When Can I Seed After Preventing Crabgrass?
I hear that question quite a few times this time of year. I have two answers depending on the size of the lawn area that needs new grass seed. However, before I give those two answers here is a quick rundown of crabgrass prevention 101.
Scotts Turf Builder plus Halts Crabgrass Preventer and Scotts Lawn Pro Step 1 contain our best crabgrass preventer to provide prevention for around 4 months. The directions state that you should not plant grass seed for 4 months after application, which means you will need to wait until the end of August to seed. We have a different crabgrass preventer for folks who want to seed in spring and prevent crabgrass. Scotts Starter Fertilizer plus Crabgrass Preventer and Scotts Lawn Pro Step 1 for New Seeding provide crabgrass prevention while allowing you to plant grass seed at the same time. (Note: the crabgrass prevention is not generally as good as Turf Builder plus Halts and Step 1, however it is your best choice if you want to seed in spring.)
Now here are my two answers:
1). If you only have a few small areas you want to seed, I have seen folks get around the fact that they have a crabgrass germination barrier in those spots by cultivating the soil to a 4 inch depth (to disrupt the crabgrass barrier), then mixing in an inch of compost like Scotts Turf Builder Lawn Soil, and then seeding with Scotts EZ Seed.
2). If you have a large area you want to seed, the first recommendation is not practical, so you really need to wait until early fall to seed.