Q. I'm having a very hard time killing crabgrass in my front lawn. I have put down Ortho Weed Killer twice this summer and it killed a little, but the crabgrass keeps coming back. Our neighbors' lawn is covered with it and they don't treat theirs. I think it may be coming from their yard. Is there something else I should be using to treat it?

—D.C., Richfield, MN

A. The best defense against crabgrass is healthy, dense turf. Since crabgrass is an annual, it doesn't overwinter, but the seeds do. So keep your lawn in peak form with proper mowing, feeding and watering, and in the spring, apply a corn-gluten based "weed-n-feed" product (sold under different brand names). The corn gluten contains an enzyme that prevents seed germination. If you can prevent the early plants from getting well established, your lawn can compete better early in the season and thicken up before the later crabgrass seeds sprout. Best of luck!

—National Gardening Association