How to Get Rid of Invasive Plants (Without Making the Problem Worse)

nvilu7

Jul 14

8 min read

Updated: Aug 31

Dealing With Invasive Plants, Part 2

mid century ranch with invasive English Ivy and Himalayan Blackberry in its yard

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In Part 1 we learned how to tell the difference between ordinary weeds and invasive plants. Now comes the important part: getting rid of them before they take over your yard.

How Invasive Plants Get Into Your Yard

Invasive species travel to new areas in many ways. The most common is human intervention. Contaminated mulch, sand, gravel, and construction equipment often carry seeds or plant fragments from one region to another; mowers, graders, and hikers transport seeds on clothing, boots, and pets.

Additionally, seeds can be spread long distances by wind, water currents, or by being eaten and transported by birds and animals. Some species spread via aggressive root systems (suckers/rhizomes) that can grow up to 50 feet away from the original plant (eeek!).

It’s very possible that your new invader has been happily growing in your neighbor’s yard or on a commercial property in the next block, and you never noticed it until it got to your space.

So, if you see plant invaders in your yard, don’t blame yourself. Invasive plants don’t recognize property lines. Their primary directive is to survive, thrive, and reproduce. Fortunately, you have something they don't: the ability to notice them before they take over.

The sooner you act, the easier the job becomes.

Young invasive plants are dramatically easier to control than mature infestations.

How to Find Them Before They Spread

After you’ve compiled your Invasive Plant Watch List as described in Part 1, familiarize yourself with descriptions and photos of your plant enemies. Then, conduct a deliberate and careful grid search of your property—the horticultural version of what you’ve seen countless times on TV cop shows.

Any time during your region’s growing season is a good time to start. Conduct your grid search periodically through the season so you can eliminate noxious weeds and invasive plants before they become established.

One of the themes you'll see throughout Little Green Home is that small problems rarely stay small when ignored. Invasive plants are no different. Spending fifteen minutes every few weeks walking your yard is far easier than reclaiming it after years of neglect.

I’ve done both, and believe me, a periodic grid search is much easier.

As you walk your grid, keep your eyes open. Are there any new and uninvited plant interlopers? Anything growing in a place where nothing was growing before? Any vines, leaves, branches, stalks, or twigs growing in underneath an existing plant, shrub, or tree, or peeking under, over, or through a fence? Anything new growing up one of your trees or shrubs?

Take a picture of every plant that’s new or unfamiliar and check it against the list you’ve compiled. Compare your pics against the photos on your municipality’s website. If you didn’t plant this newbie, it’s an invader.

Don't assume every unfamiliar plant is invasive.

Many native plants emerge in unexpected places. Always identify a plant before removing it.

Don’t Just Pull Them Out

Once you’ve identified the noxious weeds and/or invasive plants in your outdoor space, the next step is getting rid of them.

In my experience, most people assume that they can simply pull out the offender by the roots and call it good. Sadly, pulling a noxious weed or invasive plant out of the ground by the roots is a temporary solution, because their root systems are deep, extensive, and come back year after year like your treasured perennial plants.

In other words, noxious weeds and invasive plants have evolved to defy your efforts to weed them out.

Invasive plants’ root systems are also the reason why mowing over them isn’t going to cut it, either (haha). They may be gone from the surface, but those root systems continue to grow underground, seeking a location where they can surreptitiously break the surface.

So, don’t bring a knife to a gunfight. Revisit your state’s noxious weed/invasive plant list to see what they recommend to get rid of your plant invaders once and for all. The sooner you can eliminate them, the better. If you do, the plants you choose to grow and the native plants growing in your neighborhood will not have to compete with the invaders for resources.

Unfortunately, the solution for eliminating a noxious weed or invasive plant is not often obvious.

Before You Reach for the Shovel

Different invasive plants require different control methods. Some respond well to repeated cutting. Others require digging, smothering, or targeted herbicide treatment. Before starting, check your state's Department of Agriculture recommendations for the specific plant you're dealing with.

My English Ivy Battle

English Ivy’s leaves and berries are toxic to humans, dogs, cats, and horses, causing vomiting, abdominal pain, diarrhea, and hypersalivation. Contact with its sap can cause skin irritation, rashes, and dermatitis. Additionally, when left unchecked, English Ivy will grow into and “overwhelm” (“kill” in botany-speak) trees and woody shrubs. It will also “displace” (another botanical equivalent of “kill”) ground vegetation.

It had to go.

When I moved in, English Ivy covered half of my yard. I discovered that this housewarming gift came courtesy of the neighbors on either side of my property, where it grows in profusion. My neighbors deal with it by simply mowing over whatever is on the ground and leaving the rest to thrive.

So, I had two reasons for getting rid of the ivy. First, I didn’t want to expose myself, my pets, and my future garden to such a toxic invader. Second, I didn’t want to be the kind of neighbor that’s OK with allowing a well-known noxious weed to grow unchecked.

But if pulling the plant out by the roots and mowing it down are ineffective, how do you get rid of a noxious weed or invasive plant like English Ivy?

Why I Ended Up Using Roundup

Oregon’s English Ivy profile document states that “no biological control agents are available.” What that means in English is that English Ivy has no known natural enemies and that you have to use chemical means to get rid of it.

Or, as a seasoned gardener-for-hire succinctly told me, “The only way to get rid of ivy is Roundup.”

Since at the time I was in the early stages of recovering from shoulder surgery, I hired that gardener to make the first pass at getting rid of the ivy, which he did with a thorough application of Roundup.

A month later, I went out in my yard and discovered to my horror that the ivy was growing back. I was reluctant to use Roundup. An acquaintance suggested using horticultural vinegar, which is available in concentrations ranging from 20 to 50%.

After buying a gallon of vinegar in a 45% concentration, I wisely read the label before using. I found out that vinegar in high concentrations is extremely dangerous. Exposure can cause severe skin burns and eye damage, so safety gloves and goggles are highly advised.

After I am safety-gloved and goggled up, will the vinegar kill the English Ivy?

Nope. Highly-concentrated vinegar only kills a noxious weed’s surface growth, not the root system.

Then I found Himalayan Blackberry in my back yard. Like the ivy, it is also considered a B-rated noxious weed in Oregon.

I emailed the Oregon Department of Agriculture (ODA) to ask for their advice. After some hemming and hawing, the botanist told me that Roundup was the only sure way to get rid of the English Ivy and the Himalayan Blackberry for good, and that it would take years of consistent spraying to do it.

My gardener was right.

One thing I’ve learned since then is that state agriculture departments rarely recommend one universal solution on their websites because the best approach depends on the species, the size of the infestation, and where it's growing. If you're dealing with an established invasive plant, it's worth emailing your state's Department of Agriculture for advice specific to your situation.

I understand that many gardeners prefer not to use glyphosate-based herbicides, and that's a completely reasonable decision. After researching my options and consulting with ODA, I decided that carefully targeted applications of Roundup were the most practical way to eliminate two established invasive species on my property. Whatever method you choose, always follow the label exactly and wear appropriate protective equipment.

Because I’ve been consistent in my approach, my bi-monthly Roundup patrol takes about 15 minutes per session, well worth it to be rid of the ivy and blackberry. In the end, I found that consistency is far more effective than intensity.

The vinegar is still sitting in my garage. I recently discovered that it’s great for eliminating mushrooms, which grow in profusion in my yard after warm, wet winters.

How to Prevent Invasive Plants from Coming Back

The best prevention against an aggressive plant invasion is to watch for new or uninvited plant interlopers, quickly identify noxious and invasive species, act promptly to remove them, and carefully dispose of all parts of those plants to avoid accidental spread.

Here are some additional tips:

Never compost any part of an invasive/noxious plant; even a plant fragment or a single seed is capable of growing an army.
Never place any part of an invasive/noxious plant in your plant recycling bin. I would wait until the ivy and blackberry in my yard was truly dead post-Roundup, bag it separately, and put it in the garbage.
Check gardening tools after use to remove suspect seeds and plant fragments and dispose of them properly.
When hiking, avoid areas that are infested with invasive species; look at your state’s invasive plant list to see where they are distributed in your area. Post hike, wash mud and plant parts off hiking boots, clothes, and tools and dispose of them properly to avoid spreading seeds.
As I did with my gooseneck loosestrife, plant invasive species in pots that are tall enough that the plant’s roots stay contained in the pot. Deadhead these plants before their flowers mature and disperse their seeds.
If offered free plants or cuttings, make sure you know what you’re getting before accepting them. And don’t say yes just to get someone to stop offering! A neighbor repeatedly offered (unasked, I might add) to share his invasive bamboo with me. I politely declined the first six times he offered, then emphatically declined with expletives.
Check your state and local guidelines before buying new plants, and plant natives whenever you can.

Invasive plants are persistent, but they aren't unbeatable. Learn what's growing in your yard, deal with problems while they're still small, and stay consistent. Your future self—and your garden—will thank you.

Planning a lower-maintenance yard?

Download my free guide, How to Select the Right Tree, and avoid creating tomorrow's yard problems today.

Invasive Plant-Fighting Equipment

Gardening gloves: I use these gloves for my bi-monthly Roundup sessions and then throw them in the wash. But, if you want extra protection, Wells Lamont makes excellent heavy-duty rubber safety gloves.
Safety goggles: these are adjustable for a snug fit.
Pump Sprayer: I learned the hard way that cheap pump sprayers aren't a bargain. After my $12 sprayer failed in just two months, I bought this one. Three years later it's still going strong, and I bought a second one for fertilizer. It's one of those tools that's worth buying once.
A fantastic garden kneeler/seat.
FELCO pruners, my tried-and-true gardening partner.
Waterproof garden boots.
Gardening sleeves—sun and scratch protection and available in a variety of colors and prints.