How to Make a Container Water Garden

Think outside the garden bed and use a container water garden to experiment with plants that add new textures and colors to your yard's palette. It takes only an afternoon to set up a container water garden, but it can transform your backyard.

Almost any sealed container that holds water can become a container water garden. If you're starting out a 15- to 25-gallon container hits the sweet spot in terms of size and portability. Most importantly, ensure the container is waterproofed and glazed inside and outside. A pot that isn't properly sealed will leak and cause a mess.

The smallest possible water garden is 1 quart, but something this size will typically only support one aquatic plant. The smaller your container, the more often it will need to be topped up as water evaporates.

Do not use a container made of metal. As the metal oxidizes, it can release chemicals and minerals that may kill your aquatic plants.

Choose a spot for your container garden before setting up the garden. Once the pot is filled with water and plants, it will be heavy and difficult to move. For example, a 20-gallon container weighs more than 200 pounds once it's filled.

Place the empty container in an area that:

Receives a minimum of six hours of sun every day.  Most aquatic plants need full sun to thrive and blossom.

Provides sufficient support. The larger the container, the more support it needs. Decks and balconies may not be able to support the weight of the water garden. For the sturdiest foundation, consider keeping container water gardens at ground level.

Can be accessed easily. You should be able to easily view and enjoy your new water garden, and also get to it to do regular maintenance, such as water top ups.

Fill the container with water and you're ready to plant.

You have many possibilities when it comes to water gardening and plant choices. The number of plants needed to fill the water garden depends on your container size. For the healthiest garden, aim to cover two-thirds of the water surface with plants -- no more and no less. Sufficient plant coverage helps minimize the risk of algae blooms, but overcrowding can reduce plant health.

You have many options when it comes to aquatic plants, including:

Water hyacinth (Eichhornia crassipes) grows in U.S. Department of Agriculture plant hardiness zones 9 through 11.

Water lettuce (Pistia stratiotes, USDA zones 8 through 10)

Water fern (Azolla filiculoides, USDA zones 7 through 10)

Common duckweed (Lemna minor, USDA zones 4 through 10).

These plants grow as perennials in their zones and as annuals elsewhere.

Many aquatic plants are invasive in some areas, especially those with warm climates. This includes water hyacinth and water lettuce. If they're invasive in your area, don't plant them.

For aquatic plants that like to free float, simply release them onto the surface of the water. For plants that prefer to be rooted and submerged, put each plant's roots into an aquatic plant basket -- available from most garden stores or nurseries -- and fill the pot with heavy, clay-based garden loam or a specialist aquatic soil. Cover the surface of the loam with pea gravel, which locks the soil in place and keeps it from floating. Place the pot into the water so the crown of the plant is just below the water's surface. If your pot is too deep in the water, use bricks or large rocks to bring the pot closer to the water's surface.

One of the most common mistakes beginners make is to use too many plants, which can result in a messy, chaotic and visually unappealing appearance. Water gardens look their best when just a handful of simple plants are used. Two or three different kinds of plants is often more than enough variation.

Every water garden shares several common care requirements:

Top up the water garden every few days as the water evaporates, keeping the water at the same level it was when you first set up the garden. 

Add aquatic fertilizer once the plants show signs of new growth, following the specific fertilizer's labeled guidelines.  For potted aquatic plants, use a fertilizer tablet, such as a 10-12-8 product, pushed into each individual plant's pot once or twice a month. For floating aquatic plants, add a liquid aquatic fertilizer, such as 1 tablespoon of 0-0-3 fertilizer for every 30 gallons of garden water twice a month.

Scoop out and remove fallen debris or dead vegetation. Decaying plants add excess nutrients to the water and may provoke an algae bloom.