Table of Contents
- Introduction
- Understanding Water Cannas vs. Land Cannas
- Finding the Perfect Spot for Your Water Garden
- Starting Your Cannas: Timing and Preparation
- Step-by-Step Guide to Planting Cannas in Water
- Caring for Your Aquatic Canna Lilies
- Troubleshooting Common Issues
- Overwintering Cannas Grown in Water
- Designing with Water Cannas
- Realistic Expectations for Your Water Garden
- Conclusion
- FAQ
Introduction
There is something truly magical about the way canna lilies transform a space into a lush, tropical oasis. With their oversized, banana-like leaves and vibrant, jewel-toned flowers, these plants bring an undeniable energy to any landscape. While many gardeners are familiar with growing them in traditional flower beds, the discovery that you can grow canna lilies in water opens up a whole new world of design possibilities. Whether you have a backyard pond or a simple decorative container on your patio, these "water-loving" beauties thrive with their feet wet.
At Longfield Gardens, we believe that gardening should be a joyful and rewarding experience for everyone. Adding canna lilies to your water features is a fantastic way to enjoy high-impact color with surprisingly low maintenance. This guide will walk you through everything you need to know about selecting the right varieties, planting them effectively, and keeping them healthy throughout the season. By the end, you will feel confident and ready to bring a touch of the tropics to your own home.
Understanding Water Cannas vs. Land Cannas
The first step to success is understanding that while many canna lilies are adaptable, certain varieties are particularly well-suited for aquatic environments. In the gardening world, you will often hear about "water cannas" or "aquatic cannas." These are typically hybrids specifically bred to flourish in saturated soil or shallow water.
The most famous of these are the Longwood hybrids, developed at Longwood Gardens. These varieties, such as 'Erebus' (salmon-pink), 'Ra' (bright yellow), and 'Endeavour' (brilliant red), are celebrated for their ability to grow directly in water. They feature elegant, blue-green foliage that resists the common "burnt edge" look that some land cannas get when they are over-saturated.
That said, many "land" cannas can also adapt to water. Varieties with dark bronze or variegated foliage, like Tropicanna, often do remarkably well in boggy conditions. The key is how you introduce them to the water. A canna that has already started growing and has established a few leaves is much more likely to transition successfully into a water environment than a dormant rhizome placed directly into a pond.
Key Takeaway: While specific aquatic hybrids like the Longwood series are the gold standard for water gardening, many common canna varieties can thrive in water if they are started in soil first and moved into the water once they are actively growing.
Finding the Perfect Spot for Your Water Garden
Cannas are sun-seekers. To get those iconic, brilliant blooms, your plants will need plenty of light. This is the "right plant, right place" rule in action. When choosing a location for your water-grown cannas, aim for a spot that receives at least six to eight hours of direct sunlight each day.
If you are placing them in a pond, look for "marginal" areas. This refers to the shallow edges of a pond where the water is typically only 2 to 6 inches deep. These areas mimic the natural boggy habitats where wild cannas often grow. If your pond is deeper, you can still include cannas by placing their pots on submerged ledges or using "pond plant stands" to keep the crowns of the plants near the water's surface.
For those without a pond, cannas are excellent candidates for "container bogs." You can use a large, decorative pot without a drainage hole. This allows you to keep the soil constantly saturated, providing the "wet feet" that cannas love without needing a full-scale water feature.
What to do next:
- Identify a spot in your yard that gets 6+ hours of full sun.
- Check the depth of your pond edges or select a large, watertight container.
- Ensure the location is sheltered from heavy winds, as tall cannas can act like sails.
Starting Your Cannas: Timing and Preparation
One of the most important rules for growing cannas in water is that timing beats tricks. Cannas are tropical plants that love warmth. If you place a canna rhizome in cold, stagnant water in early spring, it is likely to rot before it ever has a chance to sprout.
We recommend starting your canna rhizomes indoors in pots about 4 to 6 weeks before your last expected frost. This gives the plant a "head start." By the time the weather warms up and your pond water reaches a consistent 60°F or higher, you will have a sturdy plant with several leaves ready to be moved into the water.
When you receive your rhizomes from us, they may already have small "eyes" or sprouts. This is a great sign of vitality! Plant them in a standard potting mix first, keeping the soil moist and warm. Once the danger of frost has passed and the outdoor temperatures are reliably warm, you can begin the transition to their permanent water home.
Step-by-Step Guide to Planting Cannas in Water
Planting in water requires a slightly different approach than planting in a garden bed. You need to ensure the plant stays upright and that the soil doesn't wash away into your pond.
1. Choose the Right Container
Use a heavy plastic nursery pot. A 3-gallon or 5-gallon size is usually best because cannas have vigorous root systems. Avoid pots with large side slits; you only want drainage holes at the bottom. The weight of a larger pot also helps prevent the tall stalks from tipping over in the wind.
2. Use the Correct Soil
This is a crucial step. Do not use standard potting soil that contains perlite or vermiculite. These materials are designed to be light and airy, which means they will float right out of the pot and create a messy film on your water's surface. Instead, use a heavy, "plain" garden soil. A soil with a high clay content is actually ideal for pond plants because it stays in the pot and provides a stable anchor for the roots.
3. Planting Depth
Place the canna (which should already be growing) into the pot and fill in around it with your heavy soil. Leave about an inch or two of space at the top. Top the soil with a layer of heavy gravel or river stones. This "mulch" of stones serves two purposes: it keeps the soil from washing away and it prevents fish (like koi) from digging in the dirt.
4. Submerging the Pot
Lower the pot slowly into the water. For most cannas, the water level should be about 2 to 4 inches above the top of the pot. It is perfectly fine if the crown of the plant is slightly submerged, but the majority of the foliage should be well above the water line.
Key Takeaway: Use heavy clay-based soil and top it with river rocks to keep your aquatic cannas stable and your water clear. Never use potting mixes with floating bits like perlite in a pond.
Caring for Your Aquatic Canna Lilies
Once your cannas are settled in the water, they are remarkably easy to care for. They won't need the daily watering that container plants usually require, but they do have a few specific needs to stay looking their best.
Feeding Your Plants
Cannas are "heavy feeders," meaning they need a lot of nutrients to produce those big leaves and bright flowers. In a pond environment, they will absorb some nutrients from the water and fish waste. However, to really see them thrive, we suggest using aquatic fertilizer spikes. These are specially formulated to release nutrients slowly into the soil without dissolving into the pond water and causing algae blooms. Simply push a spike into the soil of the pot once a month during the growing season.
Pruning and Deadheading
To keep your cannas blooming all summer long, practice regular deadheading. When a flower cluster fades, snip it off just above the next set of leaves. This encourages the plant to put its energy into new blooms rather than seed production. If a leaf becomes tattered or yellowed, simply cut it off at the base of the stem.
Managing Growth
Cannas grow fast! In a single season, one rhizome can fill a 5-gallon pot. If you notice the pot becoming "root-bound" or if the plant starts to lean heavily, it may need to be divided. Most water gardeners find that dividing their cannas once a year is the best way to keep them manageable.
What to do next:
- Insert an aquatic fertilizer spike every 4 weeks.
- Deadhead spent flowers to encourage new growth.
- Remove any yellowing or damaged leaves to keep the display tidy.
Troubleshooting Common Issues
Even though gardening should be stress-free, it is helpful to know what to look for if your plants aren't performing as expected. Most issues with water-grown cannas have very simple solutions.
The Plant is Tipping Over
This is the most common challenge with tall cannas in water. If your plant is falling over, it usually needs more weight at the base. You can place the pot inside a larger, heavier decorative ceramic pot (without drainage holes) submerged in the pond, or add more heavy river stones to the top. Alternatively, you can choose Canna Short Pink Magic varieties that stay under 3 feet tall, making them much more stable in windy conditions.
No Blooms
If your canna is all leaves and no flowers, it is likely a matter of sun or food. Ensure the plant isn't being shaded by nearby trees as the season progresses. If the sun is adequate, try increasing your fertilizer schedule. Remember, cannas need fuel to create those spectacular displays!
Holes in the Leaves
If you notice the leaves are being rolled up or have neat rows of holes, you might have "canna leaf rollers." These are small caterpillars that hide inside the unfurling leaves. The best approach is to simply look for the rolled leaves and remove the caterpillars by hand, or trim away the affected foliage. Keeping your garden clean and removing old debris at the end of the season helps prevent these visitors from returning next year.
Overwintering Cannas Grown in Water
In warmer climates (USDA Zones 8–10), cannas can often stay in the water year-round. They will go dormant in the winter, and you can simply cut the brown foliage back to the water line. They will sprout again once the water warms up in the spring.
For those of us in colder regions, cannas need a little winter nap indoors. Since they are tender perennials, they cannot survive a deep freeze.
- Lift the Pot: Before the first hard frost, remove the pot from the water.
- Cut Back: Trim the foliage down to about 4 to 6 inches above the soil.
- Drain: Let the pot sit in a shady spot for a few days to allow excess water to drain away.
- Store: You can either remove the rhizomes from the soil and store them in a box with damp peat moss or just bring the entire pot into a frost-free basement or garage. The goal is to keep them cool (around 40–50°F) but not freezing.
- Check Periodically: Give them a tiny splash of water every month or so to ensure the rhizomes don't completely shrivel up.
Key Takeaway: In cold zones, treating your water cannas like a summer vacationer—bringing them inside for the winter—ensures they will be ready to perform again next year.
Designing with Water Cannas
Growing cannas in water offers unique design opportunities that you just don't get in a traditional border. Because they grow so tall and upright, they provide excellent "architectural" height.
- The Centerpiece: Use a single large canna in a decorative "no-hole" pot as a focal point on a patio or at the end of a garden path.
- The Backdrop: Place a row of cannas along the back edge of a pond to create a living green wall that provides privacy and a sense of enclosure.
- Color Echoes: If you have a variety like 'Tropicanna' with orange-striped leaves, pair it with orange lilies or marigolds in nearby pots to create a cohesive color story.
Cannas also look fantastic when paired with other water plants. The broad, flat leaves of water lilies provide a beautiful horizontal contrast to the vertical, sword-like stalks of the canna. Adding a "filler" plant like creeping Jenny or water hyssop to the base of the canna pot can soften the edges and create a professional, layered look.
Realistic Expectations for Your Water Garden
While we want every garden to be perfect, it's important to remember that nature has its own pace. Your cannas might take a few weeks to "settle in" after being moved into the water. You might see a little bit of transplant shock where the oldest leaves turn yellow. This is perfectly normal! As long as the center of the plant is pushing out new, green growth, your canna is doing just fine.
The size and blooming frequency will also depend on your specific microclimate. A canna in a sunny spot in South Carolina will grow much faster than one in a shorter summer in Maine. Embrace the rhythm of your own garden and enjoy the process of watching these tropical giants reach for the sky.
Conclusion
Growing canna lilies in water is one of the easiest ways to add drama and exotic beauty to your outdoor space. By following a few simple steps—starting your plants early, using heavy soil, and providing plenty of sun—you can enjoy a spectacular display that lasts from midsummer right through the first frost. These plants are resilient, adaptable, and incredibly rewarding to grow.
- Start rhizomes indoors to give them a head start on the season.
- Use heavy, clay-based soil to keep pots stable in the water.
- Provide at least 6 hours of sun and regular aquatic fertilizer.
- Lift and store rhizomes indoors if you live in a cold climate.
At Longfield Gardens, we are here to help you succeed. Whether you are planting your first pond or adding to an established collection, canna lilies are a "must-have" for a vibrant summer garden. We invite you to explore the different colors and textures available and start your own tropical water garden today!
Growing cannas in water simplifies your gardening routine while maximizing the tropical impact of your yard, proving that sometimes the best way to grow is to dive right in.
FAQ
Can any variety of canna lily grow in water?
While most canna lilies can adapt to very wet or boggy soil, "water canna" hybrids like the Longwood series are specifically bred for aquatic life. If you want to use a standard garden variety, it is best to let it establish leaves in a pot of soil first before submerging it in a pond to ensure it transitions successfully.
How deep should I submerge my canna lily pots?
For most cannas, the ideal depth is between 2 and 6 inches of water over the top of the pot. This keeps the roots and the base of the plant saturated while allowing the foliage to stand tall above the water. If the water is too deep, the plant may become unstable or struggle to get enough oxygen to its crown.
What kind of soil should I use for cannas in a pond?
You should use a heavy, "plain" garden soil with high clay content. Avoid commercial potting mixes that contain perlite, vermiculite, or a high percentage of peat moss, as these light materials will float out of the pot and create debris in your pond. A layer of heavy gravel on top of the soil will help keep everything in place.
Do I need to fertilize my water-grown cannas?
Yes, cannas are very hungry plants! While they can get some nutrients from the pond environment, they will bloom much better if you use aquatic fertilizer spikes. These are designed to be pushed into the soil in the pot, providing a direct source of food for the plant without encouraging excessive algae growth in the surrounding water.