Planning and Installing a Water Garden

Space requirements and zoning must be considered when planning a water garden. Ample space must be left for any borders, benches, or surrounding landscapes. In some localities, zoning ordinances may require homeowners to erect a fence around a deep pool.

If you plan to install a water garden yourself, gather together a pick, shovel, heavy rope or garden hose, one or two straight boards, a spirit level, stakes for excavation, and a framing square. Bring in a supply of builders sand to line the excavation or underliner. Estimate one ton per 40 square feet of surface. Purchase border materials (such as stone or brick) and water-treatment supplies. Other things you may need are a submersible pump and electric cable, a fountain or waterfall with necessary accessories (such as a permanent pipe), and special lights or color fixtures to illuminate the pool at night. You may wish to wait until the pool is complete and the water pH and temperature adjusted before purchasing your plants and fish.

One or two people can install a water garden that will last for years. The key is careful planning before digging any soil. When choosing the location of a water garden, the gardener should consider placing it so it can be viewed and appreciated through a window in the house.

Other important factors to consider are exposure to sunlight, drainage, and proximity to trees. Water lilies and lotus need full sun at least five hours and, preferably, as much as ten hours a day. A shadier spot limits your choice of aquatic plants. A spot providing mid- to late-afternoon shade is preferable. Soil in the site should be well drained. Water-logged soil can distort the shape of an artificial pool and crack or break the liner. A pool placed in sandy or crumbly soil needs to be specially prepared to prevent caving-in of the sides. If the pond is directly under trees, leaves that fall into the pond can decay and harm fish and plant life, as well as clog pumps and filters.

Accessibility to electricity and water is an important consideration. The pool is filled with tap water from a garden hose, but occasionally needs to have water added due to evaporation. An electrical pump recirculates water for fountains and waterfalls and operates on a normal household current.

When deciding on pond depth, remember that shallow ponds are quicker to cloud with excess algae. Submerged plants, floating plants, and fish do better in deeper pools. A good, average depth is 18 to 24 inches, possibly deeper in colder climates.

There are three ways to create a pool for your water garden. FLEXIBLE PLASTIC LINERS are lightweight and inexpensive and can be cut to any shape. However, installation is more time consuming than for molded pools. PREFABRICATED FIBERGLASS POOLS are considerably more expensive, but more durable. Generally, pre-fab pools are better on sloping grounds or fresh fill. A CONCRETE POOL (properly installed) lasts the longest. Since inadequate mixing or reinforcement can cause immediate cracking, a professional installation is recommended for concrete.

If installing a liner or pre-fab pool, the steps are similar. First, outline the pond with a heavy rope, staking it at intervals. If installing a pre-fab pool, place the pool on the ground and outline as above, but make it 2 inches wider in every direction than the actual pool.

Next, dig a hole the exact shape of the pool, adding 2 inches to the depth to accommodate a layer of sand. When digging for a liner pool, create a shallow, "boggy" area for plants by digging a 9- to 12-inch-wide shelf along the perimeter. When digging for a pre-fab pool, follow the contours of the shell, including any built-in shelves. Clear the hole of rocks, smooth the soil, and level the top edges to make sure the installed liner will be camouflaged.

Line the excavation with about 2 inches of damp sand to prevent punctures, and smooth it down. (Some suppliers carry liner underlay that can be used instead of sand. Some liners can be used with carpeting.) Center the liner over the hole, and push it outward into the corners. Fold the liner into pleats where it bunches at curves and corners, and anchor it around the edge with stones or bricks. As the pool fills with water, smooth out folds and wrinkles. Shut off the water when it covers the liner evenly to the top on all sides. Trim away the surplus liner, leaving about 6 inches around the edge. Cover this flap with stones, bricks, tiles, or other paving materials.

Pre-fab shells may have to be lowered into the hole and then removed several times to get the edges of the hole even. Once the shell is in place, fill the pond slowly. Backfill around the shell with soil as the water level rises to ensure the walls are adequately supported by soil. Hide the edges of the shell with flagstones or tiles that overlap the edge by 1 or 2 inches.

Before stocking a water garden, the water should be prepared. If the water contains ordinary chlorine, wait 24 to 48 hours to allow the chlorine to evaporate. If chloramine or chlorine dioxide are present, ask a water garden or fish supply house for ounteractive chemicals.

by Ellen S. Bennett