How Bog Gardens Work

Dig In: Excavating and Choosing a Pond Liner

Bog gardens work best in sunny, low-lying spots. A difficult, soggy area in your yard where water collects is ready-made for bog gardening. The bottom of a slope or an area near your house where the bog could catch runoff from the roof would also work well. Bogs are often cultivated along one or more sides of a pond to create soft edges that transition naturally into the landscape. You wouldn't want to put a bog on a hillside or in full shade.

Bog gardens require quite a bit of work at the outset. The first step is to dig out a trench with a flat bottom and slightly sloping sides, setting aside the excavated soil on a tarp. The bigger and deeper the hole, the less maintenance the bog garden will require -- at least in terms of watering. A depth of 18 to 30 inches (45.7 to 76.2 centimeters) ought to do the trick [source: Burrell]. If you happen to have a pond, give it soft, natural looking edges by connecting either an independent or an attached bog garden [source: Fisher].

  • To make an independent bog garden, leave a dam of hard-packed soil higher than water level along one edge between the bog and the pond. This prevents water in the pond from seeping into the bog and vice versa.
  • Create an attached bog garden that waters itself by taking moisture from a pond. Leave a hard-packed dam a little lower than the pond's water level, and top it with a semi-permeable substance such as sod or stone.

By far the cheapest and easiest way to line a bog garden is with an artificial membrane. Just calculate the size you need, lay it evenly inside the trench and hide the edges under rocks or cascading ground cover. You could also use a hard shell liner or even a plastic pool. If you hit clay during the excavation process and don't mind a lot of extra work, you can remove some of it and use it to create a watertight basin for your bog garden. Mix the clay with a little water until it is malleable, and then smooth it over the bottom and sides of your trench, using a rammer or a heavy tamping tool to pack it down [source: Perry]. You could also use concrete to line your bog garden; however, if you go this route, consult with your local garden center, since some sources suggest blending the cement mixture with other substances such as sand or washed shingles.

Now that you've seen what sort of vessel it takes to house an in-ground bog garden, let's fill it with soil and talk about how to keep it watered.