Hi Patricia,

Thank you for reaching out to UVM Extension Master Gardener Helpline.

You can find a couple of great resources on managing red sorrel, or sheep sorrel, here: 

https://extension.umd.edu/resource/red-sorrel-sheep-sorrel/

canr.msu.edu/ipm/diseases/red-sorrel?language_id=

Red sorrel tends to thrive in soils with low pH (acidic) and low fertility. I would recommend getting a soil test to see what current conditions are so that you can adjust accordingly to create more favorable conditions for grasses or other desired species to outcompete the red sorrel. Here is what the MSU resource suggests:

"Red sorrel is easily managed with judicious fertilizer applications and consistent mowing at 3+ inches. Dense turf is a very effective deterrent. Red sorrel is often an indication of acidic soils. Liming toward a neutral pH will help encourage the turf and remove red sorrels main advantage."

Generally, a dense, healthy turf is effective at deterring red sorrel over time and should do a good bit of the work for you.

I hope this helps, and happy gardening!