Can Cannas Grow in Water? Tips for Aquatic Success

Table of Contents

1. Introduction
2. Understanding the Canna-Water Relationship
3. Choosing the Best Cannas for Water
4. How to Transition Cannas from Soil to Water
5. Potting Cannas for Aquatic Environments
6. Light and Temperature Requirements
7. Feeding Your Aquatic Cannas
8. Maintenance and Care for Water Cannas
9. Designing with Cannas in Water Features
10. Winterizing Your Water Cannas
11. Why Quality Matters
12. Conclusion
13. FAQ

Introduction

There is nothing quite like the lush, tropical feel that tall cannas bring to a summer garden. With their bold, paddle-shaped leaves and vibrant, exotic flowers, they transform any corner of the yard into a vacation-like retreat. While most gardeners think of these sun-loving plants as staples for garden beds and borders, many are surprised to learn that they are incredibly versatile.

At Longfield Gardens, we enjoy helping you discover new ways to showcase your favorite plants, and growing cannas in water is one of the most rewarding techniques to try. Whether you have a sprawling backyard pond or a simple decorative container on your patio, these plants can adapt beautifully to an aquatic lifestyle.

This guide will explain exactly how to grow cannas in water, from selecting the right varieties to ensuring they get the nutrients they need. You will learn the simple steps for transitioning these plants into a water environment so you can enjoy their towering beauty all season long. Growing cannas in water is a fun and easy way to add vertical interest and a splash of color to your water features.

Understanding the Canna-Water Relationship

Cannas are naturally moisture-loving plants. In their native habitats across tropical and subtropical regions of the Americas, they are often found growing along the damp edges of rivers, marshes, and wetlands. This natural history means they are biologically equipped to handle more water than many other common garden perennials.

In gardening terms, we often classify plants that can grow with their roots submerged as "marginal plants." This means they thrive in the transition zone between dry land and deep water. While they do not grow entirely underwater like a seaweed, they are perfectly happy having "wet feet." This flexibility is what makes them such an excellent choice for modern water gardens.

It is helpful to distinguish between growing in "wet soil" and growing in "standing water." Most cannas will thrive in a boggy area where the soil is constantly saturated. However, many varieties can also sit directly in a pond where the water level stays a few inches above the soil line. Understanding this distinction helps you choose the best spot in your yard for these stunning plants.

Choosing the Best Cannas for Water

While almost all cannas enjoy moisture, some are specifically bred or naturally better suited for life in a pond. When you are looking to add that tropical flair to a water feature, you have two main options: standard garden cannas and specialized aquatic hybrids.

Standard Canna Varieties

Many of the popular cannas we offer, such as those with bronze foliage or bright bi-color blooms, can be grown in water if they are acclimated correctly. These standard varieties are robust and adaptable. They typically reach impressive heights and produce large, showy flowers that stand out against a backdrop of water. If you already have cannas in your garden, you can often take a division and move it into a water setting with great success.

Aquatic Canna Hybrids

There is a specific group of cannas often referred to as "Longwood Hybrids" or "Water Cannas." These were specifically developed to thrive in aquatic environments. They tend to have a slightly different growth habit, often appearing a bit more slender and graceful than their land-based cousins. These varieties are highly resistant to the typical challenges of constant submersion, such as root rot, and they often bloom more prolifically in high-moisture settings.

Foliage and Flower Selection

When choosing a canna for your water garden, consider the visual impact of the leaves. Varieties with variegated or striped foliage look particularly striking when reflected in the surface of a pond. Similarly, dark purple or bronze leaves create a sophisticated contrast with the greens of other aquatic plants. Since water features often act as a focal point, selecting a variety with a bold color palette ensures your canna gets the attention it deserves.

Key Takeaway: Most cannas can grow in water, but specifically labeled "water cannas" are the most reliable for deep submersion. Start with healthy rhizomes from a trusted source to ensure the best performance.

How to Transition Cannas from Soil to Water

The most important secret to success when growing cannas in water is the transition. Moving a plant directly from a dry garden bed into a deep pond can be a shock to its system. To get the best results, it is best to follow a gradual process that allows the plant to adjust its root structure.

Start with an Actively Growing Plant

It is much easier to transition a canna into water once it has already started growing. Instead of placing a dormant rhizome directly into a pond, plant it in a pot with soil first. Keep the soil moist and wait until the plant has produced at least two or three healthy green leaves. This indicates that the root system is active and ready to take on the task of processing more water.

The Gradual Sink Method

Once your canna is growing well in its pot, you can begin moving it toward its final home in the water. Start by placing the pot in a shallow tray of water or a very shallow part of your pond. After a week or so, move it a few inches deeper. This slow change allows the roots to adapt to the lower oxygen levels found in submerged soil.

Why Acclimation Matters

Plants produce different types of roots depending on their environment. Soil-grown roots are optimized for finding moisture in the earth, while water-grown roots are designed to take in oxygen and nutrients from a liquid environment. By transitioning your cannas slowly, you give the plant time to develop the specialized roots it needs to thrive underwater.

• Step 1: Plant your rhizome in a container with standard garden soil.
• Step 2: Provide plenty of sun and keep the soil consistently damp.
• Step 3: Once the plant is 6–12 inches tall, place the pot in a shallow water basin.
• Step 4: After one week, move the pot into your pond or water feature.
• Step 5: Ensure the water level is no more than 2–6 inches above the soil surface.

Potting Cannas for Aquatic Environments

To grow cannas in water successfully, you need to use the right container and the right type of "soil." Standard potting mixes found at garden centers are often too light for water gardening. They contain perlite or peat moss, which will float out of the pot and create a mess in your pond.

Choosing the Right Container

Use a sturdy plastic pot that does not have drainage holes, or use a specific aquatic planting basket with a fine mesh. A 2-gallon to 5-gallon pot is usually sufficient for a single canna rhizome. Since cannas can grow quite tall, a heavier pot also helps prevent the plant from tipping over in the wind.

The Best Soil for Water Planting

The best "soil" for aquatic cannas is actually heavy garden soil or clay-based soil. This type of soil stays in the pot and provides a stable anchor for the heavy rhizomes and tall stalks. Avoid using any mix that contains organic "forest products" or lightweight fillers. If your backyard soil is heavy and contains a good amount of clay, it is likely perfect for this job.

Top-Dressing for Stability

Once you have planted your canna in the heavy soil, add a layer of pea gravel or small decorative stones on top. This layer serves two purposes: it keeps the soil from washing away into the water and it adds a finished, professional look to your water feature. The gravel also helps hold the rhizome in place while it establishes its new roots.

Light and Temperature Requirements

Cannas are sun-worshippers. This does not change just because they are growing in water. In fact, because water can reflect and intensify light, the placement of your aquatic canna is a key factor in how well it will bloom.

Sun Exposure

For the most vibrant flowers and the strongest stalks, place your water-grown cannas in a spot that receives at least six to eight hours of direct sunlight every day. If they are in a spot that is too shady, the plants may become "leggy," meaning they grow tall and thin as they reach for the light. They may also produce fewer flowers. If you notice your canna isn't blooming as much as you'd like, moving it to a sunnier part of the pond is an easy win.

Water Temperature

Cannas love warmth. They will grow much faster when the water temperature reaches 65°F to 70°F. In the early spring, the water in a pond can stay quite chilly, which might slow down the plant's initial growth. This is another great reason to start your cannas in pots on a sunny patio before moving them into the deeper, cooler water of a pond. Once the summer heat arrives, the warm water will act like a battery, keeping the plants happy and growing rapidly.

Protection from Wind

Because cannas can reach heights of five feet or more, they can sometimes be affected by strong winds. In a water garden, a tall plant acts a bit like a sail. If your pond is in a very open area, consider placing your cannas near a wall or a decorative fence that can act as a windbreak. Alternatively, grouping several pots together can help them support each other.

Key Takeaway: High light and warm water are the two biggest drivers of canna success. Position your water feature in the sunniest spot available for the best results.

Feeding Your Aquatic Cannas

Cannas are often called "heavy feeders," which simply means they require a lot of nutrients to produce those massive leaves and large flowers. In a traditional garden bed, they get these nutrients from the soil and supplemental fertilizer. In a water environment, managing their "food" requires a slightly different approach.

Using Fertilizer Spikes

The most effective way to feed cannas in water is to use slow-release fertilizer spikes. These are designed to be pushed deep into the soil inside the pot. Because they are buried, the nutrients go directly to the roots rather than dissolving into the pond water. This is important because too many nutrients in the pond water can lead to an overgrowth of algae, which can turn the water green.

Timing Your Feedings

Start fertilizing your cannas about a month after you move them into the water. In most climates, a single application of a balanced, slow-release fertilizer spike will last for the entire growing season. If you live in a region with a very long summer, you might consider a second feeding in mid-July to keep the blooms coming until frost.

Nutrient Balance

Look for a fertilizer that is balanced, meaning it has roughly equal parts of nitrogen, phosphorus, and potassium. Nitrogen helps with leaf growth, while phosphorus is essential for flower production. Following the package instructions for the size of your container is the best way to ensure your plants get exactly what they need without overdoing it.

Maintenance and Care for Water Cannas

One of the best things about growing cannas in water is that you never have to worry about watering them! However, they still benefit from a little bit of routine maintenance to keep them looking their best.

Deadheading for More Blooms

As the flowers on your canna begin to fade, you can remove the spent blooms. This process, called deadheading, encourages the plant to put its energy into producing new flowers rather than seeds. Simply snip the old flower stalk off just above the next set of leaves or buds.

Removing Old Foliage

Throughout the season, the lower leaves of the canna may naturally turn yellow or brown as the plant grows taller. This is perfectly normal. You can keep the plant looking tidy by trimming away these old leaves with a sharp pair of garden shears. This also helps improve air circulation around the base of the plant.

Managing Pests

Cannas are generally very healthy, but they can occasionally attract "canna leaf rollers," which are small caterpillars that roll themselves up in the leaves. In a water garden, you can often simply unroll the leaf and remove the caterpillar by hand. Keeping the area around your water feature free of debris also helps minimize pest issues.

Designing with Cannas in Water Features

The vertical height and architectural shape of cannas make them a designer's dream for water features. They offer a contrast to the flat leaves of water lilies and the fine textures of aquatic grasses.

Large Ponds and Lakes

In a large pond, cannas look best when planted in groups of three or five. This creates a bold mass of color that can be seen from across the yard. Place them in the "marginal zone" near the edge where the water is shallow. They serve as a beautiful backdrop for shorter aquatic plants like pickerel weed or marsh marigolds.

Small Patio Ponds

You don't need a massive pond to grow cannas in water. A simple whiskey barrel liner or a large glazed ceramic pot without a drainage hole can become a miniature water garden. Place one tall canna in the center and surround it with a few floating plants like water lettuce. This creates a high-impact, low-maintenance feature for a deck or patio.

Rain Gardens and Bog Areas

If you have a spot in your yard where water naturally collects after a rainstorm, cannas are an ideal choice. These "boggy" areas provide the consistent moisture cannas love without the need for a formal pond structure. They can help soak up excess water while providing a beautiful floral display.

• Height: Use tall varieties at the back of a pond and dwarf varieties in small containers.
• Texture: Pair the wide leaves of cannas with the feathery foliage of papyrus or horsetail.
• Color: Match the flower colors to your outdoor furniture or other blooming perennials for a cohesive look.

Winterizing Your Water Cannas

In most parts of the United States, cannas are not winter-hardy. This means they cannot stay in the water once the temperatures drop toward freezing. Fortunately, saving them for next year is a simple process.

When to Bring Them In

Wait until the first light frost has blackened the foliage. This signal tells the plant to go dormant and store its energy in the rhizome for the winter. Once this happens, lift the pot out of the water.

Cleaning and Storing

Cut the stalks back to about 2 or 3 inches above the soil line. You can then remove the rhizomes from the pot and wash off the heavy pond soil. Let them dry in a shady, well-ventilated spot for a day or two. At Longfield Gardens, we recommend storing the clean rhizomes in a box filled with slightly damp peat moss or vermiculite.

The Best Storage Environment

Store the box in a cool, dark, and frost-free place, such as a basement or crawl space. The temperature should ideally stay between 40°F and 50°F. Check on them once or twice during the winter to make sure they aren't getting too dry or too wet. In the spring, when the danger of frost has passed, you can start the process all over again.

Why Quality Matters

When you are investing time into creating a beautiful water garden, starting with high-quality plants makes all the difference. We work with experienced growers to ensure that the rhizomes you receive are healthy, vigorous, and true to variety.

Because aquatic environments can be more demanding than traditional garden beds, starting with a strong plant gives you a significant advantage. A healthy rhizome has the energy reserves needed to transition smoothly to water and produce a stunning display of flowers throughout the summer. We stand behind our plants with a 100% quality guarantee, so you can plant with confidence and enjoy the process of watching your water garden grow.

Conclusion

Growing cannas in water is a simple and rewarding way to bring a touch of the tropics to your backyard. By following the natural preferences of these moisture-loving plants, you can create a stunning aquatic display that requires very little daily maintenance. Remember to transition them slowly, provide plenty of sunlight, and give them a boost of nutrients to keep them blooming.

Gardening should be an enjoyable exploration of what is possible in your unique space. Whether you are adding a few pots to a small patio pond or creating a lush border around a large water feature, cannas are a versatile choice that rarely disappoints.

• Start early: Pot your cannas in soil first to get them growing before moving them to water.
• Use the right soil: Heavy garden soil or clay prevents messy water and provides stability.
• Provide sun: Aim for 6–8 hours of direct light for the best flower production.
• Feed correctly: Use fertilizer spikes buried in the pot to avoid algae blooms.
• Winterize: Lift and store rhizomes in a cool, dry place once the first frost arrives.

"Cannas are the ultimate multitaskers of the garden, offering incredible height, brilliant color, and a surprising ability to thrive in water. With just a few simple adjustments to your planting routine, you can enjoy these tropical beauties in entirely new ways."

We invite you to browse our selection of Canna Tall Tropicanna at Longfield Gardens and start planning your own aquatic oasis today. With a little bit of sun and some "wet feet," your cannas will be the highlight of your summer garden.

FAQ

Can I put regular cannas in my pond?

Yes, most standard garden cannas can grow in water as long as they are acclimated slowly. It is best to start them in a pot with soil and wait until they have several inches of green growth before submerging the pot in your pond. This gradual transition helps the plant adjust its roots to the aquatic environment without the risk of rot.

How deep should the water be for cannas?

Ideally, the water level should be between 1 and 6 inches above the surface of the soil in the pot. While cannas love "wet feet," they should not be planted so deep that the entire foliage is underwater. Keeping the crown of the plant near the water's surface ensures it gets enough oxygen while still benefiting from the constant moisture.

Do I need special soil to grow cannas in water?

You should avoid standard, lightweight potting mixes because they contain materials like perlite that will float out of the pot. Instead, use a heavy garden soil or a clay-based soil which stays put under the water. Adding a layer of pea gravel on top of the soil helps hold the rhizome in place and keeps the water clear.

Will cannas survive the winter in a pond?

In most regions, cannas cannot survive the winter if they are left in a pond that freezes. To save them for next year, lift the pots out of the water after the first frost has turned the leaves brown. Cut the stalks back, remove the rhizomes from the soil, and store them in a cool, frost-free place until spring.