Yarrow, also known as bloodwort and carpenter’s weed, has its good side and bad side. The plant is an easy-to-grow member of the aster family, it produces lovely white, yellow or pale purple flowers all summer, thrives during drought and spreads rapidly via underground stems and seeds. The rapid spreading is the bad side, it makes yarrow an invasive plant that gardeners usually regret planting. To get rid of yarrow, here’s what you will have to do-
Pulling the yarrow plants up by hand or hoeing them up by the roots is a non-chemical removal option. Labor intensive and you may have to keep after the sprouts for a few weeks until every last underground root has been pulled up. Some seeds may lie dormant in the soil until the following spring, so the hand-pulling may continue for a year or more before all the yarrow has been eradicated.
Yarrow seeds are often sold as part of a wildflower seed mix or planted as filler plants in flower beds and grow amongst desirable flowers, so many gardeners think that a chemical solution can’t be used to get rid of yarrow. It can with this little trick; Cut the bottom off a plastic gallon milk jug (several milk jugs will speed up the eradication via chemical process) and place the jug over the yarrow you want to kill with an herbicide. Spray the herbicide of choice through the milk jug top opening and onto the yarrow. Leave the milk jug in place until the herbicide stops dripping, then move it over to the next undesirable yarrow. This process is time consuming, but it will keep the herbicide off of surrounding plants while killing the undesirables.
Chemical-free herbicides are also on the market, most have a base of vinegar and clove oil and won’t harm pets or children. The milk jug cover trick should still be used with a natural weed killing product so surrounding plants won’t be unintentionally killed.
50% or More
If invasive yarrow has taken over 50% or more of garden, it would be best to kill everything with herbicide (chemical or non) and start all over. Saturate the plants with herbicide and cover the area with black plastic for a month so the heat will ‘cook’ whatever the herbicide missed. Prior to re-planting the site, till and rake the soil to remove debris which may still contain chemicals, work organic matter into soil and have the soil tested.
University of Maryland Medical Center