01 of 06
Invasive Ground Cover Thugs
Ground covers definitely have their place in the landscape, but they need room to roam. No border, no matter how deep, is going to keep them in check and mowing just makes them shorter; they do not disappear. Yet very often gardeners will plant a fast-spreading ground cover without really giving thought to what it will do in the future. They are looking for instant impact and fool themselves into thinking they will stay on top of keeping it in check.
Compounding the problem is the fact that these aggressive plants are still widely available for sale. While the following 7 plants are often sold in garden centers, they are true garden thugs. Left on their own, they will take over. If you don’t want to be ripping them out for years to come, resist planting them in the first place.
In some areas, plants like these go beyond aggressive and become invasive. Check the list of Introduced, Invasive, and Noxious Plants for your state, before you let one of these plants loose.
A word of warning: these plants are popular pass along plants. Your friends may mean well, but the reason they have extras to give away is that these plants are such rampant growers.Continue to 2 of 6 below.
02 of 06
Bishop's Weed, Goutweed (Aegopodium podagraria)
There’s no denying that the variegated form of Bishop’s Weed is an attractive plant. It even grows well in shady sites, where you need splotches of white to brighten things up. But you will never have just a little Bishop’s Weed. As it spreads, its roots from a dense mat, smothering out any nearby plants. That may sound nice for weed control, but it will eventually take over your garden plants, too.
Bishop’s weed was first listed as invasive way back in 1863, in Rhode Island, however, you will still see if for sale. One look at the white, umbel flowers, very much like Queen Anne’s Lace, and you can probably guess that it is a member of the carrot family. The flowers do attract beneficial insects, so the plant is not without its merits, but it is simply the wrong plant for many spaces. Check out the map on the Plant Conservation Alliance, Alien Plant Working Group’s website.
If you’ve already planted Bishop’s weed and regret it, your best chance of eradicating it is to exhaust it. Cut it down as short as possible in the early spring and then cover the area with plastic. The plants can't photosynthesize, they aren’t getting much water, and they are over-heated. It may take awhile, but eventually, they give up.
Bishop’s weed also goes by the name goutweed (a mishmash of goat weed - goats will eat it) or Snow on the Mountain.Continue to 3 of 6 below.
03 of 06
Bugleweed ( Ajuga species)
Bugleweed has pretty purple flowers and grows from ground-hugging rosettes. One individual plant looks harmless and charming, but it will spread by runners and quickly form a dense mat. There are places, like hillsides, where mat-forming plants are welcome. They prevent erosion and don’t need mowing or maintenance. But you should not plant bugleweed anywhere near your lawn or garden beds.
You can still find bugleweed in garden centers and it is still a very popular ground cover in some areas. There are some promising new varieties with dark purple leaves, like Ajuga "Atropurpurea", bronze leave varieties, like "Gaiety", and some edged with white, such as "Silver Beauty". Ajuga "Chocolate Chip" has gotten good reviews for being attractive, yet slow growing and fairly well behaved. But there are many other instances where the species makes itself too at home. The most common complaint is that it moves into the lawn and kills the grass. Although an attractive plant, you may not want an entire yard of it.Continue to 4 of 6 below.
04 of 06
Chameleon Plant (Houttuynia cordata)
It’s hard for a new gardener, and many experienced gardeners who should know better, to resist this plant. Although the flowers are hardly noticeable, it’s leaves are an eye-catching mix of red, cream, and green. While many gardeners who have succumbed to its charms, few would recommend it to others. Most are still trying to get it out of their gardens, decades after planting it.
The chameleon plant is a very rapid spreader. It’s fleshy rhizomes reach out and over anything in its path, forming a thick mat of roots that are impossible to thoroughly fish out and remove. Any remaining root will simply form a new plant and continue spreading. If you can smother it, as described above with bugleweed, or use one of the techniques discussed in this article on dealing with plant thugs, you should have success killing it eventually. But that’s not always possible when it’s become intermingled with other plants. Sometimes you have to sacrifice a few innocent plants, to finally rid the area of this thug.Continue to 5 of 6 below.
05 of 06
Evening primrose (Oenothera speciosa)
There are several very attractive flowers in the evening primrose genus. Sundrop (Oenothera biennis L.). has yellow flowers that only open during the day. There is also an attractive pink version (Oenothera speciosa) known commonly as showy evening primrose, Mexican primrose, or Showy Ladies, which blooms in the - you guessed it - evening. You don’t often see these for sale in garden centers, but they do still get passed along from gardener to gardener, especially the seeds.
Sundrops are biennial and Mexican evening primrose can be ephemeral, so you may think they have disappeared from your garden after flowering. Rest assured, the roots are not only alive and well, the plants have probably also dropped seed.
Evening primrose is not as hard to get rid of as some of the ground covers mentioned in this article, that spread by runners. However, because of its self-sowing habit, you will find clusters of evening primrose popping up throughout your garden and yard. Be vigilant.
By the way, evening primrose is no relation to the popular spring flowering primroses (Primula). These spread too, but not aggressively.Continue to 6 of 6 below.
06 of 06
English Ivy (Hedera hibernica and Hedera helix Baltica)
Ivy has been used so long as an ornament on venerable old buildings that it’s understandable that people would think it’s benign. While it has not been designated as invasive everywhere, it is still widely known to damage the buildings and trees it climbs on and clings to.
Where it is invasive, like in the Pacific Northwest, it will wipe out pretty much anything in its path, covering small trees, shrubs, and assorted vegetation, blocking sunlight and weakening them until it is the only thing left.
English ivy does not offer anything for wildlife or insects to munch on, so it will grow unchecked. If it escapes into the wild, it can potentially blanket entire forests. While the odd topiary or trailing vine in a container is fine, use caution if you need to dispose of plants at the end of the season. They will survive in your compost heap. The one place English ivy is safe is as a houseplant, in a container.
These are not the only troublesome ground covers, but they are some of the most popularly sold and grown. It’s easy to see why gardeners are still tempted to grow them, but we have enough headaches trying to stay ahead of weeds. We certainly don’t need to invite trouble into our gardens. In general, when you see the words “ground cover”, do some research before you welcome it into your garden.
Ground covers are not all bad news. Here are several you can even walk on.