Smooth Crabgrass is a summer annual grass in the Poaceae family. This warm season lawn and garden weed germinates in the spring and grows through the summer producing seed. The seed germinates in the late winter to early spring. It has a ground-hugging clumping habit and can root in the ground at its leaf nodes making it very hard to pull up as it grows. To manage the weed try to hand weed it when it is small before it has sent down secondary roots. Mulching garden beds can slow germination. It is killed off by frost. This plant is found in disturbed areas, lawns, meadows, sidewalk cracks and along roads in most states of the US. It tends to prefer heavier soils and tolerates full sun, part shade, heat and drought.
Curated pairwise relationships between this plant and others in the library — who feeds
whom, who competes, who confuses the pests. Green reads as a good pairing, red as one to avoid.
No curated interactions recorded for this species yet.
Also noted by NC State
Related species the NC State Plant Toolbox flags for this plant — look-alikes to tell
apart, and plants that play a similar role in a planting. Ones we carry in the library are linked.
Full sun (6 or more hours of direct sunlight a day) | Partial Shade (Direct sunlight only part of the day, 2-6 hours)
Soil texture
Clay; Loam (Silt); Shallow Rocky
Soil drainage
Good Drainage | Moist | Occasionally Dry
Growth rate
Rapid
Maintenance
High
Form & Appearance
Habit / form
Ascending; Prostrate; Spreading
Leaf color
Green
Leaf type
Sheath
Leaf shape
Linear
Leaf margin
Entire
Leaf size
3-6 inches long, < 1 inch wide
Hairs present
Yes
Leaf detail
Flat green leaves are up to 4 inches long and 1/4 inch wide. Hairs are present on the sheath base. The ridged sheaths are open at the front and often have a few long hairs.
Flower form
Insignificant; Raceme
Flower detail
Flower clusters form at the end of flowering stems with small egg-shaped spikelets that are generally in pairs up the stem.
Bloom time
Fall; Summer
Fruit color
Brown/Copper; Purple/Lavender
Fruit type
Achene
Fruit size
< 1 inch long
Fruit detail
The spikelets turn brown to purplish and form dark brown to black oval seeds.
Stem detail
Stems are light green to purple near the base. The lower stems are mostly covered by sheaths.