If you've been struggling to landscape a low-lying soggy area of your yard, a bog garden might be just the perfect solution. A bog garden is low-maintenance and there is an astonishing variety of beautiful plants that don't mind getting their feet wet.
"A bog garden needs to be a wet, swampy area with about eight to 10 inches of water," says Dennis Trost, owner of In Thee Garden, a division of Southern Oregon Nursery in Medford. It can be created either by digging a hole in the ground or by using a plastic liner. An irregular shape will look more natural than a square or rectangle. The secret is to keep your hole shallow or it will become a pond. If you're lucky enough to already have a poorly draining low spot in your yard, you can just start happily planting away.
You can have a bog garden with or without a pond, but a bog can serve as a natural filtration system for your pond, according to Dennis Trost, owner of In Thee Garden at Southern Oregon Nursery in Medford. Ponds can accumulate toxic levels of ammonia and phosphates resulting from leftover fish food and waste. An "unbalanced" pond can become a green murky mess of algae and bacteria. He suggests incorporating a bog garden into about one third of the surface area of your pond.
The right bog plants will "out-compete" algae for nutrients, resulting in clearer water in your pond. Large leaves of plants such as water lilies shade the water, preventing the growth of sun-loving algae, and plants like Canadian pondweed (Elodea canadensis var. gigantean) trap particulate matter in their leaves, stealing the algae's food. Finally, scavengers available at water garden suppliers, such as certain types of snails and tadpoles, eat algae and leftover fish food, further helping to keep the pond clean.
There are plenty of moisture-loving plants for both sunny and shady locations, according to Trost, although a shady area will be easier to keep moist if your bog is man-made. Sun lovers include iris, sweet flag, horsetail, carex, arrowhead and some daylilies. Louisiana irises are some of his most popular sellers, because they come in pinks, blues, violets, reds, white, variegated purple and varying shades of all. Japanese and Siberian iris are generally blue and yellow.
Blazing spikes of purple, red, and lavender on Lobelia cardinalis attract hummingbirds and butterflies to your bog garden. Airy plumes of white and pink meadowsweet and astilbe brighten up shady areas. Other shade lovers include dwarf horsetail, red-stem sagittaria, and lizard tail. "Canna lilies are popular both for their big foliage and colorful blooms," says Trost.
Bog lilies are the number one favorite of Will Danielson, owner of Advanced Landscape Design & Maintenance in Jacksonville. He says they are "fairly easy to grow, don't take a lot of maintenance, and come in lots of colors," including a new 2007 red bog lily with gorgeous burgundy foliage and large pink flowers. A fun addition to your bog garden could be carnivorous plants. Venus flytrap or sun dews (Drosera) trap and eat flies and other bugs attracted to their open flowers and nectar. You can even grow your own cranberries, although Danielson warns they can be invasive and will need to be severely cut back.
Trost adds you should ask about other invasive plants, such as parrot's feather, cattail, chameleon plant, goldrush weed and some yellow iris.
All of these plants do well in this area and have few special needs besides cutting back and separating of the lilies, according to Danielson. He says if your bog is in an open area and it's an especially cold winter, some plants may freeze. Trees help provide protection. Bogs occur normally on north slopes with morning sun, but no hot afternoon sun, so he suggests putting a sprinkler on your bog in times of extreme heat. In addition, you may have to remove some of your tropical additions to a warmer winter home. Check the plant's hardiness before you buy.
Because a bog doesn't have standing water and is shaded by its plants, mosquitoes and algae aren't usually problems, says Trost. If you do get some mosquitoes, a natural product called Mosquito Dunks will kill larvae in standing water. Fertilizer stakes will nourish your bog for the entire growing season.
So you have a choice: hire expensive grading equipment, install drains or bring in loads of dirt to your soggy area, or fill it with beautiful flowers and foliage. Your moist oasis will be a welcome retreat when temperatures reach triple digits.