Scotts® Halts® Crabgrass & Grassy Weed Preventer prevents the germination of listed lawn weeds so you can enjoy your lawn. In early spring, apply when lawn is dry to prevent the germination of crabgrass, foxtail, spurge, barnyardgrass, fall panicum, goosegrass* and oxalis all season long (*for goosegrass control, repeat application in 8 weeks). Apply in the fall (August-October) to prevent moss (except in California), or to prevent the germination of Poa annua, henbit, corn speedwell, and chickweed. Scotts® Halts® Crabgrass & Grassy Weed Preventer is for use on all lawns and grass types (with the exception of Dichondra or Bentgrass lawns). Rain, snow, or freezing weather after application will not affect the performance of this product. Please note, this product controls crabgrass in its early stages of growth. It does not control mature crabgrass and other existing weeds. One 20.12 lb. bag of Scotts® Halts® Crabgrass & Grassy Weed Preventer covers 10,000 sq. ft.