Table of Contents
- Introduction
- The Secret to Canna Growth: The Rhizome
- Finding the Best Location for Growth
- Timing the Planting for Success
- Step-by-Step: How to Plant Canna Rhizomes
- Water and Nutrition: Feeding the "Big Eaters"
- Managing Growth Throughout the Summer
- How Do Cannas Grow in Containers?
- Overwintering: What Happens When the Growth Stops?
- Dividing Cannas for More Plants
- Troubleshooting Common Growth Issues
- Designing Your Garden with Cannas
- Conclusion
- FAQ
Introduction
There is a unique kind of excitement that comes with watching a canna lily unfurl its first giant leaf. One day you have a quiet corner of the garden, and the next, you have a towering, vibrant spire that looks like it belongs in a tropical rainforest. At Longfield Gardens, we love how these plants bring immediate drama and energy to any landscape, regardless of whether you live in a warm climate or a northern state.
Cannas are known for their bold foliage and exotic flowers, but for many gardeners, the way they grow remains a bit of a mystery. These plants are not typical perennials that grow from seeds or fibrous roots; they have a specific growth habit that relies on warmth, moisture, and a specialized underground structure.
In this guide, we will explore the fascinating journey of how cannas grow, from the moment you plant their dormant rhizomes to the peak of their summer bloom. Whether you are a beginner looking to add some height to your flower beds or an experienced gardener wanting to refine your technique, we are here to help you succeed. Understanding the simple basics of canna growth ensures your garden stays lush and colorful all season long.
The Secret to Canna Growth: The Rhizome
To understand how cannas grow, you first have to look beneath the surface. Unlike many flowers that grow from round bulbs, cannas grow from rhizomes. A rhizome is a thick, fleshy underground stem that grows horizontally. It acts as the plant’s energy warehouse, storing the nutrients and moisture needed to produce those massive leaves and bright flowers.
When you hold a canna rhizome, you will notice small bumps or points known as "eyes." These are the growth nodes. Each eye has the potential to become a new stalk. This is why the quality of the starting material is so important. A larger, plump rhizome with three to five eyes will naturally produce a fuller, more robust plant than a smaller one with only one or two eyes.
As the rhizome settles into warm soil, these eyes "wake up" and begin sending shoots upward toward the light and roots downward to anchor the plant. Because the rhizome grows horizontally, cannas naturally expand outward over time, creating beautiful, dense clumps of foliage. This growth habit makes them excellent for filling large spaces or creating a living privacy screen during the summer months.
Key Takeaway: Cannas grow from horizontal underground stems called rhizomes. The "eyes" on these rhizomes are the starting points for every stalk you see above ground.
Finding the Best Location for Growth
Cannas are high-energy plants, and they need the right environment to fuel their rapid development. Because they are native to tropical and subtropical regions, they have very specific preferences when it comes to sunlight and soil.
The Power of Sunlight
Sunlight is the primary fuel for canna growth. For the best results, you should plant your cannas in a spot that receives full sun. In gardening terms, this means at least six to eight hours of direct, unfiltered sunlight every day.
If cannas are planted in too much shade, they will still grow, but they may become "leggy." This means the stems grow extra long and thin as they reach for the light, which makes them more likely to flop over. Additionally, the vibrant colors of variegated or bronze-leaved varieties are much more intense when the plants get plenty of sun. If you have a particularly hot climate, cannas can handle a little afternoon shade, but they generally prefer as much light as you can give them.
Soil and Drainage
While many plants prefer soil that dries out between waterings, cannas are a bit different. They thrive in consistently moist, nutrient-rich soil. In the wild, some species even grow at the edge of ponds or in boggy areas.
However, "moist" does not mean "stagnant." We recommend planting them in soil that is rich in organic matter, such as compost or well-rotted manure. This helps the soil hold onto moisture while still allowing the roots to breathe. If your soil is very heavy clay and stays soggy like a puddle, it is a good idea to amend it with compost to improve the structure.
Protection from the Wind
Because cannas produce such large, broad leaves, they can act a bit like sails in the wind. In very windy areas, the leaves can become shredded or "ragged" along the edges. While this doesn't usually hurt the health of the plant, it can diminish the tropical look. If possible, plant your cannas near a fence, a wall, or a cluster of other sturdy plants to give them a little bit of a windbreak.
Timing the Planting for Success
One of the most important rules for how cannas grow is that they are heat-lovers. They have no tolerance for frost and will not begin to grow until the environment is warm.
The best time to plant canna rhizomes is in the late spring, once the danger of frost has completely passed and the soil has warmed up. A good rule of thumb is to wait until the time you would normally plant tomatoes in your garden. For most areas, the soil temperature should be at least 60°F. If you are planning your shipping window, our shipping information page explains how orders are scheduled by hardiness zone.
If you live in a northern climate with a short growing season, you don't have to wait for the weather to catch up. You can give your cannas a head start by planting the rhizomes in pots indoors about four to six weeks before the last frost date. Place the pots in a warm, sunny window or under grow lights. By the time the weather is warm enough to move them outside, you will already have established plants ready to take off.
What to do next:
- Check your local frost dates to determine the safest planting time.
- If you want earlier blooms, prepare some large pots and starting mix for indoor growth.
- Use a simple soil thermometer to ensure the ground is at least 60°F before planting outside.
Step-by-Step: How to Plant Canna Rhizomes
Planting cannas is a straightforward process, but getting the depth and spacing right will set the stage for a successful season. We recommend following these simple steps to ensure your rhizomes have the best start.
- Prepare the Soil: Loosen the soil to a depth of about 10 to 12 inches. This makes it easier for the new roots to spread out and find nutrients. Mix in a few inches of compost to provide a slow-release food source.
- Position the Rhizome: Dig a hole about 2 to 3 inches deep. Lay the rhizome horizontally in the hole. Look for the "eyes" or growth points; ideally, these should face upward, but don't worry if you can't tell which side is which. The plant is smart enough to find the surface on its own.
- Spacing: Give your cannas room to breathe. Space larger varieties about 18 to 24 inches apart. If you are planting dwarf varieties, 12 inches is usually sufficient. This spacing ensures good air circulation, which helps keep the foliage healthy.
- Cover and Tamp: Fill the hole with soil and gently press down with your hands to remove any large air pockets.
- Initial Watering: Water the area thoroughly right after planting to settle the soil around the rhizome.
After planting, it can take two to three weeks for the first green shoots to poke through the soil. Cannas are a bit slow to start, but once they begin growing, they move incredibly fast. Patience in the first few weeks is key!
Water and Nutrition: Feeding the "Big Eaters"
Cannas are often described by gardeners as "thirsty and hungry." Because they grow so much biomass in a single season—sometimes reaching heights of 6 to 8 feet—they require a lot of fuel.
Deep Watering
Regular water is the secret to those lush, tropical leaves. If the soil stays too dry, the leaves may start to turn brown at the tips or lose their vibrant color. We recommend a deep soaking at least once a week. In the height of summer or during a heatwave, you may need to water every other day, especially if your cannas are growing in containers.
A simple way to tell if your cannas need water is the finger test. Stick your finger an inch or two into the soil. If it feels dry, it is time to water. Using a layer of mulch, such as shredded bark or straw, around the base of the plants can help hold moisture in the soil and keep the roots cool.
Fertilizing for Growth
Since cannas grow so quickly, they appreciate regular feeding. When you first plant them, adding compost to the soil provides a great foundation. Once they have sprouted and are about 6 inches tall, you can begin a regular fertilization schedule.
A balanced, slow-release fertilizer works well for most garden beds. If you prefer liquid fertilizers, applying a dose every two to four weeks will keep the plants vigorous. If you are growing cannas primarily for their foliage (like the dark-leaved or variegated types), a fertilizer slightly higher in nitrogen can help promote larger, greener leaves. If you want more blooms, a balanced formula is usually best.
Managing Growth Throughout the Summer
Once your cannas are established, they are relatively low-maintenance, but a little bit of attention will keep them looking their best until the first frost.
Deadheading for More Flowers
Cannas produce flowers on long spikes. Each spike usually has several buds that open in succession. Once a flower has faded, you can remove it to keep the plant looking tidy. This process is called deadheading.
When the entire flower spike has finished blooming, you can cut the stalk down to the next leaf or flower bud. This encourages the plant to put its energy into producing new flower spikes rather than creating seeds. By deadheading regularly, you can often keep your cannas blooming from mid-summer all the way through autumn.
Caring for the Foliage
Sometimes the lower leaves of a canna can start to look a little worn as the season progresses. This is perfectly normal. You can simply trim away any yellowing or damaged leaves at the base of the stem.
If a summer storm or high winds tear the leaves, you can also trim off the ragged edges with a pair of clean garden scissors. This doesn't hurt the plant and keeps that clean, architectural look that makes cannas so popular.
Key Takeaway: Regular watering and monthly feeding are the two most important tasks for canna care. Deadheading spent blooms keeps the plant focused on producing new flowers.
How Do Cannas Grow in Containers?
You don't need a large garden bed to enjoy the beauty of cannas. They grow exceptionally well in containers and can turn a patio or balcony into a tropical retreat. For more ideas, see our summer-blooming bulbs for containers collection.
When choosing a pot for a canna, remember that these plants have large, vigorous root systems. For a single standard-sized canna, we recommend a container that is at least 15 to 18 inches in diameter. Dwarf varieties can fit in slightly smaller pots. Ensure the container has drainage holes at the bottom so the roots don't sit in stagnant water.
Because pots dry out faster than the ground, you will need to water container-grown cannas more frequently. During the hottest part of the summer, this might mean daily watering. Similarly, the nutrients in the potting soil will be used up quickly, so a regular liquid fertilizer every two weeks is a good idea to keep the growth steady.
Overwintering: What Happens When the Growth Stops?
In USDA hardiness zones 9 and 10, cannas are perennials that can stay in the ground year-round. The foliage might die back after a light frost, but the rhizomes will stay alive underground and sprout again when the weather warms up.
However, for those of us in zones 3 through 8, cannas are treated as "tender perennials." This means they will not survive a freezing winter in the ground. You have two choices: you can treat them as annuals and plant fresh rhizomes every spring, or you can dig up the rhizomes and store them for the winter.
How to Lift and Store Rhizomes
If you want to save your cannas for next year, follow these simple steps once the first frost has blackened the leaves:
- Cut Back: Use garden shears to cut the stalks down to about 4 inches above the ground.
- Dig Carefully: Use a shovel or garden fork to gently lift the clump of rhizomes out of the soil. Be careful not to bruise or cut the fleshy roots.
- Clean: Shake off the excess soil. You don't need to wash them; in fact, keeping them a bit dry helps prevent rot.
- Cure: Let the rhizomes sit in a dry, shaded area (like a garage or shed) for a few days to "cure." This toughens the skin.
- Store: Place the rhizomes in a box or breathable bag filled with slightly damp peat moss, vermiculite, or even wood shavings.
- Environment: Store the box in a cool, dark place where the temperature stays between 40°F and 50°F. A basement or insulated crawlspace is usually perfect.
Check on your stored rhizomes once or twice during the winter. If they look shriveled, you can lightly mist them with a spray bottle. If any look soft or rotten, remove them immediately to keep the rest of the batch healthy.
Dividing Cannas for More Plants
One of the most rewarding parts of how cannas grow is that they are very generous. A single rhizome planted in the spring will often grow into a large clump by the end of the season.
Every two or three years, it is a good idea to divide these clumps. This prevents the plants from becoming too crowded and gives you "free" plants to move to other parts of your garden or share with friends.
The best time to divide cannas is in the spring before you replant them. Simply pull or cut the rhizome clump apart into smaller sections. Make sure each section has at least one or two healthy "eyes." Allow the cut ends to dry for a day before planting them back in the ground.
Troubleshooting Common Growth Issues
While cannas are generally very hardy and easy to grow, you might occasionally run into a few hurdles. Here is how to handle the most common ones with ease.
My Cannas Aren't Blooming
If your cannas have plenty of leaves but no flowers, the most common reason is a lack of sunlight. If they are in a shady spot, moving them to a sunnier location next year will usually solve the problem. Another possibility is that they were planted too late and didn't have enough time to reach maturity before the season ended. Starting them indoors can help in shorter-season climates.
Holes in the Leaves
If you notice the leaves are staying rolled up or have neat rows of holes in them, you might have "canna leaf rollers." These are small caterpillars that hide inside the leaves. You can often manage them by simply picking them off or using a gentle, organic garden spray recommended by your local extension office. Keeping the area free of debris at the end of the season also helps reduce the chances of them returning.
Yellowing Leaves
If the leaves are turning yellow and the plant looks stunted, it may be a sign of a nutrient deficiency or overwatering in soil that doesn't drain well. Try a balanced liquid fertilizer and check the moisture level of the soil. Remember, cannas like moisture, but they don't like to sit in a swamp of stagnant water.
What to do next:
- Observe your plants weekly for any changes in leaf color or texture.
- If you see pests, act early with simple manual removal.
- Ensure you are feeding your plants at least once a month during the peak growing months.
Designing Your Garden with Cannas
Because cannas grow so tall and bold, they offer endless possibilities for garden design. Here are a few ways we like to use them at Longfield Gardens to create a beautiful landscape. If you're planning a broader planting scheme, our spring-planted bulb collections can help you build a coordinated look.
The Back of the Border
Tall cannas are the perfect "backdrop" plants. Use them at the very back of a flower bed to provide a wall of green or bronze foliage. This creates a beautiful contrast for shorter, fine-textured plants like daisies, salvias, or ornamental grasses.
Living Privacy Screens
If you have a patio or a section of your yard that feels a bit too exposed, a row of cannas can create a lush, living screen in just a few months. Because they grow so densely, they provide excellent privacy throughout the summer and fall.
Focal Points
A single, large-leaved canna in a beautiful ceramic pot can serve as a stunning focal point on a porch or at the end of a garden path. Varieties with variegated leaves, such as those with yellow and green stripes, are particularly effective at drawing the eye and adding a sense of light to the garden.
Water Garden Accents
If you have a pond or a wet area where other plants struggle, cannas are a fantastic choice. They bring height and color to the water's edge and can even be grown in submerged pots in shallow water.
Conclusion
Understanding how cannas grow is the first step toward creating a vibrant, tropical-inspired garden that thrives all summer long. These resilient plants ask for very little—just warmth, plenty of water, and a bit of food—and in return, they provide some of the most dramatic displays in the plant world. From the curious horizontal growth of the rhizome to the towering spires of flowers, the lifecycle of a canna is a testament to the joy of gardening.
At Longfield Gardens, we want to help you feel confident in your garden. Whether you are planting your very first rhizome or dividing a prize-winning clump, remember that gardening is a rewarding journey of observation and growth. With a few simple steps, you can enjoy these spectacular blooms year after year.
- Sunlight: Aim for at least 6-8 hours of direct sun.
- Water: Keep the soil consistently moist, especially during heatwaves.
- Food: Feed with a balanced fertilizer once a month.
- Warmth: Only plant outdoors once the soil is 60°F or warmer.
"The architectural beauty and vibrant colors of cannas make them an essential addition for any gardener looking to add a touch of the tropics to their home."
Ready to start your own tropical oasis? We stand behind our plants with a 100% quality guarantee, ensuring your rhizomes arrive healthy and ready to grow. Happy planting!
FAQ
How long does it take for cannas to grow and bloom?
After planting the rhizomes in warm soil, you can expect to see the first shoots emerge in about two to three weeks. From that point, the plants grow very quickly. Most cannas will begin to produce their first flowers within 10 to 12 weeks of planting, and they will continue to bloom until the first frost.
Can cannas grow in the shade?
While cannas are tough enough to survive in partial shade, they really need full sun to reach their full potential. In the shade, they will produce fewer flowers, and the plants may become tall and floppy as they stretch toward the light. If you are growing them for their foliage, partial shade is acceptable, but full sun is always better for the most vibrant colors.
Do I have to dig up my cannas every winter?
This depends on your USDA hardiness zone. If you live in Zone 9 or 10, your cannas can stay in the ground year-round. In Zone 7 or 8, they may survive with a thick layer of mulch, but it is a bit of a risk. If you are in Zone 6 or colder, you must dig up the rhizomes and store them in a frost-free place if you want to keep them for the following year.
How much water do cannas actually need?
Cannas are much more water-dependent than many other garden perennials. They should never be allowed to dry out completely. A deep watering once a week is a minimum for in-ground plants; container-grown cannas may need water every day during the hot summer months. If the leaves look wilted or the tips turn brown, it is usually a sign they need more moisture.