Once you decide what kind of pond you want to install - pre-form or free-form - it's time to stake out the best spot for it in your backyard. Ideally, the location should receive both sun and shade during the day so that the frogs can choose where they would like to be. Once the location has been selected, mark the pond perimeter with a length of rope, string or garden hose, grab a shovel out of the tool shed, and start digging. If you chose a pre-formed plastic design, you'll know just what shape to cut and how deep to dig the hole. If you chose instead to be a bit more creative, the dimensions are entirely up to you. However, following a few simple rules at this stage of the project will save you a few headaches later on.
Once the hole is dug, leveled and lined with a soft material to prevent leaks, it's time to set the pre-formed pond in place (the top lip should sit evenly on the level ground) or to lay the plastic liner as smoothly as possible in the hole. There should be a half-foot or more of excess liner around the entire rim of the pond's edge, which can be trimmed later, if necessary. If you plan to decorate the pond bottom with sand, smooth pebbles or stones, this is the time to put them in. This is also a good time to position any mechanical pumps, filters or other water features you may want to add for water maintenance or effect.
You may want to use flagstone, slate and/or other flat rocks to form the border of the pond. They will sit on top of the excess liner and should be dug neatly into the surrounding turf. You'll want a border stable enough to walk on, but not one that juts out too far and might trap frogs in the pond. Small branches or logs placed at the edge can serve as ramps or bridges for frogs wanting to move back and forth from the water to the land.
Now it's time to fill the pond. Just lay a hose and run the water until it is within an inch or two of ground level. Since the water you'll be using is treated with chlorine and other chemicals, you'll want to let it sit for several days (perhaps as long as a week) to let these dissipate before adding any plants or animals.
There is a wide variety of aquatic plants from which to choose: submerged, emergent and floating species. Submerged plants remain underwater and tend to be feathery in their growth pattern. They remove carbon dioxide from and add oxygen to the water, helping to keep it pure and clean. Emergent plants grow from pots placed at the pond bottom of along the ledge, but grow above the surface. Water lilies, arrowhead, pickerel weed, cattails, and sedges are popular selections. Floating plants include duckweed, water lettuce and water hyacinths that rest entirely on the surface. They help to shade the water below and reduce algae growth, which can quickly turn crystal-clear water to pea soup green. If at least half of the pond's surface is covered by floating and emergent plants, good water quality should be maintained. If your pond does turn green, however, don't drain it and start over. It should eventually become balanced (the algae bloom will die off) and the water will clear.
You may wish to plant a variety of native plants around the pond, creating a natural landscape and adding to the attraction for other wildlife. This is also a good time to think about contacting the National Wildlife Federation and registering your property as Certified Wildlife Habitat (http://www.nwf.org/backyard/), since you are providing native amphibian populations with the essentials of food, water and shelter.
Dead leaves and other debris will ultimately accumulate on the bottom of the pond, not just from the plants you add, but from the surrounding shrubs and trees as well. This is not necessarily a bad thing, unless your yard is planted with species whose leaves are toxic. You may even want to purposely add some leaves to the bottom of the pond. Frogs like having someplace to hide when people or predators approach and there's nothing more natural for them than diving down to disappear under a layer decomposing leaves. In addition, your frogs may choose to hibernate on the bottom of the pond during the colder winter months if the leaf layer is thick enough.
At no time should you treat the area around your pond with toxic chemicals - herbicides or pesticides. These can find their way into the water. Amphibians have very sensitive, porous skins and can easily become ill or die if exposed to such chemicals.
If your pond attracts more mosquitoes than your frogs can eat, a circulating pump that keeps the water moving may help reduce mosquito numbers to more tolerable levels. You will want to attract some insects to the area as a source of food for your new frog neighbors. A simple way to do this is to install one or two low light sources around the pond. There are a number of inexpensive, solar-powered models available that will do the trick.
After the water has set for a few days and your landscaping chores are completed, it's time to add your frogs. Check with your state wildlife authorities to determine if native species can be collected or purchased to stock your pond. However, if you live in a rural area, there's a very good chance that frogs living nearby will just show up on their own one day and take up residence at your pond. Be patient. This may take several months, but wild amphibians seem very capable of finding water sources that offer a suitable places to live.
http://www.environment.gov.au/education/publications/frogpond.html
http://sagebug.com/howto/frog-pond.html
http://exoticpets.about.com/od/frogsandtoads/qt/frogsponds.htm
