You are at the nursery and have found a nice-looking plant. Is it safe to bring home? Your friend has some extra plants and offers to give you some – should you take them? In both cases, you can get into a lot of trouble by taking the plant home.
This is a list of invasive plants you should never, never, never add to your garden–unless you want them everywhere.
Nurseries should be restricted from selling them to unsuspecting customers.
See also Products You Should Not Buy!
What is an Invasive Plant?
An invasive plant has two common characteristics. It spreads fairly quickly either by seeds or a running root system. Secondly, the root system is nearly impossible to remove. Any small bit of root left in the soil will grow again.
This is by no means an exhaustive list, but it does contain some of the worst of the worst. I have struggled with almost all of them.
As one of the commenters below points out, invasiveness is regional. Something that may be invasive in zone 5 may not grow in zone 8, for all kinds of environmental reasons. This list of plants is invasive in zone 5, Ontario, in clay-type soil, and probably most of Northeastern North America.
Goutweed (Aegopodium podagraria)
Lily-of-the-Valley (Convallaria majalis)
Chameleon Plant (Houttuynia cordata)
Ribbon Grass (Phalaris arundinacea)
Periwinkle (Vinca minor)
Mint (Mentha species)
Sedum acre
Lyme Grass (Leymus arenarius)
Running Bamboo
Bell Flower (Campanula punctata)
References:
1) Goutweed (Aegopodium podagraria) Photo: Funki Sock Munki
2) Lily-of-the-Valley (Convallaria majalis) Photo: yamaken
3) Chameleon Plant (Houttuynia cordata) Photo: Sunchild57 Photography.
4) Ribbon Grass (Phalaris arundinacea) Photo: Learn to Grow
5) Periwinkle (Vinca minor) Photo: Patrick Standish
6) Mint (Mentha species) Photo:
7) Sedum acre Photo: Sólveig Zophoníasdóttir
8) Lyme Grass (Leymus arenarius)Photo: Thompson & Morgan
9) Running Bamboo Photo: Heather Bailey
10) Bell Flower (Campanula punctata) Photo: Qwen Wan
Florida betony is spreading rapidly for me even though I pull it up by hand and spray with roundup (maybe not strong enough a dose–I use 6oz to a gallon of water).
Follow instructions on the label. Roundup is available in many formulations and dilutions. It also takes 10 days to kill something.
I have noticed RoundUp hastens flower and seed production in poison parsnip. The last thing I want in my meadows. Now I just use a shovel and a garbage bag when they start to flower for easier spotting.
While Campanula puncata is a definite thug that I would never plant, people should be aware that there are lots of beautiful Campanula species that are definitely garden worthy. I currently grow 6 different types and all are well behaved.
Depending on its location, spotted dead nettle (Lamium maculatum) can easily become invasive. As can yellow archangel (Lamium galeobdolon). I learned that the hard way 🙂
I have a patch of polygonatum (Solomon’s Seal) which has taken over an entire flowerbed, totally choking out the columbines and Bleeding Hearts that were there. Every year, rhizomes make their way under the edging and wind up in the lawn, where I yank them out. It’s coming up on a vigorous patch of bletilla striata now. It’ll be interesting to see which wins. I love the polygonatum–and hate it. In a prepared flowerbed it is a nightmare. On the edges of woods where nothing else is growing, it’s tough, durable, and attractive.
All plants compete for space, and the stronger ones survive. It is quite common to have plants that need to be corralled by gardeners.
You either need to keep on top of them, or move them to a less hospitable location. They can be quite dry, and then they don’t spread as much.
I’ve been killing a patch of mint all summer that I started 7 years ago. Still haven’t got it all.
If I want mint for Mojitos, I’ll grow it in a pot.
Why are we so neurotic about beautiful plants. I wish I could grow the beautiful Lily of the Valley in my hot climate. Mint is a useful herb
herb and can be easily contained!
I had some lily of the valley and got rid of the clump. I am now finding clumps in my woods that can only be there through seeds. I know of several native places that are now fully covered with this weed.
Thought I would try some mint too – that was 5 years ago, and only left it in the ground for 1/2 the summer. I have worked hard at ridding it, but it is still showing up in my iris even though I pull every piece I see.
Hahaha! I tried growing mint in my perennial veggie garden in a sunken 17” nursery pot with 2” sticking up. Darn thing climbed over and rooted into the soil outside argh!
I totally agree with you. I wish I had all these beautiful plants these people are killing off.
A great way to get rid of Houttuynia once it has started growing into other plants is to take a 1 gallon black plastic pot and cut the bottom out. You can use this to encircle the stems of the Houttuynia and then spray with RoundUp without harming nearby plants. I credit my buddy Mary for coming up with this solution.
Katie in Illinois
I use a kids beech pail, and a paint brush – I can apply roundup very strategically.
Do you think that would work for quack grass which is my main issue here in eastern Ontario? Will it kill all the way to the attached grasses?
What is “that”?
Elymus repens also known as couch grass. Long pointy dagger like roots that go for miles under and through everything.
I am in the process of trying to get rid of the Chameleon plant by digging it up, but some places I can’t get to. How did you get rid of your plants?
Thanks
I painted the leaves with Roundup, and even with this it took several years before they were gone.
I think whether something is “invasive” or not is dependent on local conditions. Along Colorado’s front range, yarrow can take over in short order and myrtle spurge (Euphorbia myrsinites) is listed as “Noxious” by many counties. But vinca doesn’t do very well out here; it will sometimes make a passable shade ground cover, but I don’t see it get out of control and municipalities don’t list it as a problem.
You are absolutely right. I was in Colorado 2 years ago and got a chuckle out of the signs saying myrtle spurge (Euphorbia myrsinites) was invasive. Here it does spread a bit, but I’d hardly call it invasive. I have never seen it outside a garden.
#11 – Scilla sibirica – a welcome sea of blue in March turns into a horrible mess of prostrate leaves which hang on for 2 months. Never let them go to seed in a perennial garden!