RESEARCH GROUNDCOVERS BEFORE PLANTING
GARDEN TIPS – Written by Marianne Ophardt
WSU Extension Faculty
for the Tri-City Herald, Kennewick, WA Published September 11, 2016
Do your research first before planting any groundcover in your landscape. Too often a plant that seems to be perfect for the situation, becomes a nightmare or escapes and becomes a noxious weed in native areas. Here are two examples of plants that gardeners often introduce into their landscape and regret it later.
Snow-on-the-Mountain (Aegopodium podagraria): This plant’s other sobriquet, bishop’s weed, should be a clue that it can become a problem. Bishop’s weed, also known as goutweed, is a vigorous ground cover that thrives in shade and is very winter hardy. It is often planted by gardeners as a groundcover beneath trees where dense shade prevents lawn growth. Most gardeners prefer the variegated form of bishop’s weed, but there are also forms with solid green leaves. The plant also produces clusters of white flowers.
The problem is that bishop’s weed truly can become a weed in the yard and garden. It spreads by long branching rhizomes and also readily self seeds, making it difficult to contain within the area it was planted. Once established, it is aggressive and tenacious.
Bishop’s weed is an alien plant. It was supposedly introduced to North America as an ornamental plant by early settlers and was well established in the US by 1863. In some northeastern and mid-Atlantic states it has escaped cultivation and has become an invasive weed that reduces native species diversity. Research indicates that the main dispersal agent has been gardeners.
Heartleaf (Houttuynia cordata): The red-yellow variegated form of this plant is known as the chameleon or rainbow plant. Like the previous plant, heartleaf is a vigorous groundcover with a creeping habit. The leaves, variegated or solid bluish green, make the plant quite attractive. In early summer it produces pretty single white flowers above the leaves. Heartleaf is not drought tolerant, preferring moist conditions and full sun to light shade. It spreads by rhizomes, making it both invasive and doggedly persistent in the garden.
While this plant is quite attractive, it apparently has an odor when crushed or pulled. Fans say it has a delightful citrus or lemon-pepper aroma. Detractors say it is stinky and smells like a skunk or rotten fish. Comments like “Worst plant in the world. Do not plant it.” or “This plant is impossible to kill. It’s totally invasive.” from gardeners on various on-line gardening blogs, should make you think twice about planting it.
Heartleaf is native to Southeast Asia and Japan where it grows in moist, shady areas. It is grown in Asia as a vegetable and both the leaves and roots are harvested for eating. While I could not find that there is any concern about heartleaf becoming a noxious weed in the US, it is definitely considered obnoxious by many gardeners who have planted it.
I was able to find both of these plants on-line for sale from reputable nurseries and recommended as groundcovers by university experts. However, when considering what groundcover to plant, do a little research first. If descriptions indicate a plant is “aggressive,” “vigorous,” or “invasive,” I recommend avoiding it.
Are you interested in planting a groundcover that will not become a nightmare? Visit the Master Gardener Demonstration Garden behind the library at 1620 South Union Street in Kennewick. In parts of the garden you will find some groundcovers that do not become a problem after planting and are well suited to area conditions.