Table of Contents
- Introduction
- Getting the Best Start with Canna Rhizomes
- Planting Your Canna Bulbs for Success
- Summer Care: Keeping Cannas Lush and Vibrant
- Advanced Care: Deadheading and Pruning
- Caring for Cannas in Containers
- End-of-Season Care: Overwintering and Storage
- Caring for Your Bulbs During Winter Dormancy
- Troubleshooting Common Care Questions
- Conclusion
- FAQ
Introduction
There is nothing quite like the bold, tropical energy that cannas bring to a summer garden. With their oversized, banana-like leaves and brilliant blooms in shades of red, orange, and yellow, they transform any backyard into a lush retreat. Whether you are planting them in a formal flower bed or a large decorative patio pot, these plants are remarkably resilient and rewarding. At Longfield Gardens, we want to help you enjoy these showstoppers by making their care as straightforward as possible.
This guide is designed for gardeners who want to understand the simple steps required to keep cannas thriving from the first sprout of spring to the final frost of autumn. We will cover planting requirements, summer maintenance, and the essential steps for winter storage. By following a few basic principles, you can ensure your canna rhizomes—the thick, bulb-like stems—stay healthy and productive for years to come.
Getting the Best Start with Canna Rhizomes
Before you even put a shovel in the ground, caring for your cannas begins with the rhizomes themselves. While often called "bulbs," cannas grow from rhizomes, which are fleshy underground stems that store energy for the plant. The quality of the rhizome you start with directly impacts the vigor of the plant during the growing season.
When you receive your shipment, look for rhizomes that feel firm and plump. A healthy rhizome should have several "eyes" or growth points. These are the small, rounded bumps where the new stems will emerge. Typically, a rhizome with three to five eyes will produce a much fuller, more spectacular plant than a smaller one.
If you are not ready to plant immediately, store your rhizomes in a cool, dry place. Keep them in the packaging they arrived in, or place them in a breathable paper bag with some peat moss. This prevents them from drying out or sprouting too early. Ideally, you want to keep them at a temperature between 45°F and 55°F until the outdoor conditions are just right.
What to do next:
- Inspect each rhizome for firmness and visible eyes.
- Keep rhizomes in a cool, dark, dry area if planting is delayed.
- Ensure they stay dry to prevent premature rotting before they hit the soil.
Planting Your Canna Bulbs for Success
Caring for cannas is much easier when they are planted in a location that meets their basic needs. These plants are native to tropical and subtropical regions, which means they crave two things: heat and moisture.
Choosing the Right Spot
Cannas need at least six to eight hours of direct sunlight every day to produce their best foliage and flowers. While they can grow in partial shade, they often become "leggy" and produce fewer blooms. Choose a spot that is also somewhat sheltered from strong winds. Because cannas can grow tall—some varieties reach up to six or eight feet—their large leaves can act like sails and may tear or snap in a heavy storm.
Soil and Drainage
While cannas love water, they do best in soil that is rich in organic matter. Before planting, loosen the soil to a depth of about 12 inches and mix in several inches of compost or well-rotted manure. This improves the soil structure and provides the nutrients these "heavy feeders" need. If you have very heavy clay soil, adding compost will help it drain just enough so the rhizomes don't sit in stagnant water, which can cause rot.
Timing and Depth
Wait to plant until the danger of frost has passed and the soil temperature has warmed to at least 60°F. If you plant too early in cold, wet soil, the rhizomes may sit dormant for too long and begin to decay. A good rule of thumb is to plant cannas around the same time you would put tomato plants in the garden.
Dig a hole or trench about 2 to 3 inches deep. Lay the rhizome in the hole horizontally with the eyes facing upward. If you aren't sure which way is up, don't worry; the plant will naturally find its way to the surface. Space the rhizomes 18 to 24 inches apart to give them plenty of room to expand throughout the summer.
Summer Care: Keeping Cannas Lush and Vibrant
Once your cannas have sprouted and the leaves begin to unfurl, their care shifts toward maintaining steady growth. Because they grow so rapidly in a single season, they require more attention to watering and fertilizing than many other perennials.
Watering Rhythms
Cannas are one of the few garden plants that thrive in consistently moist soil. In fact, some varieties can even be grown at the edge of a pond in boggy conditions. During the heat of the summer, check the soil frequently. If the top inch of soil feels dry, it is time to water.
For plants in the ground, a deep soaking once or twice a week is usually better than a light sprinkling every day. This encourages the roots to grow deeper into the soil. If you are experiencing a drought or a week of temperatures over 90°F, you may need to water every other day. Using a layer of organic mulch, such as shredded bark or straw, around the base of the plants will help hold moisture in the soil and keep the roots cool.
Fertilizing for Foliage and Flowers
To maintain that famous tropical look, cannas need plenty of fuel. They are known as heavy feeders. We recommend applying a balanced, slow-release fertilizer shortly after the first leaves emerge. You can follow this up with a second application in mid-summer.
If you prefer liquid fertilizers, a fish emulsion or a product formulated for roses or tomatoes works well. High-nitrogen fertilizers will encourage taller stems and bigger leaves, while a formula with slightly more phosphorus will help boost flower production. Always follow the instructions on the fertilizer label to avoid over-feeding, which can sometimes burn the roots.
Summer Care Action List:
- Monitor soil moisture daily during heatwaves.
- Apply a 2-inch layer of mulch to conserve water.
- Feed plants every 4-6 weeks with a balanced fertilizer.
- Watch for the first signs of growth, which may take 3-4 weeks to appear.
Advanced Care: Deadheading and Pruning
One of the best ways to care for your cannas is to stay on top of pruning. While cannas don't require complicated "training," a little bit of maintenance keeps them looking tidy and encourages a longer blooming season.
The Art of Deadheading
Deadheading is the process of removing faded flowers before they go to seed. When a canna bloom withers, the plant begins to put energy into producing seed pods rather than new flowers. By snipping off the spent blooms, you signal to the plant that it should keep producing more flower spikes.
To deadhead correctly, look at the stem just below the faded flower. You will often see a new bud waiting to bloom just a few inches down. Carefully snip off the old flower without damaging the new bud. Once an entire flower stalk has finished blooming and no more buds are visible, you can cut that specific stalk back to the foliage line.
Leaf and Stem Maintenance
As the season progresses, some of the lower leaves may turn brown or look "trashy" due to wind or sun exposure. This is perfectly normal. You can simply trim away these individual leaves at the base of the stem to keep the plant looking fresh.
If you notice large, round seed pods forming, you can choose to leave them for visual interest or clip them off. While you can grow cannas from these seeds, it is a slow process, and the resulting plants may not look exactly like the parent. For most gardeners, focusing on the health of the rhizome is a more effective way to propagate the plants.
Caring for Cannas in Containers
Short cannas growing in pots is a fantastic way to bring height to a patio or balcony. However, container-grown cannas require slightly different care than those planted in the landscape.
Choosing the Right Pot
Because cannas grow large and have an extensive root system, they need a big "home." A pot that is at least 15 to 18 inches in diameter is necessary for a single rhizome. Ensure the container has plenty of drainage holes. While cannas like moisture, they do not want to sit in a pot that has no way to shed excess water, as the soil can become sour and the roots can rot.
Potting Mix and Placement
Use a high-quality, well-draining potting soil rather than garden soil, which is too heavy for containers. Since pots dry out much faster than the ground, you may need to water container cannas every single day during the summer. If the pot is small or the weather is particularly windy, check it twice a day.
Feeding Container Plants
Nutrients leach out of container soil every time you water. Therefore, container cannas need more frequent feeding than those in the garden. A water-soluble fertilizer applied every two weeks is a great way to ensure they have the energy to keep blooming.
Key Takeaway: Container cannas are beautiful but "thirstier" and "hungrier" than those in the ground. Consistent watering and bi-weekly feeding are the keys to success in pots.
End-of-Season Care: Overwintering and Storage
In USDA hardiness zones 7 through 10, cannas can often stay in the ground year-round with a thick layer of mulch for protection. However, in colder climates (Zone 6 and below), the rhizomes must be "lifted" and stored indoors to survive the winter. Caring for your bulbs during this dormant period is just as important as caring for them during the summer.
When to Lift the Rhizomes
Wait until the first frost of autumn has blackened the foliage. This frost serves as a signal to the plant to move its energy down into the rhizome for winter. Once the leaves are brown and limp, cut the stems down to about 4 to 6 inches above the soil line.
Digging and Cleaning
Using a garden fork or a shovel, carefully dig around the clump of cannas. Be sure to start at least a foot away from the stems to avoid slicing into the rhizomes. Gently lift the entire clump out of the ground.
Shake off the excess soil. You don't need to scrub them perfectly clean, but removing the bulk of the dirt makes storage easier. You can use your hands to gently pull apart large clumps into smaller, more manageable sections. Ensure each section has at least one or two healthy eyes.
The Curing Process
Before putting them away for the winter, "cure" the rhizomes by letting them sit in a dry, frost-free area like a garage or shed for two to three days. This allows the outer skin to toughen up slightly, which helps prevent rot and moisture loss during storage.
Caring for Your Bulbs During Winter Dormancy
Proper winter storage is the final step in the annual care cycle. The goal is to keep the rhizomes dormant—neither too wet (which causes rot) nor too dry (which causes them to shrivel and die).
Choosing a Storage Medium
At Longfield Gardens, we recommend storing canna rhizomes in a breathable container like a cardboard box, a plastic bin with holes, or a paper bag. To maintain a tiny bit of moisture, pack them in a slightly damp medium such as:
- Peat moss
- Perlite or vermiculite
- Wood shavings or sawdust
- Shredded newspaper
Temperature and Location
Store the containers in a cool, dark place where the temperature stays consistently between 40°F and 50°F. An unheated basement, a crawl space, or a cool closet are usually ideal. Avoid areas that might freeze, like an uninsulated outdoor shed, as a hard freeze will kill the rhizomes.
Monthly Check-ins
Set a reminder to check on your stored bulbs once a month. If the rhizomes look shriveled, lightly mist the storage medium with water to add a touch of humidity. If you spot any soft spots or fuzzy mold, remove the affected rhizome immediately so the problem doesn't spread to the rest of the batch.
Winter Storage Checklist:
- Lift rhizomes after the first frost kills the foliage.
- Cure for 2-3 days in a dry, protected area.
- Pack in a breathable container with peat or sawdust.
- Store at 40-50°F and check monthly for rot or shriveling.
Troubleshooting Common Care Questions
Even with the best care, you might occasionally run into a few questions about your cannas. Most issues are easily solved by adjusting one of the basic care steps.
Why are my cannas not blooming?
The most common reason for a lack of flowers is a lack of sunlight. If your cannas are in a spot that gets mostly shade, they will focus all their energy on leaves. Another common cause is planting too late; if the rhizome didn't get enough "heat units" early in the season, it might not have enough time to reach the blooming stage before fall. Finally, ensure you are fertilizing regularly, as a lack of nutrients can stall flower production.
What about pests?
Cannas are generally quite hardy, but they can occasionally attract slugs and snails, especially when the plants are young and the leaves are close to the ground. These pests like to chew holes in the foliage. You can manage this by keeping the area around the base of the plants clear of debris or using organic slug bait. In some southern regions, "canna leaf rollers" (caterpillars) may appear. If you see leaves that are zipped shut with silk, simply unroll them and remove the caterpillar by hand.
Why are the leaves turning yellow?
If the leaves are turning yellow in the middle of the summer, it could be a sign of over-watering in soil that doesn't drain well, or it could be a nutrient deficiency. Check the soil moisture—if it's soggy and smells "off," reduce watering. If the soil is fine, try a fertilizer with a bit of iron or magnesium to green up the foliage.
Conclusion
Caring for canna bulbs is an incredibly satisfying part of the gardening year. From the excitement of seeing those first pointed shoots emerge in late spring to the towering, tropical display of mid-summer, these plants truly earn their keep in the garden. By focusing on the basics—plenty of sun, consistent moisture, and regular feeding—you can create a stunning backyard oasis that feels worlds away.
Remember that gardening is a journey, and each season offers a chance to learn more about what your plants love. Whether you choose the classic green-leaved varieties or the striking variegated types like ‘Tropicanna’ or 'Phasion', the effort you put into their care will be rewarded with months of vibrant color. We hope these tips help you feel confident as you tend to your cannas this year.
Next Steps:
- Check your local frost dates to plan your planting time.
- Prepare your garden beds with compost to give your rhizomes the best foundation.
- Trust Longfield Gardens for high-quality rhizomes to start your tropical garden.
"Gardening with cannas is about embracing the bold. These plants aren't shy, and with just a little bit of consistent care, they will become the most talked-about feature of your summer landscape."
FAQ
Do I have to dig up my canna bulbs every year?
This depends on your location. If you live in USDA hardiness zones 7 to 10, you can usually leave your cannas in the ground year-round, provided you cover them with a thick layer of mulch. In colder zones (Zone 6 and lower), the ground freezes deep enough to kill the rhizomes, so you must dig them up and store them indoors for the winter.
How much water do cannas actually need?
Cannas are water-loving plants and prefer soil that is consistently moist but not swampy (unless you are growing specific water-canna varieties). In typical summer weather, a deep watering once or twice a week is sufficient for plants in the ground. For cannas in containers, you will likely need to water every day, as pots dry out much faster than the garden soil.
Can I grow cannas from the seeds that form after blooming?
Yes, you can, but it requires patience. Canna seeds have a very hard coat and usually need to be "scarified" (nicked with a file) and soaked in water before planting. Seed-grown cannas often take two years to flower and may not look exactly like the parent plant. For most gardeners, it is easier and faster to grow them from rhizomes or by dividing existing clumps.
When is the best time to divide my canna rhizomes?
The best time to divide cannas is in the spring before you replant them, or in the fall right after you lift them from the ground. Use a clean, sharp knife or simply pull the clumps apart with your hands. Ensure that every divided piece has at least one or two "eyes" (growth nodes), as these are necessary for the plant to send up new stems.