New gardeners beware! One of the worst rookie mistakes we can make is to introduce invasive plants into our gardens. I ignored a lot of good advice when I started out, but honestly, no one warned me about these plants. With the emphasis on the benefits of local growing and shopping, I think we’re a little more savvy now. Or I hope so.
If you only study one thing before you start, find a reliable source in your area that lists known invasive and banned plants. You cannot rely on garden nurseries or neighbours to advise you on these things: sometimes they don’t know or don’t care. But believe me, if you end up with something in your garden that takes over your growing space, you will regret it forevermore. Some aggressive plants are just impossible to get rid of.
Invasives vary by region: what’s native in one area, does not have the checks and balances of it’s natural eco-system in another area. I’ll show you my plant regrets at my old zone 5 (Ontario) garden so you can get an idea of how serious this can be. Read my tales of woe and take heed!
The Invasives I Unknowingly Introduced
Mint (peppermint) – This was the first free plant that I was given by another gardener when I was just getting started. In hindsight, it’s not a gift at all but a test I failed by simply ever planting it. That one mint plant became a swath of relentless growth, spreading by roots, undaunted by even the hardest clay soil. Today I still grow mint but only pots where I can contain it.
Lemon balm – I love the smell, especially when the lawn mower catches it and the air fills with that sweet lemon scent, but this eager grower also took over a huge area of my old garden and no amount of pulling, digging, or smothering could get rid of it. Today, if I want to smell lemon, I’ll get a lemon.
Obedient Plant-Design wise, I love this plant. It’s one good looking plant. Like a rigid, compact foxglove with good posture. But wow, once this plant started spreading, it was choking out my Asiatic lilies and everything else it could get near. One summer I thought I had pulled it all out, and more plants returned. I swear I could hear the roots creeping through the soil as I slept.
Donkey Tails (Euphorbia): In some zones they are considered horridly invasive. In my garden, they became insanely dominant because I wasn’t careful to lop their heads off before they’d go to seed and spread by wind to the neighbor’s garden. I liked them for a while but everything loses its appeal when it grows too easily. Gardening is like a great game: there has to be that perfect level of challenge to remain engaged.
Musk/prairie mallow I had the kind that is a most annoying pinky/light purple colour. It’s not pretty and it self-seeds everywhere. Enough already! And to make matters worse, it’s easy to mistaken for hollyhocks when it’s just sprouting up so often you don’t know to pull it out until it’s rather tall. The hollyhocks are welcome, the mallow: not!
Goutweed. There are no words for how frustrating it is. I think you’d have to excavate all of its soil with a Bobcat digger to begin to get rid of it. And then nuke it. Twice. Of all the invasives, this one is my worst nightmare.
Garlic mustard – Some years ago garlic mustard suddenly had a stellar growing season. It was EVERYWHERE. In every garden, every walkway, every lawn, along the paths in the woods. Evidently, growing conditions were perfect and it just flourished. I spent hours and hours pulling volunteer mustard seedlings out of my garden. After about 3 years, it was no longer a problem.
Each year’s growing conditions favour some plants and make others struggles but the Year Of The Garlic Mustard was the most epic one I can recall.
A Short-term Solution That Creates More Work In The Long Run
It sounded too good to be true, and for me, it was. One year I set down a lot of landscape fabric under my garden rocks. And it did keep the weeds down for about a year. And then I realized the weeds were simply forming monster roots under the fabric and when they finally did poke through, they came up with a vengeance: all tangled up in the fabric no less, so everything had to be yanked out which was far more work than simply weeding. When it comes to weeds, there is no free lunch.
Double digging is often recommended in garden books and magazines as a means for dealing with clay soil. In my experience, it’s a complete waste of time and energy. I couldn’t begin to make my clay garden flourish until I added many inches of good compost and loose (not clay) soil on top of the hard clay. All the double digging ever achieved was to temporarily break the clay apart. Time and rain would cause it to meld back together again. It did, however, end up providing a good base for better soil on top.
Feel free to add your problem plants in the comments.