Water gardens can be created in any sunny spot - whether it's a large suburban garden, a small city lot or a sunny balcony. Preformed rigid tubs are available that can be sunk in the ground, or placed on a balcony, while the more adventurous can excavate a free form shape and line it with a flexible PVC pond liner. Today's liners are flexible membranes that do not rot, and are frost-resistant and impermeable to roots. Their long life makes the pond permanent yet it can be removed and reused, making it entirely portable.

Flexible pond liners permit many shapes: rectangular, square, round or free-form. The liner is draped loosely over the excavated hole. Bricks or stones are placed on the overlap. As the pond is filled with water from a hose, the stones are eased off at intervals to allow the liner to fit snugly into the contours. Creating a pond that is at least three feet deep in the centre will allow you to over-winter hardy water lilies. Adding ledges of different depths around the pond's edge will accommodate other water plants, including those that prefer shallow water.

The edge of the pond can be finshed with rock or patio slabs. In addition to the main water plants, add snails, goldfish and oxygenating plants to create an algae- and insect-free, self-sustaining life system. Additional features that can be added are a submersible pump with a fountain head, and underwater lighting. Trees, shrubs and evergreens can be planted around or near the pond, but do not place them so that they create shade. The water surface should receive full sun all day.

Water lilies are easily grown, requiring only sunlight, rich soil and quiet, shallow water. Their flowers are among the most beautiful of all plants. If you have a spot that receives six hours of full sun, you can grow water lilies. Even apartment dwellers can have a tub or half barrel, if the balcony has a southern exposure.

All aquatic plants must be placed at their preferred depth. Hardy water lilies need 20 to 30 cm (8 to 12 inches) of water over the crown of the plant. Tropical water lilies prefer a depth of 15 to 20 cm (6 to 8 inches).

Hardy water lilies are perennial flowering plants, equally at home in natural or constructed ponds or pools, in tubs or half barrels. Dwarf varieties are particularly suitable for small containers. In large ponds hardy water lilies will naturalize and take no special winter care. Small ponds should be covered with boards and a heavy layer of straw, so that very little freezing takes place and the plants over-winter in natural conditions. Tub cultured plants should be removed in their pots to a cool basement and kept covered with wet burlap. Keep them moist over the winter.

Tropical water lilies should not be planted out until June, when danger of frost is past. Water temperature must be at least 20° C. Cold water will shock them into dormancy. If you wish to save these exotic plants, they must be lifted from the pond when cold weather arrives, washed off and taken indoors. You can simply winter-store the complete root system in moist soil in a warm room, or propagate more lilies by cutting off the small tubers attached to the larger ones, and storing them in clean, damp sand. If the entire root system is stored, some of the large tubers will rot, but enough should remain for replanting in the summer. If saving only the small tubers, take them out of storage in April and plant them in sandy soil in shallow water at about 20° C (72° F) in full sun. When leaves appear in two or three weeks, pot each tuber individually in good soil and place the pots an inch below the waters surface until outdoor planting time. This over-wintering by propagation is how it is done at the nursery but it is really practical only in a heated greenhouse.