Do you have a spot in your yard which you despair of because it is poorly-drained and consistently moist? Why not consider turning a liability into an asset by creating an intentional wetland?
There are several types of wetlands, such as bogs, marshes, swamps and fens. Each wetland hosts a different ecosystem with unique characteristics:
A bog tends to be waterlogged soil without any standing water (and therefore not a mosquito magnet).
A QUAKING BOG is a floating mat of thickly woven mosses, rushes, and shrubs that forms across the surface of shallow ponds and may shimmy or shake when walked on.
A fen is an area of waterlogged soil that tends to be peaty and is fed by upwelling water. The difference between a bog and a fen is the water source and the acidity of the site. Bogs tend to be acidic; fens are more alkaline. Water flows into bogs solely through rainwater and run-off, while fens are also fed by groundwater.
A marsh has standing water – either temporary or permanent – and hosts vegetation such as cattails.
A swamp is a wetland area with trees.
Wetlands are one of the richest biological habitats on Earth. Unfortunately, for centuries we humans have viewed them as a physical constraint and have drained them for use by the ever-growing population. The eradication of wetlands is a global phenomenon, primarily for agriculture. In addition, people mine bogs for peat for fuel and a soil conditioner.
Recently, environmentalists recognize bogs for their role in regulating the global climate. Bogs are unique communities that can be destroyed in a matter of days, but require hundreds of years to form naturally.
A strange mix of plants thrive in the bog. Cranberries and blueberries from the arctic tundra grow next to orchids and insect-eating plants from the tropical rain forest. Carnivorous plants obtain nitrogen from insects that they can't get from the nutrient-poor bog.
Building a Bog Garden
Important: Please note that I'm discussing two different soil types in this article. First you need to decide whether you want an acidic bog (more specialized, more TLC needed) or a bog containing regular topsoil. Because it requires so much diligent attention, an acidic bog is not for everyone.
Choose a level sunny spot that gets five or more hours of full sun.
Because shallow excavations dry out quickly, a bog garden should at least 1-1/2 to 2 feet deep to accommodate the root systems of mature plants.
After excavating, line the hole with a sheet of pond liner. Use a single, unbroken sheet because overlapping sheets will leak. Press it into the contours of the hole. It is wise to leave about 12 inches of liner exposed in case the bog settles further; this edge can be hidden with mulch, pine needles, rocks, etc.
For the non-acidic bog, some drainage is necessary to keep the crowns of the plants (the point where the roots meet the top growth) from rotting. To prevent this, poke drainage holes around the periphery of the liner, a foot below the soil surface.
Then fill the hole with a mixture of coarse sand and peat moss for an acidic bog, or with topsoil for non-acidic. The trickiest part of this process is thoroughly wetting the peat moss. Choose a hot day, take off your shoes and socks and stomp a la "I Love Lucy" grape stomping. Better yet, invite a few crazy friends to a Peat Stompin' Party.
Let the bog settle for a week or so before planting. The pH of the sand and sphagnum mix and the water need to come into balance before the plants are added.
In nature, a bog contains plants that are uniquely adapted to wet, acidic soils–acidic because little or no water flows through the bog and so no acids are leached away. In an artificial bog, you can either grow these specialized plants or a wide variety of perennials, bulbs and shrubs which require constantly moist non-acidic soils, such as bog rosemary, turtlehead and blue flag iris. When buying plants, make sure you choose the correct type for the type of bog you've chosen. Before planting, wash all the soil from the roots of the new plants to avoid introducing soil-borne microorganisms and worms.
Plants for acidic bogs
There are many colorful varieties of Pitcher Plants (Sarracenia) which can live up to 50 years, hardy Sundews (Drosera), and Venus Flytrap (Dionaea).
For non-acidic bogs: Astilbe, Bamboo, Lady's Slipper Orchid, Day Lily, Siberian Iris, Creeping jenny, Rush, Royal Fern, Phlox, May apple, Solomon's Seal, Primrose, Great Bulrush, Golden Rod, Periwinkle, Trillium. Here is a helpful website:
The most important maintenance job for an artificial bog garden is watering. Never let the soil dry out. Dry soil means sure death for moisture-loving plants. As with any garden, remove weed seedlings before they become a problem. In the winter cover the garden with several inches of mulch to help protect delicate plants.
Use only rainwater or distilled water in the acidic bog. Tapwater contains minerals and chlorine harmful to bog plants. It is also neutral to alkaline in pH, and bog plants need a highly acidic soil. Acidic bogs are naturally low in nutrients, so do not add fertilizer.
Other Ways to Build a Bog
If you don't have room for an in-ground bog, you can still have a bog garden. Try using an old whiskey barrel or other container that holds water. You can use kids' wading pools, utility sinks and even old bathtubs to make bog gardens. Your imagination is the limit. With a little ingenuity, anyone can have an artificial bog garden.
I'd like to thank a former student, Andrew Geis, Bogmaker Extraordinaire, for his counsel on this article.
The Idea Garden on the west edge of the hospital grounds now has a brand-new bog!
You can view it while you are taking in the Open Air Seminar on Saturday, July 21 at 9 am. It will be about drought-resistant plants and summer garden care.