Installing A Backyard Water Garden

The pond sides have a ledge where concrete blocks are set on top of the liner to hold it securely in place. Make sure the ledge is level.

Remove the sod from the pond area (or in this case, the sand and soil below it ). Dig out the pond. To make sure that the depth of the hole is consistent from one side to the other, pound a stake on each side of the hole, set a 2x4 on the stakes, and check to be sure it's level. Then measure down from the 2x4 to the floor of the hole in several locations. Dig out or fill back in until it's even.

Dig out a ledge around the sides deep enough for concrete blocks to be set on top of the liner, and make sure that it's level.

Pre-formed liners come in various shapes and sizes and are convenient and durable. The disadvantages are that you are restricted to certain sizes, shapes and depths, and the hole you dig must fit the liner exactly.

Selecting the Liner and Filling the Pond

A flexible liner conforms to nearly any shape and size and is also very durable. It can be purchased at garden centers and home supply stores and comes in various thicknesses, with thicker ones being more expensive. This project uses a liner that is 45-mil thick, a good balance of price and durability.

To determine what size liner you'll need, measure the length and width of the hole. If it is an oval or odd shape, measure at its widest point. Use this formula to determine the liner size:

(depth x 2) + width + 3 feet = width
(depth x 2) + length + 3 feet = length

This flexible pond liner is made of EPDM, which is more expensive than PVC or polyethylene but will last longer--probably 20 to 30 years.

The depth correlates to the sides of the pond. Adding 3 feet to the width and length is for overlap. This water garden is 8 feet wide, 8 feet long, and 3 feet deep, so following the formula, the liner is 6 (3 x 2) plus 8 plus 3 for overlap, for a total width of 17 feet. The length is the same.

Use a piece of old carpet as an underliner to pad the liner and prevent it from being punctured by things like sharp stones. Also cover the sides, using long nails to hold the carpet in place. Trim the excess with a razor blade knife.

Unfold the liner as you put it in the hole, making sure there is plenty overlapping on both sides. Smooth out the big wrinkles, and fold the corners for a neat appearance.

To keep the water in your pond from becoming stagnant, you need a pump. To figure out the size of pump, measure how much water your pond holds. Multiply the length x depth x width x 7.5 gallons (the amount in 1 cubic foot). Choose a pump that can recirculate one-third to one-half of the pond water every hour. For a waterfall or other feature, use a bigger pump.

All pumps come with a filter, but you can add a biological filter to extend the life of your pump, keep the water cleaner and maintain the proper biological ecosystem. While filling the pond with water, place the pump, biofilter and fountain into the pond on a plastic crate, in a corner of the pond to allow room for a few plants. A water bell fountain head allows water to flow smoothly over the top, like a mushroom. It attaches to the pump, and a riser pushes the water to the top.

Fill the pond about two-thirds full and adjust the folds and creases in the liner as the pond fills. Let the water sit for a few days so that any chlorine in the water dissipates. If you are anxious to introduce fish and plants right away, add a de-chlorinator to the water.

This tropical water lily, Nymphaea 'Terri Dunn', is blue--a color not available in hardy varieties.

Selecting Plants and Fish

There are so many fun and unusual plants you can grow in a water garden. One of the most popular is the water lily, which comes in hundreds of varieties. Lilies need to be submerged about 6 to 12 inches below the water surface. Submersible plants are natural oxygenators, giving off oxygen during the day and using oxygen at night. They are also a natural biofilter. There are two types of water lilies: hardy (to Zones 3 or 4) and tropical.

Marginal water plants are placed with the pot submerged in the water and the plant above the water surface.

Marginal plants also like to be in the water, but only their pot and 1 to 2 inches of their crowns are submerged. Marginal plants are good choices for the edge of a pond. There are also plants that simply float on top of the water and are easy to place and maintain. However, they sometimes need fertilizer.

Water lettuce is a common floating plant that is simply placed on the water surface.

Some good plant choices for a water garden include:
- water lily, which can last for years and blooms from spring through mid fall
- water lettuce, or shellflower, which has deeply creased lime-green leaves that resemble heads of lettuce (hardy only in Zones 9 and 10)
- cypress or umbrella plant, a vertical, marginal plant that does best in water that is only 4 inches deep (hardy in cold climates)

Goldfish are a colorful, fun addition to a water garden.

Goldfish and shubunkins, or calico goldfish, are popular and easy to care for. They grow up to 10 inches long and are quite hardy. To keep fish alive through the winter in climates where water freezes, keep a hole in the ice to allow oxygen to enter the water.

Once you've selected water plants and fish, they need to be transported home safely. First, keep them out of sunlight, which can heat them to dangerous temperatures. Keep plant leaves wet and fish completely submerged. For long trips, open the bag to allow fresh oxygen in every couple of hours.

Final Touches to the Water Garden

With the pond about three-fourths full, place blocks on top of the liner around the ledge. The liner goes behind the blocks and folds back over the top. Next, place the railroad ties or more rocks on top of the ledge.

Place pots of submerged plants on plastic crates to elevate them so that the surface of the soil is about a foot below the water. Fish will be able to swim between the holes in the crate.

While filling your pond, you need to acclimate the fish to their new environment. Do this by adding a little pond water to the bag that the fish come in — about 10 percent more than what's already in the bag, four times, waiting about 15 minutes between each time. Once the fish have had at least an hour to acclimate, set them loose in their new home. Don't feed them for the first few days so they get used to finding food on their own. After that you can supplement by adding food every couple of days or so.

Don't overload your pond with plants and fish. Water plants grow quickly and spread out, and fish will soon reproduce.

Another finishing touch you can add is a floating glass ball. These very popular garden ornaments reflect light as they float peacefully on the water.

Finally, plug in the pump and see how it works. This is an ambitious weekend project, but with a little planning and a helping hand, it's well worth the effort. You will enjoy your new water garden for years to come.