What are invasive plants? How do you keep invasive plants from spreading? Let’s dig in!
Have you ever stopped along a country roadside and dug up a flowering plant near the edge of a drainage ditch, thinking it would make a lovely addition to your garden? Or made a fall wreath from a climbing vine with gorgeous orange berries, then later tossed the wreath into the bushes out behind the garage?
Or maybe you’ve decided to let a piece of the lawn go wild to reduce mowing, or bought a piece of land that once pastured farm animals, but has gone “back to nature” because you keep no livestock.
That’s how I got purple loosestrife, a plague of Asian bittersweet, and acres of a thorny shrub called autumn olive. My “backyard” also sports impermeable hedges of Japanese knotweed (aka “bamboo”) plus multiflora roses and Japanese barberry. All of these plants are listed and regulated as “invasive species” in my home state of New Hampshire.
Once established, these non-native plants become challenging or even impossible to remove before they completely dominate a landscape.
What is an ‘invasive’* plant?
So-called “invasive” plant species generally refer to non-native (aka “alien”) plants that spread rapidly and threaten economic harm or the health of native ecosystems. Most states have enacted laws and regulations forbidding the sale, importation, or propagation of such species.
According to the Nature Conservancy, invasive species cost the U.S. economy $120 billion a year, with over 100 million acres (an area roughly the size of California) suffering from invasive plant infestations.
All plants have some geographical point of origin, an ecosystem where they co-evolved with numerous other plants, animals, and microorganisms over millennia, to the point where they keep one another’s populations in check.
To thrive, plants have evolved many ingenious ways to distribute themselves, among them
- Root systems that spread rapidly and invisibly underground.
- Seedpods that explode when ripe, spitting their seeds far and wide.
- Seeds so light they can float long distances on the wind.
- Seeds carried in the digestive systems of animals that eat their fruits and deposit the seeds some distance away in a little packet of scat that helps fertilize the ground they fall on.
- Seeds with barbs or burrs that stick to the fur of passing animals that transport them to new ground.
Humans took favorite plants with them as they traveled to explore, settle, and exploit new lands, a practice very much with us today. More recently, people have imported non-native species to introduce as ornamental specimens to gardens, to control erosion on disturbed construction sites, or for other purposes. Still other invasives hitched rides on ships transporting agricultural, forestry or other products.
In their new habitats, some (not all) non-native plants spread rapidly, since their new surroundings lack the plant diseases, predators, and strong competition from other plants that kept them under control in their native ecosystems.
Invasives include vines, grasses, herbaceous flowering plants, shrubs, and trees. Invasive vines may strangle native trees and shrubs; grasses, herbaceous species, and shrubs may crowd out native plants. They may reduce biodiversity by strangling or crowding out native species, degrade and destroy habitat, and destroy food webs by providing wildlife with less nutritious seeds or fruits than native plants.
Aquatic/wetland invasives are often spread between and among waterbodies by boats, trailers, and other recreational equipment. These plants may crowd out organisms within the ecosystem, clog waterways, kill or alter the balance of aquatic life.
How to stop the spread of invasive plants
If you’re a landowner, a gardener or farmer, a pond owner, a recreational boating enthusiast, or simply a citizen concerned about the health of your local environment, there are things you can do to help stop the spread of invasive plant species:
- Learn to recognize by sight the invasive species in your area and point them out to others.
- Don’t dig anything from the wild unless you’re certain it’s not invasive (or endangered).
- If you do see an invasive on you own property, dig it up, smother it, or follow instructions from your state’s invasive species program. Severe infestations may require herbicides.
- Plant native shrubs and flowers. They not only provide best food and shelter for native wildlife and protect the environment from spread of harmful weeds, but they are also easier to maintain.
Learn more about invasive plants
National Invasive Species Information Center (NISIC): Gateway to invasive species information; covering Federal, State, local, and international sources. To find information about invasive species in your state, type the name of your state into the Search NISIC box at the top left of the page.
*What’s in a name? Fascinating paper on how why scientists are searching for a new, more neutral framework for describing invasive plants.
Reader Comments
Leave a Comment
How to find help removing invasive trees and weeds
I am in Connecticut and now have awful invasive species plants and spreading mitten trees and it is all out of control -- cannot see what used to be pretty gardens. Lots of trees I want and I want to clean up the acre+ and keep it healthy. People say they do this stuff but they do not and get annoyed when I ask questions--my Dad, when alive, did all this caretaking and did share knowledge -- but I am treated like an idiot when I do not want to roundup kill every living thing on the property and replant my world. My Dad liked your magazine so I thought I might try asking you for help finding an honest company that can help me get this done this year. What do I do???
Weeds
The rental property where I live connects to city property and they are both textbook studies for noxious weeds! 100% of county's list. My issue is their way to control/ eradicate is chemicals! The city property is part of the rain water drainage flood plan and has it's own ecosystem, including but not limited to ducks, geese, and turtles. So I've learned to live with "weeds". Stickers, sandburs, thistle get a salt, vinegar, and soap treatment...at least I don't worry when I see a squirrel burying a peanut nearby. In my yard, as long as it's not stickery, it just gets mowed and even watered. It may not be the usual lawn but you can go barefoot and run your toes through it!
honeysuckle
We have it growing on a drainage pipe near our small creek bed. It is so hard to get rid of. Neighbors across the street let it grow through their hedges because they like it. I am sure that is how it spread here to our yard. Can't keep pulling this stuff, how do I get rid of it?
Honeysuckle invasive
Honeysuckle is very invasive and tough to eradicate. You need to cut them down to the stump and then spray the stump with herbicide two years in a row. Hope this helps.
Japanese Knotweed
Japanese Knotweed is NOT bamboo. It is even more invasive and almost impossible to eradicate. Look it up on Google. We "inherited" a huge swath of it when we moved to the country in Ontario. We spent the next 8 years trying to beat it back, with very little success. It sends out suckers that can be up to 15 meters long, and every part of it will reconstitute and grow more plants. It will grow through concrete paving, or anything else that is in its way. Don't EVER be tempted to buy it at a garden centre. In fact, if garden centres in your area are stocking it you should inform them that it is a noxious weed and they should get rid of it - and probably the only way will be by poisoning it.
Smothering under a tarp over
Smothering under a tarp over landscape fabric held down by heavy beams killed most of the creeping buttercup that was going to take over if I hadn't got to it soon enough. Left it covered a few months over the hot summer, now I am handpicking the pieces I see that I wasn't able to kill, it's a good thing to learn to recognize these invasives in advance since when I first saw it I left it to see what it would do/become.