Are some plants in your yard or garden crowding out (and even killing) other plants? You may have some green “invaders,” otherwise known as non-native invasive plants.
What are invasives? They are plants that aren't natural to your area—and were imported long ago for their beauty or for other reasons without the understanding that they lacked the local insects, predators, or diseases that would normally control their growth.
Invasive plants aren’t simply a plant problem. They also disrupt our natural habitat and animal wildlife. For example, fewer native milkweed would mean fewer Monarch butterflies. Honeybees and birds also look for native plants.
I have several “invaders” lingering on my property. Here is an aggressive vine that’s strangling—and, literally, killing—one of our trees.
Oriental Bittersweet (Celastrus orbiculatus) strangling a tree. Credit: USDA.gov
I also spotted these bamboo-like stalks that are taking over the area along my lakefront.
Japanese Knotwood (Fallopia japonica) is found among many shorelines and roads. Credit www.dcnr.state.pa.us
This past summer, I attended a talk by Louisa Birch from our local conservation commission; she specializes in invasive species. She taught me that the strangling vine was invasive Oriental bittersweet—native to Japan and China! I also learned that the bamboo-like plant is called Japanese knotwood—also native to Japan.
Both invasive plants are very difficult to manage—and we’re still learning the best techniques. For Louisa, cutting bittersweet doesn’t seem to work; herbicide is the only way to go. On the other hand, cutting Japanese knotwood seems to be the most effective way to slow it down; covering it with black plastic doesn’t have much effect.
Burning Bush (Euonymus alatus) is one of the most common invasives.
Ever seen the attractive burning bush? Yes, I had one of these beauties on our property. For years, we all imported these bright and attractive ornamentals from Asia. Now they are illegal because they outcompete and displace natives. However, there are wonderful alternatives to burning bush, such as the native shrub called Fothergilla 'Mount Airy' or Virginia sweetspire (Itea virginica).
Fothergilla 'Mount Airy' has vivid fall foliage similar to the Burning bush. Credit: www.botanicalgarden.ubc.ca
If you're in love with an invasive plant that is sitting on your property, there are many alternatives. For example, I can replace my invasive Oriental bittersweet with native American bittersweet (Celastrus scandens).
How to Control Invasive Plants
If you discover that you have invasive plants on your property, here are common methods of control:
• Cutting and mowing generally interrupts many plants’ ability to grow.
• For herbaceous plants with thin, woody stems (less than 1 inch in diameter), pulling and digging is often best.
• Certain plants require herbicides (best administered by a professional).
• A few plants respond best to biological controls. For example, the purple loosestrife (Lythrum salicaria) is eliminated with the help of Galerucella beetles (which you can have shipped to you via overnight courier)!
• When you do cut or pull out invasives, do not add them to compost piles; dispose of them in black plastic bags.
Stop the Spread of Invasive Plants!
What can you do? Here are a three simple ways that you can help:
1. Every state has a different list of problem plants. For example, in the South, did you know that beautiful wisteria is an invasive? Take time to learn which plants are invasive in your state at http://plants.usda.gov.
2. Get rid of the invaders! If you think that you might have invasive plants on your property, contact your local state cooperative extension office or garden center. (You could even get them a sample of your plant.)
3. Go native! Preserve our natural flora and fauna. Many local garden centers sell native plants. ” Or, just Google “native plants” and your location, and you can find out which plants really belong where you live.
I hope that you found this post informative. Please let me know what you think—especially if you’ve had experience with invasive plants.