Can You Grow Cannas in a Pond?

Table of Contents

1. Introduction
2. The Relationship Between Cannas and Water
3. Choosing the Right Canna for Your Pond
4. How to Plant Cannas in an Aquatic Environment
5. Essential Care: Sun, Water Depth, and Heat
6. Fertilizing Cannas in a Pond
7. Managing Tall Varieties and Wind
8. Seasonal Transitions and Overwintering
9. Conclusion
10. FAQ

Introduction

Adding a splash of tropical color to your water feature is one of the most rewarding ways to elevate your backyard landscape. If you have ever admired the bold, architectural leaves and vibrant blooms of cannas, you might have wondered if these sun-loving plants can survive with their roots submerged. The short answer is a resounding yes. At Longfield Gardens, we have found that cannas are surprisingly adaptable, often performing even better in a pond or bog setting than they do in a traditional garden bed.

This guide is designed for home gardeners who want to bring that lush, oasis-like feel to their ponds, water gardens, or low-lying wet areas. We will cover which varieties work best, the simple steps for planting them in an aquatic environment, and how to keep them thriving all season long. By understanding a few basic principles of water gardening, you can enjoy these spectacular flowers in a whole new way. Cannas are versatile "marginal" plants that can bridge the gap between your garden soil and your water feature with ease.

The Relationship Between Cannas and Water

To understand why cannas do so well in water, it helps to look at where they come from. Most canna species are native to tropical and subtropical regions of the Americas, where they often grow along the edges of marshes, riverbanks, and wetlands. Because of this ancestry, they have a natural affinity for "wet feet," which means they are perfectly comfortable having their roots constantly moist.

In the gardening world, we often categorize plants by their moisture needs. Cannas fall into a unique category because they are equally happy in a well-drained garden border or a shallow pond. When grown in water, they function as "marginal plants." These are plants that grow in the shallow areas around the edges of a pond, with their roots and the base of their stems underwater while their foliage and flowers reach up into the air.

Growing cannas in a pond offers several benefits. The constant access to water ensures the plants never suffer from drought stress, which often leads to larger leaves and more frequent flowering. Additionally, cannas are excellent at absorbing excess nutrients from the water, such as nitrogen and phosphorus. This helps naturally filter your pond and can reduce the growth of unwanted algae, making the water clearer and healthier for fish and other aquatic life.

Choosing the Right Canna for Your Pond

While almost any canna can adapt to a water environment, some are specifically bred for it. These are often referred to as "aquatic cannas" or "water cannas." One of the most famous groups is the Longwood series, developed at Longwood Gardens. These hybrids were created specifically to thrive in standing water and are known for their blue-green foliage and elegant flowers.

However, you do not have to limit yourself to specific aquatic hybrids. Many of the popular varieties we carry at Longfield Gardens, including the striking ‘Tropicanna’ with its striped foliage or the classic ‘The President’ with its bold red blooms, will grow beautifully in a pond. When choosing a variety, consider the scale of your water feature.

Compact and Dwarf Varieties

For smaller ponds or container water gardens, dwarf cannas are an excellent choice. These typically grow between 2 and 3 feet tall. Because they are shorter, they are less likely to catch the wind and tip over, which can be a challenge with taller plants in floating or submerged pots. They provide the same tropical look without overwhelming a small space.

Tall and Giant Varieties

If you have a large pond or a dedicated bog area, taller varieties that reach 4 to 6 feet can create a stunning backdrop. These larger cannas have massive, paddle-like leaves that provide a sense of privacy and drama. Giant varieties like ‘Musifolia’ are grown primarily for their incredible foliage, which can look almost like banana leaves, adding a prehistoric feel to the water's edge.

Foliage Colors

Cannas offer more than just flowers; their leaves are a design element in their own right. You can choose from solid green, deep burgundy, or variegated patterns with stripes of yellow, orange, and red. In a pond setting, these colors are often reflected in the water, doubling the visual impact of your planting.

Key Takeaway: While specific water hybrids exist, most garden cannas will thrive in a pond as long as they are transitioned correctly. Choose dwarf varieties for stability in small ponds and tall varieties for a dramatic backdrop in larger water features.

How to Plant Cannas in an Aquatic Environment

Planting a canna in a pond is slightly different than planting one in the ground. You cannot simply drop a bare rhizome into the water and expect it to grow. The plant needs a stable base and the right type of soil to prevent it from floating away or clouding the water.

Step 1: Select the Right Container

Use a sturdy plastic pot with drainage holes. A 2-gallon or 5-gallon pot is usually sufficient, depending on the size of the rhizome. If the holes in the pot are very large, you can line the bottom with a piece of landscape fabric or burlap to keep the soil from washing out. Some gardeners prefer using "aquatic planting baskets," which have a fine mesh that allows water to flow through while keeping the roots and soil contained.

Step 2: Use Heavy Soil

This is one of the most important steps. Do not use standard potting mix. Most commercial potting soils contain perlite or vermiculite, which are lightweight volcanic minerals designed to improve aeration. In a pond, these materials will float out of the pot and create a messy film on the surface of your water.

Instead, use a heavy garden soil or a specialized aquatic planting medium. A soil with a high clay content is ideal because it stays put and provides the minerals cannas need. If your backyard soil is a heavy clay, it will actually work perfectly for this purpose.

Step 3: Planting the Rhizome

Fill your pot about two-thirds full with the heavy soil. Place the canna rhizome on the surface, making sure the "eyes" or growing points are facing upward. Cover the rhizome with about 1 to 2 inches of soil. Press the soil down firmly to remove any large air pockets.

Step 4: Add a Gravel Cap

To prevent fish from digging in the soil and to keep the soil from floating away, add a 1-inch layer of pea gravel or small river rocks on top of the soil. This "cap" keeps everything tidy and adds a bit of weight to the pot, which helps prevent it from tipping over in the wind.

Step 5: The "Wake Up" Period

Before placing your canna in the pond, it is best to let it start growing in a traditional way. Place the potted rhizome in a warm, sunny spot and keep the soil moist but not submerged. Once the plant has sent up a few inches of green growth and the weather is consistently warm, it is ready to go into the water.

What to do next:

• Pick a pot that is at least 10–12 inches in diameter.
• Source heavy clay-based soil rather than standard potting mix.
• Plant the rhizome with eyes facing up and cover with soil.
• Apply a layer of gravel to the top of the pot.
• Wait for the first leaves to appear before submerging the pot in the pond.

Essential Care: Sun, Water Depth, and Heat

Cannas are sun-worshippers. To get the best growth and the most vibrant flowers, your pond should be located in a spot that receives at least 6 to 8 hours of direct sunlight every day. If the area is too shady, the plants may become "leggy," stretching toward the light, and they may fail to bloom.

Managing Water Depth

When placing your pot in the pond, depth is key. Cannas are marginal plants, not deep-water plants like water lilies. They prefer to have their "feet" wet, but they do not want to be completely submerged.

A good rule of thumb is to place the pot so that the top of the gravel is between 1 and 6 inches below the surface of the water. If your pond has built-in planting shelves, these are the perfect spot. If your pond is deeper, you can use bricks or overturned pots to create a pedestal for your canna pot to sit on.

The Importance of Water Temperature

Cannas are tropical plants that love heat. They will not start growing vigorously until the water temperature reaches at least 65°F to 70°F. In many parts of the country, the air warms up much faster than the water.

If you put your cannas in the pond too early in the spring while the water is still chilly, the rhizomes may sit dormant and can eventually rot. It is always better to wait until the water is warm to the touch before moving your plants into their aquatic home. If you live in a northern climate, this might mean waiting until June to move them into the pond.

Fertilizing Cannas in a Pond

Cannas are "heavy feeders," meaning they require a lot of nutrients to produce those massive leaves and tall flower spikes. In a garden bed, you might use a granular fertilizer or compost. In a pond, you have to be a bit more strategic to ensure the fertilizer reaches the plant roots and doesn't just feed the algae in the water.

Using Aquatic Fertilizer Tablets

The best way to feed cannas in a pond is with specialized aquatic fertilizer tablets or spikes. These are designed to be pushed deep into the soil inside the pot. Once buried, they slowly release nutrients directly to the root zone over several weeks or months.

Push one or two tablets into the soil every month during the peak growing season (usually June through August). Because the fertilizer is buried in the heavy soil and topped with gravel, it stays where the plant needs it. This targeted feeding keeps your cannas lush and blooming without causing an explosion of string algae in the pond water.

Nutrient Absorption from the Pond

While you should provide supplemental fertilizer, remember that cannas are also working as a natural filter. They will pull fish waste and decaying organic matter from the water and convert it into plant growth. This is why cannas often look so healthy in ponds—they have a constant "buffet" of nutrients available to them.

Managing Tall Varieties and Wind

One of the most common challenges when growing cannas in a pond is the wind. Because cannas have large, sail-like leaves and can grow quite tall, a strong gust of wind can easily tip over a pot sitting on a narrow shelf.

Increasing Stability

To prevent tipping, use a wide-based, heavy pot. Adding extra rocks to the bottom of the pot before adding the soil can also help lower the center of gravity. If your pond has a liner, be careful that the edges of the pot or the rocks are not sharp, as you don't want to accidentally puncture the pond's waterproof seal.

Strategic Placement

Place your taller cannas in areas where they are somewhat protected from the strongest winds, perhaps near a fence or a taller shrub on the pond's edge. You can also group several pots together. This not only creates a more impactful visual display but also allows the plants to support one another.

Choosing Dwarf Varieties for High-Wind Areas

If you live in a particularly breezy area, dwarf varieties are your best friend. Because they stay low to the water's surface, they have much less "drag" and are far more stable. They still offer the same beautiful flowers and tropical foliage but without the stress of having to upright a fallen pot after every summer thunderstorm.

Key Takeaway: Stability is the main challenge for tall cannas in water. Use heavy pots, sink them on stable shelves, and consider dwarf varieties if your pond is in an open, windy location.

Seasonal Transitions and Overwintering

Cannas are hardy in USDA zones 8 through 11. In these warmer regions, they can often stay in the pond year-round. They may die back to the water level during a brief cold snap, but the rhizomes will usually survive and sprout again in the spring. If you want to check your own climate before planting, the USDA hardiness zone map is a helpful place to start.

However, for most of the United States (zones 3 through 7), cannas will not survive the winter if left in the water. The ice and freezing temperatures will turn the rhizomes to mush. Fortunately, overwintering them is a simple process that allows you to enjoy the same plants year after year.

When to Move the Plants

As the temperatures drop in the fall and the first frost blackens the foliage, it is time to take action. Remove the pots from the pond and let them drain for a day or two. Cut the stems back to about 2 or 3 inches above the soil line.

Storing the Rhizomes

You have two options for storage:

1. Store in the Pot: If you have space in a cool, frost-free basement or garage (ideally between 40°F and 50°F), you can simply store the entire pot as is. Keep the soil slightly damp—just enough so the rhizome doesn't shrivel—but not wet.
2. Lift and Clean: Many gardeners prefer to remove the rhizomes from the pots, wash off the soil, and let them air dry for a day. You can then store them in a box filled with slightly damp peat moss, perlite, or wood shavings.

In the spring, when the danger of frost has passed, you can divide the rhizomes if they have become too large for their pots. This is a great way to get more plants for free! Start them in fresh soil, let them wake up in a sunny spot, and return them to the pond once the water has warmed up again.

Conclusion

Growing cannas in a pond is a wonderful way to bring a touch of the tropics to your home landscape. These resilient plants thrive with "wet feet," providing bold textures, vibrant colors, and natural water filtration. Whether you choose a dwarf variety for a small container pond or a towering giant for a large water feature, the process is straightforward and the results are spectacular.

By getting the basics right—choosing a sunny spot, using heavy soil, and waiting for warm water—you can ensure your cannas will be the stars of your summer garden. At Longfield Gardens, we love how cannas can transform a simple pond into a lush, flowering escape. With just a little bit of seasonal care, these plants will reward you with beauty and elegance year after year.

Final Steps for Success:

• Always wait for warm water (65°F+) before placing cannas in your pond.
• Position pots on shelves so the water depth is no more than 6 inches above the soil.
• Feed your plants with aquatic fertilizer tablets once a month during summer.
• Bring the rhizomes indoors before the first hard freeze if you live in a cold climate.

Explore our selection at Longfield Gardens to find the perfect colors and sizes for your water garden, and enjoy the ease of growing these tropical favorites. For seasonal shipping details, see Shipping Information, and learn more about Longfield Gardens’ 100% Quality Guarantee.

FAQ

Can I grow any variety of canna in my pond?

Most garden cannas will adapt well to life in a pond as long as they are grown as marginal plants with only their roots and the base of their stems submerged. While specific "water cannas" are exceptionally vigorous in water, popular terrestrial varieties like those with bronze or variegated foliage also perform beautifully in shallow water. For more growing basics, visit Garden Basic Essentials.

How deep should I submerge my canna pots?

Cannas prefer shallow water, usually between 1 and 6 inches deep over the top of the pot. If the water is too deep, the stems may struggle to breathe and can eventually rot. If your pond is deep, use bricks or a submerged stand to raise the pot to the appropriate level near the surface.

Do I need special soil for cannas in a pond?

Yes, you should avoid standard potting mixes because they contain lightweight ingredients like perlite that will float out and clutter your pond. Use a heavy, clay-based garden soil or a specialized aquatic planting medium that will stay at the bottom of the pot and provide a stable base for the roots.

Will cannas in a pond harm my fish?

Cannas are safe for pond fish and are actually quite beneficial for them. They help clean the water by absorbing excess nutrients that would otherwise fuel algae growth, and their underwater roots provide a hiding place for small fish. Just be sure to use a layer of gravel on top of the soil to prevent fish from digging and creating cloudy water.