While public gardens may build extensive concrete pools or use natural ponds to grow and display a wide array of aquatic plants, a water garden needn't be large and difficult or costly to maintain. Many design options exist to meet the aesthetics of gardeners--from informal, naturalistic ponds to more formal pools replete with blooming waterlilies.
Water Garden Design Style
Peter Robinson, author of "The Practical Rock and Water Garden" recommends creating a water garden that matches your personal perception of a water garden as well as one that matches the style of landscape. An informal garden will suit people who love a naturalistic look--curving water edges and lots of rock and plant materials. A formal garden comprises a geometric-shaped pool that balances or complements the lines and shapes surrounding a modern building. Informal designs lend themselves to including waterfalls and streams, whereas formal designs tend to display fountains particularly well.
The key feature to any water garden is the retention of water. Either a naturally low spot that retains spring or rainwater year-round is needed, or an impervious basin is needed to contain the water. Deep pools tend to contain cool water temperatures, as do those placed out of direct sunlight, especially in summer. Shallow pools typically warm up more quickly in the sun and can create a habitat that allows unattractive and unhealthy algae infestations. Mechanized pumps or filters can be used to keep water clean and visually clear as well as to facilitate moving waterfalls or fountains.
Water garden pools are constructed either from concrete or less expensive, temporary PVC liners or pre-formed resin/fiberglass basins. Match the construction material with your climate to ensure durability. Concrete ponds are long lasting but can be affected by freezing and thawing in winter. PVC liners and resin basins are flexible and lightweight and manufacturers tend to fabricate them with materials that resist weakening from the sun's UV rays. Liners and forms can be placed in the ground or used as a sleeve in a whiskey barrel, cracked (leaking) concrete pool, or other makeshift above-ground structure made of bricks, railroad ties or blocks.
Once water is in the pool, you can grow aquatic plants. These plants can either be grown floating on the water's surface, in soil at the edge of the pool, or planted into containers and submerged into the water. Common aquatic plants include water lettuce, water hyacinth, waterlilies, lotuses and cattails. Some plants grow better when the water is calm and not moving. Water that does not get too warm and plagued with algae or inhospitable chemicals will sustain fish life (goldfish, koi or minnows) as well as attract natural wildlife like toads, frogs and turtles.
For aesthetics, the edges of water garden pools are often lined with stone to help delineate the water's edge and to provide safe access to maintain the plants, animals or equipment. As a general rule, a pond should be at least 18 -inches deep to provide enough water volume to prevent water from warming too much the summer. This level may be deeper in cold climates to prevent ice from forming all the way to the pond's bottom. Ponds in shady areas under trees require cleaning and removal of decaying leaves, especially if fish are present. Chemicals can be used to treat water and prevent algae growth, but may cause harm to plants or animal life. Once established, the water garden becomes a self-sustaining small ecosystem.