Large crabgrass (Digitaria sanguinalis) is a summer annual weed. It is also called hairy crabgrass.
Crabgrass has a prostrate growth habit; the lower stems branch out and spread across the ground, and it can grow upward to 2 feet tall. The stems have swollen nodes; plants can develop roots at the nodes and form small colonies. The leaf blades have small hairs. Roots are fibrous. Flowers have 3 to 5 or more spikes. Crabgrass dies after the first frost in the fall.
Crabgrass reproduces primarily by seeds, which germinate from spring through late summer when the soil temperature is above 55°F for at least 3 consecutive days.
Conditions that favor growth
Thin turf with bare spots; mowing a lawn too short will favor crabgrass.