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Crabgrass Identification Guide: Pictures, Types, and Lookalikes

Crabgrass (Digitaria spp.) is a notorious summer annual weed that invades thin, stressed lawns. Identifying it correctly—especially distinguishing it from desirable grasses like Bermuda—is the first step to effective control. This visual guide covers seedling-to-mature stages, two main species, and a side-by-side comparison with Bermuda grass.

What Is Crabgrass?

Named for its low, radiating stems that resemble a crab's legs, crabgrass is a warm-season annual that germinates when soil hits ~55°F (typically May–June), grows aggressively through summer, sets seed in August–September, and dies at first frost. A single plant produces up to 150,000 seeds, viable for years. It thrives in heat, drought, and compacted soil—exactly where cool-season turf struggles.

Key Identification Features

Growth habit: Prostrate, spreading from a central crown; forms dense, star-shaped mats.
Leaf blades: ¼–⅜″ wide, 2–6″ long, flat, pointed, light green to yellow-green. Rolled in bud (vernation).
Sheath & collar: Hairy or smooth depending on species; membranous ligule.
Seedhead: 3–13 finger-like spikes (racemes) radiating from top of stem, purplish when mature, up to 6″ long.
Roots: Fibrous, shallow; no rhizomes or stolons (unlike Bermuda).

Growth Stages: What to Look For

Seedling (Coin-Sized)

First leaf resembles a tiny corn plant—upright, rolled. Within days, side shoots emerge, creating the characteristic branched form.

Vegetative (Active Spread)

Stems elongate horizontally, rooting at nodes if they contact soil. Leaves unfold, widening the mat. Color is distinctively lighter than surrounding turf.

Reproductive (Seedhead Stage)

Late summer. Erect flowering stems rise above the mat, bearing the distinctive multi-spiked seedhead. This is the last chance to prevent next year's seed bank.

Two Main Species in North America

Smooth Crabgrass (Digitaria ischaemum)

Smaller: up to 15″ tall
Leaves: dull green, sparsely hairy only at base/sheath
Nodes: swollen, zigzag stem
Common in lawns, compacted edges, disturbed soil
Pre-emergent target: apply in Jan & May (split application)

Large / Hairy Crabgrass (Digitaria sanguinalis)

Larger: up to 3 ft if unmowed
Leaves: wider, pale bluish-green, densely hairy on both surfaces
Sheaths: conspicuously hairy
More common in gardens, fields, waste areas
Mulching suppresses germination effectively

Crabgrass vs. Bermuda Grass: Critical Distinction

Feature	Crabgrass	Bermuda Grass
Origin	Europe/Eurasia	African savanna
Life cycle	Annual (dies in frost)	Perennial (dormant in winter)
Spread	Seeds only	Rhizomes, stolons, seeds
Color	Yellow-green, lime-green	Blue-green to gray-green
Stems	Prostrate, radiating	Creeping, mat-forming
Leaf vernation	Rolled	Folded
Seedhead	3–13 finger spikes	3–7 spikes, narrower
Winter behavior	Dead brown mat	Dormant tan, regrows from roots
Desirability	Weed	Turfgrass (in warm zones)

Rule of thumb: If it pulls up easily with shallow roots and no runners, it's crabgrass. If it's anchored by tough underground stems, it's likely Bermuda.