University of Vermont Extension 
Department of Plant and Soil Science

Summer News Article 

Water Gardening

By Dr. Leonard Perry, Extension Professor
University of Vermont

 
The soothing sound of a waterfall or cascade down rocks, or of a fountain lighted at nighttime; the beauty of a small pond with water lilies. These are some of the ways water can add beauty and a peacefulness to gardens.

On a larger scale, you can create a water garden by digging a pond or small pool. For a large variety of plants, you should make the pond a minimum of about two feet deep and four to six feet across. Once the hole is dug, line it with two to three inches of sand, with a PVC pool liner on top. Black plastic can be used, but use a thick grade and several layers. The sand keeps the bottom of the liner from contacting rocks and being punctured.

On top of the liner you can place thick black felt pond liner. This felt keeps washed river stone, which you may then wish to add, from puncturing the liner from the top. If you're going to add a pond pump, underwater lighting, fountains, or blocks for your pots, now is the time. Many of these supplies can be found at local home and garden supply stores, larger garden centers, or from mail order sources (look for their ads in garden magazines).

Finish the edge of the pond with bricks or flat stones, such as slate, for a more formal effect. Simply lay these around the pond, over the edge of the liners. Native stones placed irregularly will give a more informal edge. Just make sure they are stable.

Tub gardens can be created from whiskey barrel halves, lined with plastic or rigid liners made especially for this purpose. Old plastic trash cans, halves of plastic drums, large ceramic pots, and metal or plastic cattle troughs are other sources of tub gardens. Attractive barrels may be left on the ground, or the less attractive ones sunk about level with the surface. If sinking, keep the edge a few inches above the ground to keep soil from washing into the pond.

I have a whiskey barrel half near the house, with an underwater light on a timer for nighttime. Not only is it attractive after dark, but it adds security lighting to my house.

To get the desired effect, you will need to sink your aquatic plants, in pots, in the water. Depending on the plants, you can place them at various heights by means of different size concrete blocks placed underneath them. Or when digging a pond, create stepped terraces as various levels.

Water lilies, for instance, might be placed a foot below the water's surface. Place oxygenating grasses on the bottom. Place other perennials in pots just below the water's surface.

Algae growth is one of the few problems in tub gardens and is seen as green growth in the water. This often happens in the spring and early summer with higher light and warmer temperatures. Once you achieve a balance of enough plants, and perhaps when other life is established, the water should clear. The other life includes tadpoles or snails.

If algae forms blankets, remove it with a notched stick of piece of rough wood. Poke it into the mass, twist it, and then draw it to the side and out. A filtration system, as in pools, can help remove free-floating algae.

Soil for water plants consists of two parts ordinary garden soil and one part well-rotted cow manure. If available, use equal parts garden soil and pond muck (the soil from the bottom of a pond). If neither muck nor manure is available, add a handful of bonemeal per bucket of soil. Avoid more fertility as this will only increase the algae. Once planted, line the top two inches of the pot with sand or washed gravel. This helps prevent algae growth.

Most pots can be used for containers but should be large enough for the plants grown. Special wooden pots (cedar or cypress), perforated plastic cages, or mesh baskets are often used.

Some water plants withstand freezing but most don't. Even the hardy water lilies will survive if in large ponds below the ice, but not if frozen. For most smaller water features in the North, bring the pots of lilies and water plants indoors for the winter.

In late fall remove the containers of plants, cleaning off the old leaves and dead foliage. If you won't be putting them back into tubs of water indoors, let the pots drain overnight. Then place in plastic bags left open at the top.

Move aquatic plant pots to a garage or cellar where they won't freeze, with temperatures between 32 to 35 degrees F. Keep moist, not letting them dry out, over winter. Place them back outdoors in spring, once hard freezes are over, then sit back and watch your water garden grow!


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