Crabgrass is probably the most hated grassy weed in home lawns. Fortunately, it is an annual weed. Annual grass weeds germinate from seed, grow vegetatively, produce seed and die within a 12 month period. In addition to crabgrass, there are a number of other annual grass weeds, such as goosegrass, foxtail, barnyardgrass, fall pancium and annual bluegrass. Crabgrass and other annual grass weed normally germinate around early April. Hence, March is the perfect time to apply crabgrass preventer so that crabgrass seeds will not germinate.