(Bishop’s goutweed, ground-elder)
Goutweed is a familiar problem to gardeners. It is an edible and medicinal groundcover that thrives in any light conditions and most soils.
It quickly integrates itself into gardens and crowds out any other plant that is not a tree or shrub, outstaying its welcome and creating boring-looking monocultures that are difficult to remove. Goutweed can travel underneath concrete or stone pavers for up to 6 feet with its creeping rhizomes.
To remove goutweed, I give a “first pass”, removing all plants and roots. In a well established patch, I'll clear about 1 square meter an hour but I don’t leave much behind. Then, for the rest of the season, I return every week or two and remove the goutweed that I missed. Subsequent “passes” take much less time than the first and the whole property can be done in an hour. I have cleared gardens of goutweed permanently and I can give references.
Doing it yourself
There are several ways to treat goutweed.
Regular mowing will weaken the plants and slow their spread, though this won’t eradicate them entirely. A string trimmer can slow the spread of goutweed until you are ready to take further action.
I have found this to be the most effective method. I find it helpful to chop through the plants with a shovel if the rhizomes are too snarled together to disentangle. Then I use a clawed tool to remove the spaghetti-like roots. After taking out all you can find, keep a steady schedule of one hour a week taking out the bits you’ve missed before they can restore the colony. Take heart! The second passes will be much easier than a first pass, even if you’ve waited a couple of years and let it go. It will take about five or ten years for a patch to recover completely from a first pass.
Goutweed can be greatly slowed down if you can place an impermeable vertical barrier into the top 8” of soil. You can buy 8” “lawn edging” at many garden centres and bury it leaving 2 inches above the ground. Use it to protect your progress from the creeping influence of adjacent goutweed, or to keep out the goutweed in your neighbours’ property.
One good thing about goutweed is that it encourages people to mulch who should be mulching anyway.
I have seen good results from people who lay down a strong, lightproofbarrier for a couple of seasons, as long as you don't let the goutweed grow around the sides of the barrier and into the mulch.
If it already has grown around the edges and into the mulch, it is usually very easy to sift the roots out of the loose rotted mulch and new soil. Make sure to weed under the barrier and continue to get the bits you have missed.
Disposing of goutweed
The city of Halifax’s composting facilities get from 60-80 degrees C from the rotting process, which is adequate to kill the goutweed. I suggest you put it out for the city. Other ways to kill goutweed are to let it dry out completely, to burn it, or through anaerobic digestion. If you choose to burn outdoors be sure to obtain a permit.
I cannot make any claims of dealing with Japanese knotweed but I do enjoy steaming the sprouts in the springtime and serving them with a little butter and salt.
Clearing a property like this might start at $1000.