restoration of knot weed infested areas

Asked March 28, 2019, 9:10 AM EDT

I have been trying to get rid of knot weed through injection and spraying. After a few years of this I would like to try and plant some hardy, fast growing grass in the more level areas and on some steeper grades some kind of shrub or thick cover to help with erosion. Do you have any suggestions for grasses and shrubs for restoration of these areas? I plan on trying to spot treat the shoots of knotweed as they reappear and maybe in the fall before frost retreat any larger patches of knotweed that I missed last year.

St. Louis County Minnesota

1 Response

Hello and thank you for contacting AaE.

Treating knotweed is a multi-year project that I'm very familiar with and I commend you for your effort. Retreating is best before they flower and set seeds. But if you want to wait until fall, you could keep an eye out for flowers and cut them off before they set seeds.

There are lots of choices to consider depending on whether you have sun or shade, moist or dry, clay or sand. But here are a few ideas.

On slopes you could consider creeping juniper (Juniperus horizontalis) which prefers full sun, fragrant sumac (Rhus aromatica) (full sun to part shade) or yews (Taxus sp.) (tolerates full sun but will do well in full shade). Also the grasses like sand dropseed (Sporobolus cryptandrus) (prefers sun) or switchgrass (Panicum virgatum) (sun or part shade).

Feel free to send in a new question if you want to know what would grow in your specific conditions. Good-luck!