Water gardening, whether on a large or small scale, is one of the most enjoyable, fascinating and trouble-free, once initial construction and landscaping has been complete, forms of ornamental horticulture.
The attractiveness of a water garden extends over a long season. Few garden plants can compare with tropical water-lilies by providing a succession of flowers from June onwards until cut back by frost. These gardens lend themselves superbly to artificial illumination. Both the night-flowering water-lilies and the Giant Water Platter (Victoria cruziana) open their flowers at dusk, to provide a nocturnal display.
The most important consideration before planting and construction of the garden is the site. Full sunlight is essential for successful development of nearly all the aquatic plants. If the garden is shaded, growth becomes etiolated, and less floriferous. Trees growing in the near vicinity of a pool are undesirable as the leaves tend to accumulate in the pool, releasing harmful products as they decay under water. In wind-swept locations, a windbreak of the American Arborvitae or Canadian Hemlock planted at a suitable distance on the north side will prevent damage to the more tender plants, and also assist in extending the display season.
The source of water should be relatively free of salinity as well as industrial and municipal-wastes. Where fish are desired the water should be able to sustain a flora for the small organisms which serve as fish foods; and to have optimum dissolved oxygen content of 47%.
The design of the pool may vary from the formal or traditional with a rectangular or circular shape to the informal or more natural form. For the smaller gardens a simple pattern is advocated, being less complicated to build and maintain. This type is more likely to blend with the landscaping of a smaller garden. Eighteen to 24 in. is an ideal depth. To accommodate shallow water and certain moisture-loving plants, cement blocks or large stones can placed under the plant containers to bring them up to the correct depth of water (2-4 in.).
The best material for pool construction is concrete—preferably reinforced—poured into wooden forms. The site selected should be excavated to the necessary depth and outline. Provision for drainage should be made as this will facilitate periodic cleaning. The drain can be run to low ground or sump built nearby. Galvanized iron pipe 2-3 in. in dia. is excellent.
Puddled pools, with curved sides can be constructed. They may not possess: the permanence of a pool built with forms, but are less expensive and not so much trouble to build. They allow one to build a pool to almost any shape with a minimum of complications. After excavations are completed and provision made for drainage, the floor and sides are covered with a 3-4 in. layer of gravel or crushed stone which is then consolidated. Reinforced rod or mesh is then placed over this, layer. Six inches of concrete is then poured over the floor and sides, insuring that the reinforcing is raised evenly to work the concrete around it. The final smoothing can be carried out as the concrete commences to set. Burlap can be placed over the pool, and kept moist for a week or so in order to prevent the concrete from drying out too rapidly.
Freshly poured concrete will release a considerable amount of calcium, which subsequently causes the water in the pool to be too alkaline for both plants and fish. The pool can either be painted with one of the water-proofing com-pounds, or better still given an artificial “curing” or maturation treatment. This consists of several fillings and flushings—followed by a thorough scrubbing with a solution of vinegar—then drained and refilled for planting.
Prefabricated pools mainly of fiberglass com-position have become increasingly popular. They are obtainable in a wide variety of shapes and sizes, are extremely durable, and long lasting. All that is necessary is to excavate the depression to fit the pool, place in position, level and firm. Some of the more elaborate fiberglass pools are obtainable in 2 depths—to accommodate a variety of plant material. Heavy-duty polyethylene can also be used, its disadvantage being its limited length of life compared with the other types of pools. The excavated area is smoothed, all stones removed—then covered with a layer of sand. Then cover with a double thickness of the plastic film, allowing an over-lap of at least 6 in. on all sides. This can be covered with soil or better still with stones. Even the smallest garden can feature an aquatic display—wooden or metal tubs, half barrels, even kettles, can be used to provide a focal point of beauty, when planted with the smaller varieties of water plants.
A companion bog garden can enhance the pool, and provide a site to grow an extensive range of unusual plants such as the giant-leaved Gunnera manicata, bog primulas, certain native orchids and insectivorous plants, to name just a few. A bog garden does not have to be water-logged. All that is necessary is to allow the roots access to water at all times. Making an artificial bog garden is considerably less complicated than building the pool. The area selected adjacent to the pool is excavated to a depth of 12-15 in. The base can either be lined with heavy-duty polyethylene and lightly perforated or flat tiles. These are placed over-lap-ping to prevent too rapid drainage. The area is then filled with a mixture of 2 parts field soil, and 1 part coarse peat. An ideal arrangement is to provide a slow trickle of water from the pool to the bog, insuring a uniformly moist condition.
Many natural pools or ponds can be utilized to create water gardens. Some of the drawbacks include aquatic weeds which can offer severe competition; varying water levels; muskrats; and stagnation. A stream can be dammed and an area excavated to provide deeper, reasonably still water conditions. Spring-fed pools are often not practical for the tropical water-lilies, due to cool water temperature. Natural pools provide the gardener with maximum scope as regards landscaping the area around the pool, emphasis being to blend the pool with the surroundings, and to create as naturalistic an effect as possible.
In states where severe frosts occur, some form of winter protection for artificial pools is necessary. Logs or any floating object will take care of the effects of alternate freezing and thawing. For large pools expansion joints every 15 to 20 ft. will greatly reduce the danger of frost damage. Provided the crowns and roots of hardy water-lilies, lotus and other hardy plants are below the frost line, they will winter over satisfactorily.