4 easy tips.step 1. U only have one time in the year to try to prevent crabgrass.the best time is in the early spring.febuary-april (apply crabgrass prevetion) This feeds and stops the crabgrass from taking over the lawn. step 2 apply in late spring april-june (apply weed control) This feeds the lawn and also kills dandelions, and clover and other broadleaf weeds.step 3 apply in the late summer june-august ( apply insect contol & fertilizer) this will feed and kill lawn damaging insects on top and below the surface.step 4 apply in the fall august-november(apply fertilzer) this renews and strengthens your lawn before winter sets in. four easy tips for a jammin looking lawn.