Introduction
Canna lilies are the showstoppers of the summer garden. Their bold, tropical leaves and vibrant blossoms bring a touch of the exotic to any backyard or patio. One of the best things about these plants is how easy they are to maintain and multiply. At Longfield Gardens, we enjoy helping gardeners discover how simple it is to get more from their favorite plants.
Learning how to cut canna bulbs—which are technically called rhizomes—is a vital skill for anyone who wants to keep their garden looking lush year after year. Whether you are preparing them for winter storage or dividing them to share with friends, the process is straightforward and rewarding. This guide will walk you through every step of cutting back foliage and dividing the rhizomes for the best results.
By mastering these simple techniques, you can ensure your cannas return with even more vigor each spring.
Understanding Canna Rhizomes
To cut canna bulbs correctly, it helps to understand what you are working with. While most people call them bulbs, cannas grow from rhizomes. A rhizome is a thick, fleshy underground stem that grows horizontally just beneath the soil surface.
These rhizomes act as energy storage units for the plant. They hold all the nutrients needed to send up those tall, impressive stalks and wide leaves. When you look at a canna rhizome, you will see small bumps or points. These are called "eyes," and they are the spots where new growth will emerge.
We find that understanding the structure of the rhizome makes the cutting process much more intuitive. When you cut or divide these, you are essentially creating new individual plants. As long as each piece has at least one healthy eye, it has the potential to grow into a full-sized canna lily.
When to Cut Your Cannas
The timing for cutting your cannas depends on whether you are trimming the foliage or dividing the root system. For most gardeners in the United States, this process happens in the autumn.
Cutting Back Foliage in the Fall
In most regions, cannas are tender perennials. This means they cannot stay in the ground during a freezing winter. You should wait for the first frost to touch the leaves before you begin cutting. A light frost will turn the leaves brown or black, signaling the plant to move its energy down into the rhizome for the winter.
Once the foliage has wilted from the cold, it is time to cut the stalks. This step makes it much easier to dig up the rhizomes without a massive amount of leafy weight in the way.
Dividing the Rhizomes
While you can divide the rhizomes in the fall right after digging them up, many gardeners prefer to wait until spring. Dividing in the spring allows you to see exactly where the new growth is starting. This makes it easier to identify the "eyes" and ensures you are making the most productive cuts. However, if you have a very large clump that is difficult to store, cutting them in the fall is perfectly fine.
Key Takeaway Wait for the first frost to kill off the foliage before cutting back the stalks. This ensures the plant has stored maximum energy in the rhizomes for next year’s growth.
Tools for the Job
Having the right tools makes the process of cutting canna bulbs quick and clean. You do not need professional-grade equipment, but your tools should be sharp and well-maintained.
- Hand Pruners or Loppers: These are best for cutting through the thick, watery stalks of the foliage.
- A Sharp Garden Knife or Serrated Tool: This is necessary for dividing the tough, woody rhizomes.
- A Garden Fork or Shovel: Use this to gently lift the clumps from the ground.
- Rubbing Alcohol: Use this to clean your blades between plants. This prevents the spread of any soil-borne diseases.
- Gloves: Canna stalks are juicy and can be messy. Gloves keep your hands clean and protected.
We recommend cleaning your tools before you start and after you finish. A quick wipe with rubbing alcohol or a mild bleach solution keeps your garden healthy.
Step-by-Step: Cutting Back the Foliage
The first type of "cutting" you will do involves removing the top growth. This is a simple process that prepares the plant for its dormant period.
- Wait for the Frost: As mentioned, let the frost naturally end the growing season. The leaves will go from a vibrant green or burgundy to a dull brown.
- Position Your Shears: Hold your pruners about 2 to 4 inches above the soil line. You do not want to cut flush with the ground, as leaving a small "handle" of the stalk makes the rhizomes easier to manage later.
- Make the Cut: Snip the stalks off one by one. Canna stalks are very soft and moist, so they should be easy to cut through.
- Clear the Area: Remove the old foliage and compost it, provided the plants were healthy and free of pests. Removing the debris helps prevent insects from overwintering near your garden beds.
What to do next
- Check the weather forecast for the first frost date in your area.
- Ensure your pruners are sharp and ready for the task.
- Prepare a space for the discarded foliage.
Lifting the Canna Clumps
Before you can cut the bulbs themselves, you must get them out of the ground. This should be done carefully to avoid bruising the fleshy rhizomes.
Start by digging a wide circle around the base of the plant. We suggest staying at least 6 to 12 inches away from the stalks. Canna rhizomes can spread surprisingly far in a single season. Inserting your shovel or garden fork too close to the center can slice through the rhizomes prematurely.
Gently pry upward from several angles around the clump. The goal is to lift the entire mass of roots and soil at once. Once the clump is loose, grab the stalks you left behind and lift the plant out of the hole. Shake off the excess soil so you can see what you are working with.
If the soil is particularly heavy or clingy, you can use a garden hose to gently wash the rhizomes. This makes it much easier to see the growing points and find the best places to make your cuts.
How to Cut and Divide Canna Rhizomes
Now we come to the core task: dividing the rhizomes. This is done to prevent the plants from becoming overcrowded and to create new plants for your garden.
Identifying the Eyes
Look closely at the cleaned rhizomes. You will see small, pointed nubs that look a bit like the "eyes" on a potato. These may be pink, white, or light green. Each section you cut must have at least one of these eyes to grow. For the best results, aim for two or three eyes per division. This gives the new plant a "head start" with more energy and growth points.
Making the Cut
Use a sharp, sterilized knife to cut through the bridge of tissue connecting the rhizomes. You want to make a clean, swift cut rather than a ragged one. A clean cut heals faster and is less likely to rot.
If the clump is very large and old, the center may be woody and lack eyes. You can discard these older, "spent" pieces and focus on the firm, younger rhizomes growing around the edges of the clump. These younger sections are much more vigorous.
Sizing Your Pieces
Ideally, each division should be about the size of a large potato or a clenched fist. If you cut the pieces too small, the plant will spend its first season building up its energy instead of blooming. Keeping the sections substantial ensures you will have beautiful flowers in the very first summer.
Curing the Cuts
Once you have finished cutting the rhizomes into sections, they need to "cure." This means letting the cut ends dry out and form a callous.
Lay the pieces out in a dry, shaded area for 24 to 48 hours. This protective layer acts as a barrier against moisture and fungi once the rhizomes are stored or replanted. Some gardeners like to dust the cut ends with garden sulfur to further prevent rot, but a simple air-dry is usually sufficient.
Storage After Cutting
If you are cutting your cannas in the fall, you will need to store them until the following spring. Proper storage is the key to ensuring your hard work pays off with healthy plants next year.
At Longfield Gardens, we recommend storing rhizomes in a cool, dark, and dry place. A basement, crawlspace, or unheated garage that stays above freezing is perfect.
Place the cured rhizomes in a sturdy container, such as a plastic bin or a cardboard box. Layer them with a slightly damp medium to keep them from drying out completely. Good options include:
- Peat moss
- Vermiculite
- Perlite
- Wood shavings
The medium should feel barely damp—like a wrung-out sponge. If it is too wet, the rhizomes will rot. If it is bone-dry, they will shrivel up. Check on your stored cannas once a month. If they look wrinkled, give the packing material a light mist of water. If you see any soft or mushy spots, remove those pieces immediately to keep the rest of the batch healthy.
Key Takeaway Proper storage requires a balance of moisture. Use peat moss or wood shavings and keep the temperature between 40°F and 50°F.
Replanting Your Cut Cannas
When spring arrives and the danger of frost has passed, it is time to bring your cut cannas back into the light. This is the most exciting part of the process, as you get to see your new divisions take life.
Wait until the soil has warmed to at least 60°F before planting. Cannas love heat and will sit dormant in cold, wet soil, which can lead to problems. Choose a spot with full sun—at least six to eight hours of direct light daily.
- Prepare the Soil: Dig a hole about 4 inches deep. Cannas appreciate rich soil, so mixing in some compost or well-rotted manure is a great idea.
- Placement: Lay the rhizome in the hole horizontally. Ensure the eyes are pointing upward. If you aren't sure which way is up, don't worry; the plant will figure it out, but pointing the eyes up gives it a faster start.
- Spacing: Space your divisions about 1 to 2 feet apart. Remember that these small pieces will grow into large, leafy plants by mid-summer.
- Watering: Water them in well to settle the soil around the roots. Once they start growing, cannas are thirsty plants and enjoy regular moisture.
Growing Cannas in Containers
If you don't have a lot of garden space, you can still enjoy the tropical look of cannas by planting canna rhizomes in containers. This is also a great way to "start" your cannas early indoors if you live in a cold climate with a short growing season.
When planting in containers, use a high-quality potting mix. Ensure the pot has plenty of drainage holes at the bottom. A large pot (at least 12 inches in diameter) is best, as cannas grow quickly and can become top-heavy.
Place the pot in a sunny spot and keep the soil consistently moist. Container plants dry out faster than those in the ground, so you may need to water every day during the heat of summer. You can move the entire pot into a frost-free area for the winter, cutting back the foliage just as you would for garden-grown plants.
Troubleshooting Common Issues
Even with the best care, you might run into a few questions while learning how to cut canna bulbs. Most issues are easy to solve with a few simple adjustments.
Rhizomes are Mushy
If a rhizome feels soft or squishy when you dig it up or during storage, it has likely started to rot. This usually happens if the soil was too wet or if the storage medium had too much moisture. Discard any mushy pieces. If only a small part is soft, you can try cutting it back to healthy, firm tissue, curing it again, and keeping a close eye on it.
No Eyes Visible
Sometimes, a section of rhizome looks healthy but doesn't have any obvious eyes. This is common with older sections from the center of a clump. If you don't see any growing points, it is best to discard that piece and use the vigorous outer sections instead. Without an eye, the rhizome cannot produce new stems.
Small Blooms or No Growth
If your divided cannas grow leaves but no flowers, they may not be getting enough sun or nutrients. Ensure they are in a spot with at least six hours of full sun. A balanced, slow-release fertilizer applied in early summer can also give them the boost they need to produce those spectacular blooms.
Safety and Care
While gardening is a safe and relaxing hobby, there are a few things to keep in mind when working with cannas.
- Toxicity: Canna lilies are generally considered non-toxic to humans and pets. However, it is always a good practice to keep garden plants out of reach of curious children and animals. Digging up and storing "bulbs" can sometimes attract pets who like to chew on things.
- Sap: The stalks of cannas are very watery. The sap is not typically irritating, but it can stain clothes. Wearing an old shirt and garden gloves will keep you clean.
- Tool Safety: Always cut away from your body when using a garden knife or pruners. Keep your fingers clear of the blades, especially when cutting through the tough, woody parts of a rhizome clump.
Conclusion
Cutting and dividing canna bulbs is one of the most practical ways to expand your garden for free. By following a few simple steps—waiting for the frost, using sharp tools, and ensuring every piece has a healthy eye—you can transform a single plant into a stunning tropical border. At Longfield Gardens, we believe that these small tasks make gardening a truly rewarding experience.
The beauty of cannas is their resilience. They are forgiving plants that respond well to a little bit of attention in the autumn and spring. As you get comfortable with the process, you will find that managing your canna collection becomes a favorite part of your gardening routine.
- Wait for frost to cut back foliage to 2–4 inches.
- Dig carefully to lift the entire rhizome clump.
- Divide rhizomes into pieces with 2–3 eyes each.
- Cure the cuts for 24–48 hours before storing or planting.
"Gardening is a journey of growth, and dividing your cannas is a wonderful way to see your progress year after year."
Ready to add more color to your yard? Explore our tall cannas and start planning your next garden masterpiece today.
FAQ
Can I cut canna lilies back in the summer?
You can remove spent flower stalks during the summer to keep the plant looking tidy, but you should not cut the foliage back to the ground until the end of the season. The leaves are needed to gather sunlight and create energy for next year's blooms. Deadheading the old flowers will often encourage the plant to produce more blossoms throughout the season.
Do I have to divide my cannas every year?
You do not have to divide them every year, but we recommend doing it every 2 to 3 years. Over time, the clumps become very large and crowded, which can lead to smaller flowers and less vigorous growth. Dividing them keeps the plants healthy and gives them plenty of room to spread their roots. For additional guidance, see this guide to dividing and storing canna bulbs.
What happens if I don't cut the foliage after a frost?
If you leave the dead foliage on the plant, it won't necessarily harm the rhizomes immediately, but it can become a hiding place for pests and diseases. The decaying matter can also hold too much moisture against the crown of the plant, potentially leading to rot. Cutting it back is a much cleaner and safer approach for the health of your garden.
Can I just break the rhizomes apart with my hands?
While some rhizomes might snap apart easily, we always recommend using a sharp, clean knife. Breaking them by hand can create jagged, uneven edges that take longer to heal and are more susceptible to disease. A clean cut ensures the quickest recovery for the plant so it can focus on growing once it is replanted.
