The Water Garden (cont)
By: Robert Smaus
Building a Water Garden
Depth. The ideal depth is about 18 inches. In many communities, that's also the legal depth. Any deeper, and some building codes consider it a swimming pool, which might mean that it must be fenced and that you'll need a permit to build it.
An aboveground water garden can be shallower than 18 inches. For years, I used half whiskey barrels, after carefully swelling the slats shut by filling and refilling the barrel halves with water. I then graduated to 2 1/2-foot-wide concrete pots with plugged drainage holes, but the pots were only about a foot deep, the minimum for many aquatics. I managed to grow small water lilies and other aquatics and keep a few goldfish.
My current pool is 18 inches deep but above the ground, so visitors can sit along its edge.
Lining. You can also excavate an inground pool and use a special pond liner made of polyvinyl chloride (PVC) or ethylene propylene diene monomer (EP rubber). Or, build a pond out of materials such as railroad ties, and line the inside. Some nurseries stock liners and preformed ponds that you simply bury. Or, you can order materials by mail.
Planting a Water Garden
Where to find plants. Once you have the pond, shop for plants. Many nurseries carry them only in the summer, but many mail-order sources are also available. Suppliers' catalogs have information about installing a garden, pond-making supplies, snails, and plants. However, if you know someone with a water garden, you can probably get all of your plants free. They multiply quickly, and every spring, gardeners compost many divisions.
Containers. Most aquatics grow best when planted in wide, shallow containers that you submerge in the pond. I use old plastic nursery cans and cheap plastic washtubs. Water lilies' containers must be about 18 inches wide and 10 inches deep. Plants with shorter stems and smaller root systems can grow in smaller containers. Unlike aboveground containers, these pots don't need drainage holes. If the pots have any, cover them with two layers of newspaper so soil doesn't leak out. (Newspaper takes years to decompose under water; even pulp pots last a long time, like the timbers of a sunken ship.)
Soil. Forget what you've learned about potting soils. Avoid regular potting mixes and soil amendments. They contain elements that will rot, pollute, or float. Aquatics grow best in containers filled with ordinary garden soil. The heavy clay garden soil that you regularly curse over is fine for aquatic plants. Dig some up, and break up clods to use it as aquatic potting soil.
Some people cover the soil with sand or pebbles to keep it from muddying the water and to prevent fish like koi from digging up the plants. I don't. After planting, I simply soak the soil in the container and then set the container in the pool. It's heavy enough not to float, and the water clears in about a day.
Fertilizer. At planting time, add a little aquatic-plant fertilizer, especially for lilies. Cover the fertilizer with soil, or it will escape and feed the pond's algae. I use tablets made for aquatic plants, and place them next to the roots.