pre-emergent weed killer for my turf grass

Asked March 18, 2013, 4:37 PM EDT

I am going to over seed and top dress (with compost) this spring but first I want to kill the weeds. Can you recommend a pre-emergent weed kill for my turf grass? Also how long after application do I need to wait before seeding? Also what is the best seed mix to use?

Thank you
Dick Gillet

Arapahoe County Colorado

1 Response

Dick,
a pre-emergent herbicide won't have any effect on established perennial weeds in the lawn - like dandelion or bindweed. It will prevent new weeds germinating from seed this spring. One good preemergent is pendimethalin (Pre-M, Halts, Pendulum). Apply in late March to prevent crabgrass, foxtail and other annual grasses as well as many broadleaved weeds.

You'd need to wait 4 months after using a pendimethalin product before overseeding with new grass seed. A good time to overseed a KY bluegrass lawn is early September.
The best seed mix to use depends on your situation and needs - if your lawn is KY bluegrass and you want to overseed with newer KY bluegrass varieties, there are newer varieties more tolerant of drought, high levels of foot traffic, shade (or use one of the fine fescues) or Necrotic Ringspot disease (or use perennial ryegrass)

Or just purchase a high-quality (not "economy") packaged blend of several named varieties of KY bluegrass that has 0.0% weed seeds

http://www.ext.colostate.edu/pubs/garden/03101.html

http://cmg.colostate.edu/gardennotes/562.pdf

http://csuturf.colostate.edu/pdffiles/Master%20Gardener/CSU%20TurfNotes/seed%20sod%20sources_TurfNot...