2017-05-20 / Outdoors


Avoid invasive ground covers

I’m continuing my series of columns on what to plant, and what not to plant, with a review of ground cover options. Unfortunately, as with invasive shrubs, there are ground cover options being marketed by some nurseries and other retailers that are very poor choices for northcentral Pennsylvania.

Some of them can easily spread into the wild, where they form carpets on the forest floor that prevent native wildflowers from growing. The majority are also unpalatable for deer and other wildlife.

They simply don’t belong here.

One of the worst of these plants is the ever-popular English ivy. It grows aggressively as a ground cover. Once established, it is difficult to eradicate. English ivy climbs up trees, eventually smothering them and killing them. Planting English ivy is playing with fire. Ecologically speaking, eventually it will burn you.

Periwinkle and creeping euonymus (also known as winter creeper) are similar in their appearance and growth habits as aggressive, invasive ground covers. However, periwinkle has the characteristic periwinkle colored flowers.

Both plants grow at ground level and have two-inch-long, oval-shaped evergreen leaves. They spread out from where they were planted through their roots. Roots also form where the plant stems touch the ground as they sprawl out.

Another invader, goutweed, is a popular ground cover for use around homes. It is usually sold as bishop’s weed. However, a variegated variety is sold under the name of “snow on the mountain.” Both forms rapidly spread through their rhizomes or roots, as well as by seed. The movement of soil, such as by construction activities, can transport goutweed to new sites.

Goutweed grows very well in heavy shade, forming a dense layer of vegetation that out-competes our native plants, especially woodland wildflowers. It is especially hard to get rid of, even with herbicides.

Populations of the nasty goutweed grow in large areas of the First Fork of the Sinnemahoning Creek corridor, upstream from Wharton, as well in the Quehanna Wild Area along Wykoff Run.

Japanese honeysuckle is another problematic plant. It has fragrant flowers and climbs up trees as a vine, but also sprawls along at ground level like a ground cover. It is tolerant of moderate shade and is very invasive. Be advised that native varieties of honeysuckle vines are available.

Two other dishonorable mentions for popular ground covers not to plant are pachysandra and moneywort, often sold as “creeping jenny” or “creeping charlie.”

Instead of these invasive ground covers, I recommend planting wintergreen, also known locally as teaberry, or partridge berry in moderate to semi-shaded sites. Besides the ground cover that these plants provide, their small fruits are edible.

In sunny areas, creeping flox is a good ground cover choice that is a beautiful, noninvasive alternative.

For areas of heavy shade, the best alternative might just be to mulch the area under the trees with bark mulch or wood chips. This will have the additional benefit of improving the microbial community in the soil to the benefit of the tree.

Please do your homework. Nurseries often use different names or a special cultivar name. A quick internet search of the plant’s name and the word “invasive” will bring up lots of information that will let you know if the plant has the potential to escape into the wild and cause ecological harm.

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