Water garden installation requires forethought

By Sharon Omahen
University of Georgia

Before adding a water garden to your landscape, sit down and have a long talk with yourself.

"Ask yourself why you want a water garden," said Tony Johnson, a horticulturist with the University of Georgia College of Agricultural and Environmental Sciences. "Do you want goldfish or koi? Or do you just want a water garden with plants and no fish? Do you want to hear the water rushing?"

At the UGA Research and Education Garden in Griffin, Ga., Johnson maintains water gardens that are the envy of many gardeners.

Fish dine on mosquitoes

"I recommend adding a few fish to keep the mosquito larvae population down," Johnson said. "It's a misconception that water gardens bring in more mosquitos, because your water is moving and your fish are dining."

After answering the initial questions, select a site you can enjoy from outside and inside your home.

"Your site should be elevated to avoid runoff into your pond," Johnson said. "Runoff can introduce sediments, fertilizers and pesticides into your pond."

Don't put a water garden too close to trees. "If you build under trees, you'll have leaves in your pond," he said. "When they rot, they produce fertilizer that can turn your water green."

Next, determine the size pond you want and the type of liner. "Most people tend to buy preformed liners," Johnson said. "But I prefer to use the Permalon or EPDM rubber liners as they allow you to truly design the pond in the shape you want."

Don't cut corners

Above all, don't cut corners.

"Don't try to save money by buying roofing material or a swimming pool liner to use as a water garden liner," he said. "These materials can contain chemicals that can kill your fish. And a blue pool liner will reflect light, and light equals algae."

Use a garden hose to outline the pond's shape, then a shovel to cut out the design. Till the soil, then finish digging the pond.

"Most ponds can be dug by hand," Johnson said. "Just make sure you dig your pond at least 24 inches deep and that you leave a 1-foot shelf around the pond. This is where you'll set your potted plants."

For larger ponds, rent a backhoe.

Line the bottom with 2 inches of sand to protect the liner from underlying rocks. To see how much liner you need, measure the pond length, width and depth and add 1 to 2 feet.

"This will give you enough liner to lay in the hole and spread over the edges," Johnson said. "Don't try to skimp on liner. It's better to have some left over than not enough."

Camouflage sides with rocks

Anchor your pond liner with rocks. This secures the liner and serves as camouflage. Native rocks make the pond look natural, but Johnson doesn't recommend collecting them yourself.

"It's a lot easier to buy rocks than it is to collect them here and there," he said.

Many designers recommend covering the pond bottom with small rocks. Johnson disagrees. "I have a hybrid idea," he said. "I put small rocks around the edges, and they hold bacteria and create a biological filter."

Johnson said this method looks good and is easier, too. "I don't like all the rocks in my way when I get in the pond to clean the bottom," he said.

You may want to blend a pond into existing landscape by planting around the edges. "Select plants that hang over the edges and create a natural look," Johnson said.

Shop around for the best filter, pump

The final additions to your pond are the most important: a pump and a filter system. Johnson recommends visiting several pond suppliers before buying.

"This way you can see what's available in action," Johnson said. "When it comes to pumps, always buy a bigger pump than you think you need."

Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.