Wilson WeedOut can be used anytime weeds are actively growing. Ready-to-spray formula - no measuring or mixing. One 1-L bottle will control up to 200 individual weed plants. Kills weeds to the root with no re-growth. Visible effects (twisting, wilting, etc.) within 24 hours. Effective against dandelion, plantain (broadleaf and narrow-leaved), ragweed, fall hawkbit, hawkweed, orange hawkweed, cinquefoil, white clover, and black medic. This product will not prevent new weeds.