Water Gardens

Water gardens are becoming increasingly popular features of both commercial and home landscape design. A water garden in the landscape brings an immediate sense of tranquility and peace. Water gardens are fast becoming a favorite hobby for experienced and beginning gardeners. Water gardens can be as sophisticated as a series of waterfalls and pond levels, or as simple as a half wooden barrel filled with floating plants and small water lilies.

When considering installing a water garden, an important first step is to decide what you want from your water garden. Do you desire a place to have fish and grow aquatic plants, primarily water lilies; or, do you desire to attract wildlife such as frogs and toads to your yard? Perhaps you just want a peaceful area that will bring refreshing sights and sounds to your garden. Additionally, you will need to decide whether or not the water garden will be formal or informal. Formal water gardens have distinct geometric shapes and are usually faced with brick or cut stone to give a finished or sculptured look. Informal water gardens are more easily blended into the surrounding landscape and are usually free form in shape. As you prepare to design your water garden, there are three important factors to keep in mind: site selection, building material and plant selection.

Site selection is perhaps the most important part of the initial planning process. If you are planning to have aquatic plants and/or fish, there are crucial factors to be considered. A site away from trees is important to aid in keeping the pool free of leaves and twigs that will decay and eventually form excess organic matter that will have to be removed. Also, water lilies must have exposure to direct sun for a minimum of four to six hours per day to bloom well, but smaller water gardens need afternoon shade. A well-drained location is also important. It isn’t good to locate the pond in a low-lying area that will be inundated in wet weather. It is also a good idea to locate the water garden in a spot sheltered from the wind. If you have locations in your yard where debris collects easily after a storm, these sites should be avoided. And finally, it is advisable to locate your water garden so that water access is convenient. You may also consider access to electricity if you plan to run a water fountain or filtration system.

In years past, the only way to build a water garden was to make it

Water Lily

out of concrete or concrete blocks. These were not only costly; they tended to crack and leak as well. The most popular type of water garden installed today uses a synthetic liner to form the sides and bottom. These materials are lightweight, portable and adaptable to a variety of shapes and sizes. The most common type of liners are PVC-type which are durable for up to 10 years. As an alternative to flexible plastic liners, you can create a water garden using pre-molded fiberglass or plastic pools. These are more expensive than liners; however, they are easier to install since there is no molding and shaping as with plastic liners. It is important to keep plant depth requirements in mind when choosing liner types. Most pre-molded pools have only straight or curved sides which slope abruptly to the bottom, providing no shallow shelf for marginal plants that prefer not to be submerged.

Everyone would like pristine, clear water in their water garden; however, this goal is easier said than done. You may also want to add a filtration system (pump and filter) to achieve this goal. Biological filters involve circulating the water through porous substrate laden with beneficial microbes that remove nitrates, etc. from the water. Mechanical filters do this with screens and charcoal. Filtration systems are relatively inexpensive and are especially useful when algal growth is abundant. Algal growth can be a problem in the time period before the plants have grown to cover the surface of the pool. Once plants are established and cover 60 percent of the water surface, the threat of algal problems greatly lessens. At this point, many water gardeners opt not to use the filter system, but rather allow natural decomposition of debris materials on the bottom. Over time, a balance of recycling organic materials should occur, and if the proper number of plants and animals are present, filtration should not be a great concern.

The key to successful water gardens is to establish a balance of plants and wildlife. Too many fish and/or plants will cause the balance to shift so that nutrients are in disproportionate amounts, and the water garden can become overgrown with algae. Selecting the right type of plants is important in obtaining the proper balance. There are four categories of plants to consider planting: deep water plants, bog or marginal plants, oxygenators and floating plants. The most spectacular deep water plant is the water lily. Water lilies come in two types: tropical and hardy. Both types come in a

Water Garden

variety of colors from white to many shades of pink and red. They are easy to care for (especially the hardy types) and can be quite fragrant. Blooms float on or are held slightly above the water surface and may last for four to five days, closing every night and opening during the morning hours. Flowering can last for months. Bog or marginal plants grow at the edge of the pond in up to six inches of water. Plants in this category include cattail, iris, bamboo, rushes and tall grasses. They can be planted on a shallow shelf just below the waterline in containers and will transform an ordinary water garden into a more natural looking habitat. Marginal plants also provide protection for visiting animals and aquatic insects. Oxygenator plants play a key role in replenishing the oxygen supply. These plants remain submerged just below the surface and help prevent the water garden from becoming stagnant which aids in algal growth. These plants are quite winter hardy and include elodea, fanwort, hornwort and parrot’s feather. Finally, floating plants provide coverage for the water garden’s surface and thereby limit algal growth. These plants do not need soil and absorb nutrients directly from the water and are quite easy to grow. Included in this group are fairy moss, water hyacinth, frogbit, water lettuce and duckweed. Water gardening can be very rewarding, and hopefully the above steps will ensure you enjoy a beautiful water garden in years to come.

(Information for this article was gathered from the Missouri Botanical Garden Kemper Center for Home Gardening).

Mary Kroening, Missouri Master Gardener Coordinator and UMC Horticulturalist, (573) 882-9633