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 insure 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.
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 cut away, 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.
Once I had the tree surrounded with paper, I went back to using larger sections of paper.
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.
My struggles are far from over. There is another patch of Goutweed in the backyard. Like housework, a gardener's work is never done!
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