Table of Contents
- Introduction
- The Natural Connection Between Cannas and Water
- Choosing the Right Variety for Your Pond
- Preparing Canna Rhizomes for Water Planting
- How to Plant Cannas in a Pond
- Sunlight and Warmth Requirements
- Feeding and Maintenance for Water Cannas
- Managing Growth and Space
- Overwintering Aquatic Cannas
- Common Scenarios: Growing Cannas in Water
- Why Some Cannas Don't Bloom in Water
- Encouraging a Long Bloom Season
- Summary of Water Canna Success
- FAQ
Introduction
Imagine the striking, tropical foliage of a canna lily rising elegantly from the edge of a backyard pond. These plants are famous for their bold colors and tall, architectural stems, making them a favorite for sunny garden beds. However, many gardeners are surprised to learn that these beauties are also quite comfortable with "wet feet." Adding them to your water features can transform a simple pond into a lush, vibrant oasis.
At Longfield Gardens, we enjoy helping people discover how versatile these plants truly are. Whether you are a seasoned pond owner or just starting out with a few containers, cannas are a wonderful choice for adding height and drama. They are naturally adapted to damp environments and can thrive in water if you follow a few simple steps.
This article explains how to successfully grow canna lilies in water, which varieties work best, and how to care for them throughout the season. You will learn the best ways to plant them in a pond setting and how to keep them healthy year after year. Growing cannas in water is an achievable goal for any gardener looking to add a splash of the tropics to their home.
The Natural Connection 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 the tropical and subtropical regions of the Americas. In these areas, they often grow in wetlands, along riverbanks, and in marshy ditches. They are naturally "marginal" plants, which means they prefer to grow in the shallow water found at the edges of ponds or lakes. If you're planning ahead by region, the Hardiness Zone Map is a useful reference.
While most people plant them in dry land garden beds, cannas have a unique biology that allows them to thrive in saturated conditions. Their thick, fleshy underground stems, called rhizomes, act like energy storage tanks. These rhizomes are tough and can handle being submerged in water as long as the water is warm and the plant is actively growing.
When you grow them in water, you are simply leaning into their natural preferences. They are excellent at filtering nutrients from the water, which can even help keep a pond cleaner. This makes them a functional and beautiful choice for anyone looking to enhance a water feature.
Choosing the Right Variety for Your Pond
While almost any canna can handle moist soil, some are specifically bred for life in the water. These are often referred to as "water cannas" or Canna glauca hybrids. These varieties tend to have more slender leaves and a more graceful habit than their land-based cousins.
At Longfield Gardens, we find that both traditional and water-specific varieties can succeed in a pond environment. However, if you are new to aquatic gardening, starting with a variety known for its vigor is a great first step. For a colorful, proven option, Canna Tall Tropicanna is a standout choice.
Water-Loving Canna Varieties
The most common aquatic cannas usually feature solid green or blue-green leaves and delicate flowers. They are specifically adapted to stand in several inches of water all summer long. These plants often have a more refined look that fits perfectly with the soft edges of a water garden.
Terrestrial Cannas in Water
You can also grow the large-flowered, broad-leafed varieties typically found in garden beds. Many gardeners have great success moving their favorite red, orange, or yellow cannas into the water. The key is to make sure the plant has already started growing before you submerge it. Land-dwelling varieties may need a little more time to adjust to having their roots underwater than the specialized water types.
Preparing Canna Rhizomes for Water Planting
The secret to success with aquatic cannas is timing. Because these are tropical plants, they love warmth. If you place a dormant rhizome into cold water, it may sit there without growing or even begin to break down. Instead, you want to wait until the plant is awake and ready to grow.
A simple way to get started is to pot the rhizomes in soil first. This gives the plant a chance to develop roots and a few leaves in a controlled environment. Once the weather is warm and the plant has several inches of green growth, it is much easier for it to transition to a life in the pond.
Key Takeaway: Always start your cannas in a pot of soil first. Wait until they have a few leaves and the weather is consistently warm before moving them into your pond or water feature.
Steps for Getting Started:
- Plant your rhizomes in a pot with standard potting soil in early spring.
- Keep the soil moist and place the pot in a warm, sunny spot indoors or in a greenhouse.
- Wait until the plant is at least 6 to 10 inches tall.
- Once the outdoor water temperature stays above 60°F, you can move the plant into the pond.
How to Plant Cannas in a Pond
Planting in water is a bit different than planting in a garden bed. You won't be digging a hole in the ground; instead, you will be using containers that sit on "shelves" within your pond. This allows you to control the depth and make it easier to move the plants when winter arrives. For broader seasonal timing, see the Shipping Information.
Choosing a Container
Use a sturdy plastic pot that is at least 10 to 12 inches wide. It is often best to use a pot without drainage holes or a specialized aquatic basket. If you use a pot with holes, you can line it with a piece of burlap or landscape fabric to keep the soil from washing out into your pond water.
The Right Soil for Aquatic Planting
Avoid using standard potting mixes that contain perlite or vermiculite. These materials are very light and will float right out of the pot, making a mess of your pond. Instead, use a heavy garden soil or a specialized "aquatic planting media." Heavy clay soil is actually ideal for this because it stays put and provides a solid anchor for the tall stems.
Setting the Depth
In a pond, depth refers to the amount of water sitting over the top of the pot. For most cannas, the ideal depth is between 1 and 6 inches. This means the top of the soil should be no more than 6 inches below the water's surface.
If your pond is deeper than this, you can use bricks or overturned pots to create a pedestal for your canna. This keeps the crown of the plant at the right level while allowing the tall foliage to reach toward the sun.
Sunlight and Warmth Requirements
Cannas are sun-seekers. To get the best flowers and the most vibrant leaf colors, they need plenty of direct light. This is especially true when they are growing in water. Aim for at least 6 to 8 hours of full sun every day.
In a pond setting, the water can actually help the plant stay warm during the day. However, if your pond is in a very shaded area, the cannas may grow tall and "leggy" as they reach for the light, and they may not produce as many blooms. If you have a shady pond, consider placing your cannas in the sunniest corner possible.
The temperature of the water is also important. Cannas won't do much growing until the water warms up in the late spring or early summer. Don't be discouraged if they seem to grow slowly at first; once the summer heat hits, they will take off rapidly. For more background on temperature and plant performance, visit Understanding Cold Hardiness and Heat Tolerance.
Feeding and Maintenance for Water Cannas
Even though they are growing in water, cannas are heavy feeders. They need plenty of nutrients to produce those massive leaves and bright flowers. In a garden bed, you might use a granular fertilizer, but in a pond, you have to be more careful.
Fertilizing Safely
The easiest way to feed aquatic cannas is by using fertilizer tablets or spikes designed specifically for pond plants. You simply push these into the soil near the roots. This keeps the nutrients concentrated where the plant can reach them and prevents the fertilizer from leaching into the pond water, which could cause an algae bloom.
Feed your cannas about once a month during the peak growing season. This ensures they have the energy to keep blooming until the first frost.
Routine Care
Maintenance for water-grown cannas is very similar to land-grown ones.
- Deadheading: When a flower stalk has finished blooming, cut it back to just above the next leaf. This encourages the plant to send up new flower spikes.
- Cleaning foliage: If any leaves turn yellow or brown, trim them off. This keeps the plant looking tidy and prevents decaying organic matter from falling into the pond.
- Monitoring for pests: Keep an eye out for slugs or aphids. While they are less common in the middle of a pond, they can still find their way to the leaves.
Managing Growth and Space
Cannas are vigorous growers. In a single season, a small rhizome can turn into a large, dense clump. When they are grown in water, they often grow even faster because they never have to worry about a lack of moisture. If you're growing more than one plant, the How Far Apart Should You Plant Canna Bulbs? guide can help you plan space.
If you notice that your canna is starting to look crowded or the pot is bulging, it might be time to divide it. However, most gardeners find that one division per year is plenty. It is usually easiest to divide them in the spring before you put them back into the pond.
If you are growing them in a gravel bog—a shallow area filled with rocks rather than soil—the roots will spread out through the gravel. This is a great way to filter pond water, but be prepared to thin the plants out every few years to keep them from taking over the entire space.
Overwintering Aquatic Cannas
In most parts of the United States, cannas cannot survive the winter if they are left in a pond. If the water freezes, the rhizomes will likely turn to mush. Since they are tender perennials, you need to bring them indoors before the first hard freeze.
Lifting the Plants
When the temperatures start to drop in the fall and the foliage begins to look a bit tired, it’s time to move them. Lift the pots out of the pond and let them drain for a day or two in a shady spot. This makes them much lighter and easier to handle.
Preparation for Storage
- Cut the stems down to about 2 to 4 inches above the soil line.
- Remove the clump from the pot and gently wash away the heavy pond soil or gravel.
- Let the rhizomes dry out in a frost-free area (like a garage or basement) for a few days until the surface feels dry to the touch.
Storage Conditions
Store the clean rhizomes in a box filled with slightly damp peat moss, perlite, or wood shavings. You want to keep them cool but not freezing—somewhere between 45°F and 55°F is perfect. Check on them once or twice during the winter to make sure they aren't completely dried out. If they look shriveled, a light misting of water will help. More detailed seasonal advice is covered in How to Dig Up and Store Canna Bulbs: A Winter Guide.
Key Takeaway: Bringing cannas indoors for winter is a simple process that ensures you can enjoy the same plants year after year. Think of it as a short winter nap for your tropical favorites.
Common Scenarios: Growing Cannas in Water
The Container Pond
If you don't have a full-sized pond, you can still grow cannas in water using a "patio pond" or a large decorative container without drainage. Simply place your potted canna inside a larger, water-filled pot. This is a perfect solution for balconies or small patios. It provides the tropical look of a water garden in a very small footprint. For container-grown plants, see How Many Canna Bulbs Per Container?.
The Gravel Bog
Some gardeners prefer to grow cannas in a bog filter. This is a shallow area where pond water is pumped through a bed of gravel. The cannas are planted directly into the gravel without any soil. This is a very effective way to remove excess nutrients from the pond. In this scenario, the plants rely entirely on the nutrients in the water to grow. They often grow very tall and sturdy in these conditions.
Moving from Land to Water
If you have a canna in your garden bed that you want to move to your pond mid-summer, you can! Dig it up carefully, wash the garden soil off the roots, and repot it in heavy clay or aquatic soil. Give it a few days in a bucket of shallow water in a shady spot to adjust before placing it into the full sun of the pond.
Why Some Cannas Don't Bloom in Water
If your canna is growing plenty of green leaves but no flowers, there are usually two main reasons: light and food.
Cannas in water need even more sun than those in the ground to trigger blooming. If the plant is in a spot that only gets 4 hours of sun, it will focus all its energy on leaves. Moving it to a sunnier spot usually solves the problem within a few weeks.
The second reason is nutrition. Growing in water can wash away nutrients quickly if you aren't using a slow-release fertilizer designed for aquatic use. If your plant looks healthy but won't bloom, try adding an extra aquatic fertilizer tablet to the pot.
Encouraging a Long Bloom Season
To get the most out of your water cannas, try to provide a consistent environment. Fluctuating water levels can sometimes stress the plant, so keep your pond topped up during the heat of the summer.
Also, remember that cannas are tropical. They love the humidity that naturally occurs around a body of water. This humidity helps keep their leaves lush and prevents the edges from drying out or "scorching" in the hot sun.
What to do next:
- Choose a sunny spot in your pond with a shallow shelf (1-6 inches deep).
- Purchase a few healthy canna rhizomes in early spring.
- Start them in pots of soil indoors to get a head start on the season.
- Move them to the pond once the water is warm and enjoy the tropical display!
Summary of Water Canna Success
Growing canna lilies in water is a rewarding way to add vertical interest and vibrant color to your garden. These plants are naturally suited to wet environments and are surprisingly easy to care for once you understand their basic needs. By choosing the right container, using heavy soil, and providing plenty of sunlight and food, you can enjoy a tropical paradise right in your own backyard. To browse a curated selection, visit the Canna Assorted Collection.
Remember that while they love the water, they still need the same warmth and care as any other canna. Providing them with a "head start" indoors and protecting them from the winter cold are the two most important steps for long-term success.
At Longfield Gardens, we believe that gardening should be a fun and creative experience. Experimenting with different ways to grow your favorite plants—like putting cannas in a pond—is a great way to discover what works best for your unique space. If you want to learn more about our promise to gardeners, see Our Guarantee.
"Cannas are the bridge between traditional gardening and water gardening. Their ability to adapt to aquatic life makes them one of the most versatile plants for any landscape."
We are here to support you with high-quality rhizomes and practical advice. With a little bit of sun and some "wet feet," your cannas will be the highlight of your summer garden.
FAQ
Can I use any type of canna lily in my pond?
Yes, most canna lilies can grow in water, but some are better adapted for it than others. The Canna glauca hybrids, often called water cannas, are the most reliable for staying submerged. Standard garden cannas can also thrive in a pond if you start them in soil first and wait until they are actively growing before placing them in the water.
How deep should I place my canna lily pot in the water?
The ideal depth for a canna lily is between 1 and 6 inches of water over the top of the pot. This keeps the rhizome and the base of the stems submerged while allowing the plant to remain stable. If the water is too deep, the plant may struggle to stay upright or may not get enough oxygen to its roots.
Do canna lilies in water need soil, or can they grow in just gravel?
Cannas can grow in either soil or gravel. In a traditional pond pot, using heavy clay or aquatic soil is best because it provides plenty of nutrients. In a bog filter or a gravel-based water feature, cannas can grow in just gravel, as they will pull the nutrients they need directly from the pond water.
Why is my water-grown canna lily not flowering?
The most common reasons for a lack of flowers are insufficient sunlight and a lack of nutrients. Cannas need at least 6 to 8 hours of direct sun to bloom well. Additionally, because they are heavy feeders, they often require monthly applications of aquatic fertilizer tablets to sustain their growth and flower production throughout the summer.