisture level.
Step 1: Cutting Back the Foliage
Once the frost has signaled the end of the season, your first task is to remove the top growth. Canna stalks can be quite thick and fibrous, especially on taller varieties. Use your pruning shears to cut the stalks down to about 3 or 4 inches above the soil line.
Leaving a small amount of the stalk attached is helpful for two reasons. First, it gives you a "handle" to hold onto while you are digging. Second, it helps you identify which side of the rhizome is the top when it comes time to replant in the spring. You can compost the leaves and stalks you cut off, provided they are healthy and free of pests.
Step 2: Digging Up the Rhizomes
This is the part where "right plant, right place" turns into "right plant, safe space." To get the rhizomes out of the ground safely, start by stepping back about a foot from the center of the plant. Canna rhizomes like to spread out, and you want to avoid hitting them with your fork or spade.
Gently push your garden fork into the soil all the way around the clump. This loosens the earth and breaks any small feeder roots. Once the soil is loose, use the fork to pry the entire clump upward. If the clump is very large, you might need to lift it in sections, but try to keep as much of the root mass intact as possible for now.
Lift the clump out of the hole and gently shake it. Most of the loose garden soil should fall away. Do not worry if some soil remains tucked into the crevices; we will handle that in the next step.
Step 3: Cleaning and Inspecting
While some gardeners prefer to store their cannas with a bit of soil attached, most people find that cleaning them makes it easier to spot potential issues. For a broader look at planting and care, see All About Cannas.
Use a garden hose with a gentle spray to wash away the remaining dirt. Avoid using a high-pressure nozzle, as you don't want to tear the "skin" of the rhizome.
Once the rhizomes are clean, take a close look at them. You are looking for firm, healthy roots that feel heavy for their size.
- Healthy rhizomes are usually white, tan, or pinkish and feel firm like a potato.
- Damaged or soft spots should be trimmed away with a clean knife.
- Small, shriveled pieces that don't have any "eyes" (growing points) can be discarded.
Getting rid of any damaged parts now prevents rot from spreading to the healthy roots while they are in storage.
Step 4: Dividing the Clumps
One of the most exciting parts of growing cannas is how much they multiply. A single rhizome planted in May can turn into a large cluster by October. Autumn is a great time to divide these clumps, though you can also wait until spring.
To divide them now, look for the natural joints in the root system. You want each piece to have at least one or two "eyes." These eyes look like small, rounded bumps or points on the surface of the rhizome—they are the spots where new leaves will grow. Use your hands to snap the pieces apart or use a clean knife for tougher sections. How to Divide Perennials can also be a helpful reference if you want a broader dividing guide.
By dividing your cannas every year or two, you ensure the plants have enough room to grow and stay vigorous. Plus, it gives you more plants to fill your garden or share with neighbors!
Step 5: Curing the Rhizomes
Before you tuck your cannas into their winter containers, a compact choice like Canna Short Orange Chocolate benefits from a good cure.
Curing is just a fancy word for letting the outside of the rhizome dry out a bit. This process allows the skin to toughen up, which acts as a natural shield against rot and mold.
Find a dry, sheltered spot that stays above freezing. A garage, a shed, or even a corner of your basement works perfectly. Spread the rhizomes out on a layer of newspaper or a screen so that air can circulate around them. Let them sit for about 7 to 10 days.
During this time, the cut ends where you trimmed the stalks will dry and callus over. Once the surface feels dry to the touch and the leftover soil has turned to dust, they are ready for their final storage.
What to do next:
- Select a well-ventilated area for curing.
- Spread rhizomes in a single layer to ensure good airflow.
- Wait until the outer skin feels dry and firm before packing.
- Label your varieties now so you don't forget which is which.
Step 6: Choosing the Best Storage Medium
The goal of winter storage is to keep the rhizomes dormant—which means they are "asleep"—without letting them dry out completely or get so wet that they rot. To achieve this balance, we use a storage medium.
At Longfield Gardens, we have found that several different materials work well:
- Peat Moss: This is a classic choice. It holds a tiny bit of moisture but stays fluffy enough to allow air to reach the roots.
- Wood Shavings: The kind used for pet bedding is excellent. It’s clean, dry, and provides good insulation.
- Vermiculite or Perlite: These are lightweight minerals that help regulate moisture.
- Newspaper: If you don't have other materials, wrapping each rhizome individually in several layers of newspaper can also work well.
Avoid using plastic bags that are zipped shut, as these trap moisture and almost always lead to rot. If you use a plastic bin, leave the lid off or drill several large holes in the sides to let the plants breathe.
Step 7: Packing for the Winter
Start by placing a 2-inch layer of your chosen storage medium in the bottom of a cardboard box or crate. Lay your cured rhizomes on top of the medium, making sure they aren't crowded. It is best if they don't touch each other; this way, if one piece happens to develop a spot of rot, it won't easily spread to its neighbors.
Cover the first layer with more peat moss or shavings, then add another layer of rhizomes if space allows. Finish with a final layer of packing material so the roots are completely tucked in.
If you are storing multiple varieties in one box, you can use small paper bags for each type. Just put the rhizomes and a bit of peat moss inside the paper bag, write the variety name on the outside, and place the bags inside your larger box.
Step 8: Finding the Perfect Storage Spot
Where you keep your box of cannas is just as important as how you pack them. They need a location that is cool, dark, and dry.
The ideal temperature range is between 40°F and 50°F. If the temperature stays in this range, the rhizomes will stay dormant. If it gets too warm (above 60°F), they might try to start growing too early. If it gets too cold (below freezing), the rhizomes will be damaged.
Good locations include:
- An unheated basement
- A cool crawl space
- An insulated garage (as long as it doesn't drop below freezing)
- A dark closet in a cool part of the house
Keep the boxes off the floor if possible, perhaps on a shelf or a wooden pallet. This helps keep them away from any dampness that might migrate through a concrete floor.
Step 9: Storing Cannas in Containers
If you grow your cannas in pots, you have a bit of a "shortcut" available with Short Cannas.
You don't necessarily have to dig the rhizomes out of the soil. Instead, you can store the entire container.
Once the foliage has been hit by frost, cut the stalks down to the soil line just like you would for in-ground plants. Move the entire pot into your cool, dark storage area. The dry soil in the pot acts as the storage medium, protecting the rhizomes from temperature swings.
In the spring, you can simply bring the pot back out into the sun, give it some water, and wait for new growth to appear. Every couple of years, however, you should still tip the pot out and divide the rhizomes to prevent them from becoming too crowded.
Step 10: Winter Maintenance
Storing your cannas isn't quite a "set it and forget it" task. It is a good idea to check on them once a month during the winter. This only takes a few minutes but can save your entire collection.
Open the box and gently feel a few of the rhizomes.
- If they feel mushy or smell bad: This is a sign of rot. Remove the affected piece immediately and throw it away. Check the surrounding rhizomes to make sure they are still dry and firm.
- If they feel very light or shriveled: They might be getting too dry. Use a spray bottle to lightly mist the storage medium with a tiny bit of water. You don't want it to be wet—just "not bone dry."
- If you see sprouts: Your storage area might be too warm or getting too much light. Try to move the box to a cooler, darker spot.
Most gardeners find that about 80% to 90% of their stored rhizomes survive the winter. Losing a few pieces is normal, so don't be discouraged if one or two don't make it!
Key Takeaway: A quick monthly check is the best way to ensure your cannas stay healthy. Adjust the moisture slightly if they look shriveled, and remove any that show signs of soft rot.
Preparing for Spring
As winter begins to fade and the days get longer, your cannas will naturally start to wake up. You might even see small white or pink "pips" (the beginning of new sprouts) emerging from the rhizomes while they are still in the box. This is an exciting sign that they are ready for a new season!
In most regions, you can start your cannas indoors in pots about 4 to 6 weeks before the last frost date. A bold choice like Canna Tall Pretoria can be started this way for an especially strong spring launch.
If you prefer to plant them directly in the garden, wait until the soil has warmed up and there is no longer any danger of frost. Cannas love warm soil and full sun, so waiting for the right conditions will result in much faster growth.
Common Questions About Canna Storage
Many gardeners wonder if they can just leave their cannas in the ground with a heavy layer of mulch. This depends entirely on your local weather, and a hardiness zone map can help you decide. In USDA Zone 7, a thick 6-to-8-inch layer of straw or wood chips might protect the roots through a mild winter. However, if a record-breaking cold snap occurs, you might lose the plants. For most people in Zone 6 or colder, digging is the only way to guarantee they return.
Another common question is whether you should wash the rhizomes or leave the dirt on. Both methods can work. Leaving the dirt on can provide a bit of extra protection against drying out, but washing them makes it much easier to inspect for pests or rot. We generally recommend washing and curing for the best results, as it keeps the storage area cleaner and makes it easier to monitor the health of the roots.
Lastly, don't worry too much about the "perfect" storage medium. While peat moss and wood shavings are great, even shredded paper or dry leaves can work in a pinch. The most important factor is the temperature and airflow of the storage location.
Why Overwintering is Worth the Effort
Taking the time to store your cannas is one of the most sustainable ways to garden. Instead of buying new plants every year, you are participating in the natural lifecycle of the plant. Over time, your collection will grow, allowing you to create massive tropical displays that would be very expensive to buy all at once from a garden center.
There is also a great sense of satisfaction in seeing those first green shoots emerge in the spring from a plant you cared for all winter. It connects you to the seasons and makes the arrival of summer even more rewarding.
Summary of Success
Preparation for winter storage is a straightforward process that pays off in beautiful blooms year after year. By following these simple steps, you can keep your cannas thriving.
- Wait for the signal: Let the first frost tell the plant it’s time to rest.
- Be gentle: Use a garden fork and leave a few inches of stalk to protect the rhizome.
- Cure before packing: Let the roots dry for a week to toughen their skin.
- Choose a cool home: Keep them between 40°F and 50°F in a dark spot.
- Check monthly: A quick look ensures they stay healthy until spring.
"Gardening is a cycle of growth and rest. By protecting your cannas during their winter nap, you are ensuring a more vibrant and beautiful garden for the season to come."
We hope this guide makes you feel confident about saving your cannas this year. At Longfield Gardens, we love helping people grow successful, beautiful landscapes. If you have questions or need more tips on caring for your favorite bulbs and perennials, contact us.
FAQ
How long can canna rhizomes stay out of the ground during winter?
Canna rhizomes can stay in storage for 4 to 6 months, depending on your local climate. As long as they are kept in a cool, dark place and the storage medium stays slightly humid but not wet, they will remain dormant until the warmth of spring triggers them to grow again.
Can I store my cannas in a plastic bin with a lid?
It is best to avoid airtight plastic bins because they trap moisture, which leads to mold and rot. If you use a plastic bin, keep the lid off or drill several holes in the sides to allow for airflow. A cardboard box or a wooden crate is often a better choice for maintaining the right environment.
Do I need to water the canna rhizomes while they are in storage?
You should not water them like a regular houseplant, but you don't want them to become bone-dry either. If the rhizomes look shriveled or feel very light when you check them monthly, use a spray bottle to lightly mist the storage medium. The goal is to keep them just barely hydrated.
Is it necessary to use a fungicide on the rhizomes before storing?
For most home gardeners, a fungicide is not necessary if the rhizomes are properly cured (dried) for a week before packing. However, if you have had a lot of trouble with rot in the past, you can lightly dust the cut ends of the rhizomes with sulfur powder to provide an extra layer of protection.