How to Build a Container Water Garden

Reader Contribution by Susan Melgren and Web Editor
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As the weather warms up and we turn our attention to outdoor living, now is the time to spruce up your porch or patio for spring and summer. A container water garden will enhance any outdoor living room and is relatively easy to assemble and maintain. Most water plants are tough to kill, and because the plants are just planted in submerged pots, it’s easy to rearrange your water garden if you get bored with your initial design.

Photo By la fattina/Courtesy Flickr

Selecting a Container

If it holds water, then it will probably hold a water garden. With their short, wide openings and rustic look, half barrels are popular vessels for a container water garden, but ceramic pots work well, too. An unsealed terra cot pot will seep water (especially if it has drainage holes in the bottom!), so if you’re going to use one, be sure to coat the inside with a nontoxic waterproof sealant. If you’re going to use an old wood vessel and are concerned about toxins seeping into the water and plants, line the inside with a pond liner.

Keep in mind that once the vessel is full of water, it’s going to be heavy, so pick a durable material.

Water Plants

When selecting water plants, look for plants with variety that will group well together. If you’re going to have a tall, spiky plant, pair it with a soft, cascading one for contrast and some floating lilies for a splash of color. Remember to scale the size of the plants to the size of the container; small plants will be dwarfed by a half barrel, while large plants spilling out of a small vessel will look crowded and chaotic. It’s likely that your water garden will be viewed from multiple angles, so keep that in mind when designing and arranging. If you plan to place your container water garden against a wall or in a corner place the tallest plant at the center of the back to create an appealing backdrop for the other plants to rest against. If the garden will be in full view, place the tallest plant in the center, and build around it.

Some popular water plants include:

Curled pondweed
Fairy moss
Floating heart
Soft rush
Spotted calla
Sweet flag
Umbrella palm
Underwater arrowhead
Variegated manna grass
Variegated spider lily
Velvet leaf
Water hyacinth
Water lettuce
Water lily
Water snowflake
Water violet
Willow moss
Yellow water buttercup

Water lilies shade the water in container water gardens, helping to prevent the growth of algae. Photo By Nicky Jacobs/Courtesy Fotolia.

Placing Your Water Garden 

Before you begin constructing your container water garden, select the location you’d like it to go. Once filled with water, the garden will be too heavy to move easily, so it’s best to start construction where the garden will eventually be. Select a location that receives full sun for at least five to six hours a day, with partial shade in the afternoon.

Putting Your Container Water Garden Together

Marginal plants, such as sweet flag and water snowflake, grow along the edge of the water in ponds and streams. Because they prefer shallow water, you may need to build a “shelf” for these plants out of bricks or upturned smaller containers if your vessel is too deep. Unlike true aquatic plants, marginal plants need a bit of soil to survive. To keep your potted plants sunk–and to prevent soil from escaping the pots and muddying up your container water garden–fill the top of the plants’ pots with pea gravel.

When arranging and “planting” your water plants, make sure the leaves are above the water line. (Unless, of course, you’re planting submerged plants such as willow moss or parrot’s feather, which like to be completely underwater.)

Water Garden Maintenance

To help control algae in your container water garden, be sure to include a few floating plants like water lilies or water lettuce. Floating plants shade the water from the sun, preventing the growth of algae. Both floating and submerged plants derive their nutrients directly from the water, which takes nutrients away from algae, helping to keep the water clean. If you’re concerned that your container water garden will be a mosquito breeding ground, try overfilling the container to wash away any mosquito larvae.

Although the water in your garden does not need to be changed on a regular basis, you may need to top the water off to replace that lost from evaporation.

Unless you live in a warm climate, you may need to dismantle your water garden for winter. Bring the plants inside and store them in a tub of water in the basement or other cool place.

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