Water Gardens

Water is used in the landscape to create areas of calm and restfulness (though that certainly hasn't been the case throughout the midwest this year). Water features are not difficult to incorporate as long as important considerations are kept in mind. Two basic styles of water gardens exist, formal and informal. Formal pools have symmetric or geometric shapes and are appropriately used with neatly pruned shrubs and trees, in the middle of a large expanse of lawn, or as a focal point of a garden. The effect created is that of order and clear planning. Informal pools consist of irregular shapes which are more often associated with nature. The pool border blends into the surrounding landscape without clear definition. This type looks completely at home in the country or city. The pool form chosen should work with the style of your home and existing gardens.


Once the particular style of water garden is chosen, selecting the appropriate size is next. Keep the size of pool in scale with the setting to complement the area. The types of plants desired will also help determine size. Site requirements include placing the pool in a location where runoff from the surrounding landscape will not occur. Although it looks most natural to place the garden in a low-lying area, surface water will need to be diverted so it runs around the pool instead of into it. Soil under the pool should be well-drained to prevent heaving and possible flooding of the pool. In many situations, it will be necessary to line the area with several inches of sand to level it out and prevent injury to the liner. Sunlight requirements vary with the type of plants selected. For most water lilies, a minimum of 6 hours of sunlight is needed for flower production. More shade is tolerated by other aquatics; however, it is best to choose a site away from overhanging trees. Decaying leaves can rob plants and fish of oxygen as well as clogging pumps and filters. Locate the pool where it can be enjoyed to the fullest. It should also be located near electrical and water sources for convenience in pump operation and filling of the pool. Water ponds, even though quite shallow, can be dangerous for young children. In this situation, a tub garden may be a better alternative. Before beginning installation of the garden, check local zoning ordinances for any regulations. In many cases, pools deeper than 18 inches will require a fence or wall.


Pool installation can be done yourself or by landscape contractors. Prefabricated pools are available in a wide variety of shapes and sizes. Many are made of rigid fiberglass and are very durable. Discoloration occurs when exposed to air and sunlight, but life of material is not shortened. Less expensive and less durable pools constructed of bonded resin and semirigid or ABS plastic are also available. Flexible PVC sheeting materials, 20-mil single-ply, 32-mil double-ply, or 30-mil double-ply are good choices for lined pools. The main drawback of PVC is it deteriorates when continuously exposed to ultraviolet light (sunlight). However, well filled pools should last a minimum of ten years. Pool depth varies with size. A pool should not be less than 15 inches deep, eighteen inches is preferred. A pool with 40- square feet of surface area should be 18 to 24 inches deep. Pools with between 100 and 200 square feet of surface area should be at least 24 inches deep.

Water treatment

Pools can be filled with tap water from the garden hose. Chemical treatment of the water can harm plants and fish. Ordinary chlorine won't harm plants, however, chlorine compounds may. Check with your local water authority to find out the chlorine form used. If ordinary chlorine was used, allow the water to stand for 24 to 48 hours before introducing fish. Chlorine evaporates readily. If chloramine or chlorine dioxide are used for water treatment, materials can be purchased from fish and water gardening suppliers to counteract these chemicals.

Plants to Include

  • Flowers for water gardens include:
    • water lilies
    • lotus
  • Bog plants include:
    • arrowhead
    • cattail
    • horsetail
    • iris
    • marsh marigold
    • sweet flag
    • and several others can be used
  • Submerged plants, also called oxygenating plants, have their foliage under the water surface. Some to choose from include:
    • anacharis
    • dwarf sagittaria
    • vallisneria
    • water milfoil
  • Floating plants have their root systems hanging into the water with their leaves and blossoms on the surface. Floating plants to choose from include:
    • shellflower
    • water hyacinth
    • water poppy

When selecting plants for your garden, consider the mix of plants. No more than 70 percent of the water surface should be covered with leaves of aquatic plants. Select miniature varieties to allow for greater plant selection. Many water plants are winter hardy for our area making maintenance much easier. Others need to be removed from the pool prior to the onset of cool weather to ensure survival.

Even in this year of excess moisture, water gardens are enjoyed by many gardeners.

This article originally appeared in the July 21, 1993 issue, pp. 1993 issue, pp. 120-121.


Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Yard and Garden, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on July 21, 1993. The information contained within may not be the most current and accurate depending on when it is accessed.