I have a customer who has an estimated 10-15% crab grass in his back yard. It's a new home and the back was seeded. Front looks great, no crab grass or anything else, but it came from sod. If I overseed now with a slit seeder, will that make the crabgrass be gone for next year? Will it make his lawn look better for the remainder of this year? Is this a better way to go than just to wait 'til next year and do pre-emergent treatment? How can I sell him on this over-seeding if this is the thing to do? I'm thinking I'll have to charge at least $150-175 to make it worth my while as the dethatcher/seeder is around $50 to rent and the seed may be about $40-50 for that area ( about 20,000 sq ft). Or should I charge a lot more/or less?