I have recently put in a bid for a job for a complete restoration of a lawn. I will be using round up to kill off the existing vegetation but my question is. I will be rototilling the ground, after grading/seeding/, what happens if I get massive amounts of weeds as well as a healthy lawn? Also, should I use pre-m before july to prevent crabgrass from germinating? Its in direct sun. I'm using a TTTF mix from Lesco called Eco-Sential Survival Seed mix. I had this problem last year, and wanted to prevent it this time.