Knowledgebase
Weeds and Moss... Help! #769890
Asked August 30, 2021, 3:12 PM EDT
Carver County Minnesota
Expert Response
Weeds and moss grow in a wide range of conditions. From your pictures and your soil test, you may need a total lawn renovation. First you could kill weeds this fall with a herbicide such as glyphosate. Weeds are storing energy in the fall and readily take up herbicides. A pre-emergent treatment in the early spring would be a good idea to kill weeds that seed, such as crabgrass.
The failure of the grass means that weeds take over. Your pH is higher than ideal but still okay for grasses. You could add a sulfur treatment to bring the pH down a bit in the spring. Sulfur needs warm ground and is best applied in spring.
It doesn’t look like there is a lot of thatch but the soil may also be compacted. If so, aerating is a good practice. Dormant seeding is an option. For more details see the websites.
1. https://extension.umn.edu/lawn-care/renovating-lawn-quality-and-sustainability
2. https://hortnews.extension.iastate.edu/1995/5-12-1995/moss.html
3. https://extension.umn.edu/yard-and-garden-news/success-fall-lawn-seeding-depends-rain
4. https://extension.umn.edu/lawns-and-landscapes/lawn-care
5. https://extension.umn.edu/planting-and-growing-guides/lawn-care-calendar