Crabgrass continues to germinate over several weeks from spring into summer. While crabgrass germination begins in the spring, the weed doesn't become highly visible in lawns until summer. Crabgrass is a low growing, spreading plant with light blue-green foliage. Seedheads appear as several finger-like projections atop upright stems. Crabgrass grows rapidly during warm summer weather.
Growth slows with the arrival of cooler temperatures in late summer.
Plants are destroyed with the first hard frost in the fall. However, before it dies, a single crabgrass plant can produce up to 150,000 seeds. The best way to prevent crabgrass infestations in lawns is to maintain a thick, healthy lawn through proper mowing, irrigation and fertilization. Crabgrass will have a difficult time germinating and surviving in a dense turf. Gardeners who have had crabgrass problems in the past will need to apply preemergence herbicides in the spring.