For established lawns, early spring is the right time to apply Scotts crabgrass preventer. But if you just seeded your lawn or you are planning to seed, adjust the application time to ensure the herbicide doesn't stop your grass seed from taking root, since the product will stop different kinds of seeds from growing.

Does crabgrass preventer kill grass seed?

If you have used a pre-emergent herbicide or “crabgrass preventer” product within the last 12 weeks, it will kill any grass seed your spread on your lawn.

Can you plant grass seed after using halts?

If you have already put down Turf Builder plus Halts Crabgrass Preventer the directions state that you should not plant grass seed for 4 months after application. This would mean you will need to wait until the end of August to seed. ... Crabgrass seedlings about a week after germination.