Invasive Plants, Part 3: How I Eliminated Goutweed in my front Garden

Missed the first two posts? Read them here: Part 1 and Part 2

After years of battling Goutweed in our front garden, I decided to take drastic measures to get rid of it once and for all. The tactic I decided to use? I smothered it! That sounds rather vicious, but in reality, it was more work than anything else. 

Here's the method I used:

• Clear the area removing all the perennials and any small shrubs. Trees obviously have to remain as do large shrubs. 

Aggressive plants will sometimes shoot their roots right through those of other perennials. It's, therefore, necessary to lift each plant, wash the roots and inspect the root ball carefully. The root ball may need to be divided into smaller pieces to eliminate problems. 

Once the lifted perennials are completely cleared of invaders, you can replant them in another spot. Just be extremely careful with this step. The last thing you want to do is transfer an invasive plant to another area of the garden.

It's hard to show, but in the picture above you can somewhat see that orange daylilies have infiltrated a clump of hosta. The only way to separate the two plants is to dig up the clump of hosta. Then you need to clear enough dirt from the roots to see what's going on. Once you identify the two types of roots, you can carefully separate the two plants.

• Once the flowerbed is completely cleared and the perennials you want to keep have been set aside, go back and remove all the invasive plant roots you can find. Again, do this very carefully. Often any remaining root segments have the potential to produce new plants. It's best to dig back over an area two or three times to ensure you have removed as many of the invasive roots as possible.

• To make it difficult for any missed root segments to regrow, you want to create a light barrier. 

I just happen to have President's Choice compost bags on hand, but any brown compost bag will do.

• To make a light barrier I decided to use brown paper compost bags and cut them up. Why compost bags? They are biodegradable and have less printer's ink than newsprint. A compost bag when cut open also creates a big, solid piece of paper. That large piece of paper covers so much more ground than an open spread of newsprint would.

You could use cardboard– it would work just fine, but you'll have to remove any tape or staples that hold the box together. These materials wouldn't break down and staples could pose a risk later on.

• With your scissors, cut along the outside corner of the brown paper bag all the way to the bottom. When you get to the bottom, turn the scissors and follow the bottom of the bag all the way around until you've cut off the whole bottom section of the bag.

With the bottom removed, you should now be able to open the compost bag into one big rectangle of heavy brown paper. Don't throw away the bottom of the bag! As you will see in a minute, it has a use.

• Try to chose a windless day to avoid frustration with this next step. The goal is to cover the entire area with a solid barrier that will deprive light to any remaining roots.

• Lay the open piece of brown paper on the ground. Use a small stone or a small pile of mulch in each corner to hold the paper in place while you work. I used a single layer of paper, but a double layer of brown paper would be even better.

• Overlap the pieces of brown paper by at least six inches. If you leave gaps, light can reach through the gaps.

Here is how I dealt with a small tree in the middle of my flowerbed. I cut the bottom section of the bag in half. Then I cut a U-shaped hole in the centre of each of the two pieces of brown paper. In the final step, I overlapped the two pieces together around the base of the tree.

Once I had the tree surrounded by paper, I went back to using larger sections of the paper.

Once the paper is laid out on the ground, cover the whole area with natural cedar mulch. Don't be stingy! Make that layer of mulch at least 2-4 inches deep.

The mulch will do a number of things. Along with the paper, it helps to block light. The weight of the mulch will deter fresh sprouts. It will also help keep the paper a bit dryer. And finally, the mulch will make the area look presentable while the paper does its work.

Goutweed can really take over as it has done here in this garden.

Gardening in this area is now on hold for a month or even more. If sprouts do make it through the paper and mulch, dig them out. Create a new patch of brown paper to cover the hole. Add a fresh layer of mulch on top of the patch.

The limitations of this method:

Creating a light barrier may not work for every invasive plant or in every garden situation. 

Large shrubs can be surrounded with paper much like trees, but extra vigilance is needed as invasive plants can hide out at the base of a shrub.

If you deprive a plant of light in one area, it can travel to another. Should you decide to use my tactics, I would recommend you find a way to block the invasive plant in question from running into a new area of the garden. The easiest way to do this might be to dig a deep and wide trench around the problem space.

This method has worked pretty well for me and it is organic. I did have a few shoots make it up through the paper, but I removed them and patched the holes. After about a month and a half, I didn't have any new signs of the dreaded Goutweed.

My struggles are far from over. There is another patch of Goutweed in the backyard. Like housework, a gardener's work is never done!

Go back and read Invasive Plants Part 1 and Part 2.

Bookmark this post with a Pin.