Spray Grass around Tree

Asked October 8, 2018, 1:53 PM EDT

Hello. I want to do a circle of mulch around my Maple trees in the yard and remove the grass at the base. Can I spray with a mixture of vinegar, epsom salt and a splash of dawn dish soap without hurting the tree?

Macomb County Michigan

1 Response


Strong vinegar solutions can burn tops off but do not kill roots. Vinegar could temporarily affect the soil pH and cause the maples stress. Epsom salts adds magnesium to soil, but soils in Michigan typically are high in that nutrient already. I do not know what dish soap would do to trees.

Your best bet is to remove as much grass by hand as possible, then mulch the area with 3 inches deep organic mulch. Keep the mulch pulled back from the trunk about 3-6 inches. Hand weed this area. When working around the roots, do not nick or cut into the surface roots or the tree bark. In summer when the weather warms add mulch so as to maintain the 3-4 inch depth. Do not pile it deeper because tree roots near the surface need air to remain healthy.

Alternatively you can just cut the grass as short as possible (without scraping the tree bark or roots) and put down the mulch. Eventually the grass will die under the mulch if you keep it covered.

Another method is to apply a selective herbicide that targets only grasses (not a broad leaf weed killer) to kill the grass. Always follow label directions. Be careful not to let the grass killer chemical get on anything else, including tree bark. Some common active ingredients in selective grass killer products are fluazifop, or quizalofop, or sethoxydim. ( MSU Extension doesn’t recommend brands or retailers). These are available from most large garden center and online.

I hope this information is helpful. Thank you for using our service.