This pre-emergent weed stopper can be applied in early spring and late fall. It is safe to use around ornamental plants like roses and should be applied after all weeds have been removed from the beds. Broadcast the Weed Stopper at a rate of 1 pound per 200-250 square feet (a bed of 18-24 roses). You can broadcast over the mulch or directly on the soil if it is a newly prepared bed, adding mulch afterwards. Prohibits growth of the following weeds: Chickweed, Henbit, Spurge, Crabgrass, Dallisgrass and more.