What can be done to control Bishop’s weed?


Bishop’s weed is a battle here. What can be done? The entire property is bordered with it and it tries to creep into lawn and other areas. I try to pull it, weed wack, mow and do some occasional chemical spray. I would like to come up with a game plan to fight it all four seasons to knock it back. Also wondering if there are any horticulturist in area that may also be able to consult with?


Jonathan Foster, Home Horticulture Outreach Professional

I’m sorry to hear you are dealing with bishop’s weed–it’s an enormous headache in the garden.

I will refer you to a previous Ask an Expert response by my colleague Kate Garland, focusing on the non-chemical intervention approach, as well as the State of Maine’s Natural Areas Program page on bishop’s weed, which includes suggestions for herbicidal treatment, as well. As the state website states, because bishop’s weed has such an aggressive underground structure, it’s an excellent candidates for systemic treatments like triclopyr or glyphosate. If you do choose to use a treatment, please read carefully and follow conscientiously all instructions on the container. More is not better, as these are non-specific herbicides and will kill plants they come into contact with, both unwanted and wanted.

Depending on your set up, I have also had good luck clearing an area of the plant, then sinking edging material down to at least 18-24″ as a barrier against incursion from non-cleared areas. Again, this may or may not be feasible for your space, but it does provide a barrier to protect any areas you’ve labored hard to clear out–if the lawn is too large, consider this options for perennial beds. This also gives you the freedom to work on the pest in chunks and make progress without being paralyzed by trying to fight it off everywhere at once.

The gardener’s best friends, patience and diligence, will be your allies. As Kate says in the link above, removing bishop’s weed is hard work, but doable.

Good luck, and happy gardening.