Invasive plants aren’t always what we think.
This is creeping bellflower. It’s cute, it’s a pretty purple, the bees love it.
And I hate it.
I noticed this slim, delicate flower the first summer after I moved into my house. I thought, I’ll leave this alone and see what it turns into. Big mistake.
Six years later, it’s still trying to take over my yard.
A weed by any other name
The thing is, creeping bellflower (Campanula rapunculoides) isn’t technically a “weed.” It was a garden flower brought from Europe (like dandelions) and planted intentionally by well-meaning gardeners years ago. It’s tenacious, spreading through both underground rhizomes and by producing massive amounts of seeds, as many as 15,000 seeds per plant. But this super-aggressive plant from another place doesn’t have natural enemies here to keep it in check, like a particular disease or insect or other equally aggressive plants.
As a result, creeping bellflower has moved in and is trying very hard to take over, kind of like that annoying sort-of friend who asks if he can crash on your couch for a few days, then proceeds to eat all your Doritos and mess up your Netflix algorithm by watching non-stop bad science fiction movies. A month later, you’re wondering if this guy has any intentions of leaving.
In the case of creeping bellflower, the answer is “no.”
The difference between invasive plants and regular weeds.
It might not be obvious why something like creeping bellflower would be a problem. It’s green, the bees like it—what’s the big deal? Here are a few reasons.
They crowd out the native plants.
In the plant world, it’s all about numbers. The plant with the most seeds, the fastest-spreading roots, the fewest predators wins. Most native plants are pretty tough and can hold their own once they’re established and have formed a decent patch. But a plant like creeping bellflower crowds in, hogging the nutrients, the water, and if it’s a tall plant, the sunlight.
They don’t provide the nutrition to pollinators that native plants do.
Native plants and native pollinators go together and are mutually beneficial because they have grown up together, so to speak. That’s why butterflies and moths have host plants: These are the plants they are tuned into, and the only plants their larvae can eat. If an invasive crowds their host plant out, either unintentionally like creeping bellflower, or intentionally, like a massive milkweed-free lawn and a garden full of non-native plants, the local pollinators and their larvae have nothing to eat.
But imagine this on a larger scale. It’s one thing to have creeping bellflower invading your yard. It’s another to have buckthorn trees invading entire forests, making them inhospitable for native trees and the creatures that live in them.
How to get rid of invasive plants.
A plant becomes an invasive when it gets away and becomes hard to eradicate. Creeping bellflower’s double threat of aggressive rhizomes and massive amounts of seeds makes it hard to get to it before it takes over. The Minnesota Department of Natural Resources provides a list of plants they consider invasive because of the threat they pose to the native ecosystem and methods for getting rid of them.
The best practices are, like with any weed, get to it early and often. A herbicide like glyphosate would probably take care of it, but I don’t want to use that and with the bellflower tucked in amongst all the plants I do want, I wouldn’t be able to use a glyphosate spray without damaging the plants I want to keep.
So all I can do is stay vigilant, pulling up the plants before they have a chance to flower. And where I can, I’ll try to dig them out by the roots, too.
Dispose of properly.
With plants like this, just like with weeds or diseased plants you’ve pulled up, don’t dispose of them in your compost pile if you intend to use the compost later on your garden! You can’t guarantee that the pile will get hot enough to kill the seeds or the roots. Then, when you spread the composted dirt out on your garden later, you’ll just spread everything, seeds and all, right back into your garden. If your city maintains a municipal compost pile where you can dispose of yard waste and it’s properly maintained, you could dispose of plants there, but the best thing to do is to bag up these plants in paper bags and put them in the garbage.
Don’t contribute to the problem.
When you’re researching your plants before you buy them—especially if any of them are non-natives—read up on them in a couple different reliable sources. Not just some schmuck’s gardening blog. Along with the other things you’re checking on, like soil and light preferences, notice if the description says anything about it being overly aggressive or a garden bully. Check using its Latin name, so you can be sure you’re reading about the same plant.
If you still want that particular plant in your garden, think about how you will control its spread. One way to control a plant that spreads underground by roots or rhizomes is to plant your plant in the ground in a container. Take a lightweight plastic plant container, the kind that many plants come in, cut out the bottom, then put the plant back in and plant it in the ground, container and all, keeping the top edge of the container even with or just above ground level. The container prevents the roots or rhizomes from spreading horizontally. I did this with my ribbon grass, which spreads through its roots right at the surface.
If it spreads through seeds, plan to deadhead a lot. Stiff goldenrod (Solidago rigida) is a great native plant that provides food to a lot of native insects, but it reseeds like crazy. That’s fine out on the prairie, where there’s lots of room and life is tough, but that’s too agressive for my little yard. I want some goldenrod, because it’s such a good plant for pollinators, but I’m going to look for another variety that doesn’t spread as fast and hard. If I can’t find one and I do plant Solidago rigida, I’ll have to be sure to be out there pulling off the dead flowers before they set their seeds. That’s too bad, because the seeds are good for birds, too, but it’s a give and take, and this is what many gardeners don’t understand when they bring in plants just because they’re pretty or they’re the latest thing: that plant may not want to stay obediently in its place. If I want a certain plant, I need to do some homework on it first, and if I find out that it’s aggressive, it’s my responsibility to keep it in check.
Aggressive native plants aren’t always a bad thing. If you have a large area, like a half acre or more, that you want to fill it with a variety of native plants, a native plant that spreads easily would be a good thing, especially if you’re trying to restore a piece of ground that’s choked with lots of non-native and noxious weeds. But if you’re working with a small space and you have neighbors on either side, you need to be careful what you introduce into your yard. If it’s aggressive, consider the consequences if it gets away from you.
