Crabgrass vs Dallisgrass: How to Tell Them Apart

The quick answer: crabgrass is a summer annual that sprawls low across the lawn, roots where its stems touch the ground and dies with the first frost, so you beat it mainly by stopping seeds from germinating in spring. Dallisgrass is a perennial that grows in tough, upright clumps from short underground rhizomes and comes back every year from the same crown, so preventer alone will never get rid of it. Mixing the two up is the most common reason homeowners spend a season spraying and see the same clumps return. This guide shows how to tell them apart and what each control plan looks like.

In this guide

1. Crabgrass vs Dallisgrass Side by Side
2. Factor 1: Growth Habit
3. Factor 2: Seedheads
4. Factor 3: What’s Under the Soil
5. Factor 4: Timing and Life Cycle
6. Factor 5: Where Each Weed Shows Up
7. Other Look-Alikes
8. Why the Control Plans Differ
9. Herbicide Safety
10. Which Weed Do You Have? A Quick Decision Guide
11. Frequently Asked Questions

Crabgrass vs Dallisgrass Side by Side

Feature	Crabgrass	Dallisgrass
Life cycle	Summer annual; dies at first frost	Perennial; regrows from crown and rhizomes
Growth habit	Low, sprawling, star-shaped mat; stems root at nodes	Upright clump that widens over time; center may die out
Underground	Fibrous roots only	Short rhizomes with ring-like segments
Leaf blades	Light green; smooth (smooth crabgrass) or hairy (large crabgrass); about 1/4–1/3 in wide	Coarse, gray-green, wider than most turf; 4–10 in long unmowed
Ligule	Membranous	Membranous, about 1/4 in long
Seedhead	3–11 finger-like branches radiating from near the top of the stalk	2–10 widely spaced, often drooping branches on stalks 1–5 ft tall
Seeds	Small, along one side of each finger	Flat, egg-shaped, fringed with hairs; often dark
Germination	When soil reaches about 55°F for several days	Seeds germinate when soil reaches about 60–65°F; established plants regrow every spring
Main control	Preemergence in early spring, healthy dense turf	Dig out, repeated targeted herbicide, or renovate

Identification details above follow University of California Integrated Pest Management guidance on crabgrass and dallisgrass.

Factor 1: Growth Habit

Crabgrass spreads outward from a central point in a flat, star-like pattern, with stems that lie along the ground and root at the nodes where they touch soil. In a mowed lawn it often looks like a light green, sprawling patch that crowds out turf, especially along driveways and sidewalks where soil heats up first.

Dallisgrass forms a distinct, coarse clump that stands out from the surrounding turf. Over a few years the clump widens and the center can thin out, leaving a ring of coarse grass. In summer it grows faster than the lawn, so a few days after mowing the clumps are already taller than the turf around them.

Factor 2: Seedheads

Seedheads are the easiest above-ground clue. Crabgrass sends up stalks topped with slender, finger-like branches that radiate from near the same point, like the spokes of a small umbrella. Smooth crabgrass has about 5 to 7 shorter branches; large crabgrass has 3 to 11 longer ones.

Dallisgrass sends up tall stalks, sometimes several feet unmowed, with a few widely spaced branches along the upper stem. The branches often droop and the seeds are relatively large, flat and fringed with hairs. UC IPM notes the seedheads can lie almost parallel to the ground, so mowers often miss them. If you see tall seed stalks popping up just days after mowing, that points to dallisgrass.

Factor 3: What’s Under the Soil

When in doubt, dig. Use a trowel to lift one plant with its roots. Crabgrass has only fibrous roots and pulls out relatively easily, especially when young. Dallisgrass has a tough crown with short, thick rhizomes made of tight, ring-like segments. Those rhizomes are why it comes back year after year and why pulling the top off doesn’t kill it. UC IPM highlights this as the main way to separate dallisgrass from crabgrass, particularly since seedlings of the two can look very similar.

Factor 4: Timing and Life Cycle

Crabgrass germinates from seed in spring once soil temperatures hold around 55°F, peaks in midsummer, sets seed and dies at the first hard frost, leaving brown patches in fall. A single large crabgrass plant can produce enormous numbers of seeds that remain viable in soil for years, which is why prevention matters.

Dallisgrass greens up from the same clumps each spring, often earlier than warm-season lawns. It also spreads by seed. Because it is perennial, a clump you saw last year will be in the same spot this year, only bigger.

Factor 5: Where Each Weed Shows Up

Location in the yard and region of the country give useful hints. Crabgrass is found almost everywhere in the US. It favors thin turf, lawns mowed too short, bare spots, and the hot edges of driveways, sidewalks and curbs where soil warms first in spring. It is a classic sign that the lawn is not dense enough to shade the soil surface.

Dallisgrass is most common in the South, the transition zone and California, and it is a major weed in pastures as well as lawns. It tends to appear in areas that stay moist, such as low spots, near leaky irrigation heads and along areas that get frequent, heavy watering. It competes well with fertilized turf and tolerates drought and frost once established, so once a clump settles in, it rarely leaves without help.

Season matters too. If the grassy weed you are looking at is green and growing in March or April before your warm-season lawn wakes up, or it is still green after a frost that browned the crabgrass, it is far more likely to be a perennial like dallisgrass.

Other Look-Alikes

• Goosegrass: an annual with a whitish, flattened center and zipper-like seedheads; tolerates compacted soil.
• Tall fescue clumps: in bluegrass or bermuda lawns, coarse tall fescue tufts look like dallisgrass but lack rhizomes and the drooping seedhead.
• Bermudagrass: spreads aggressively by above- and below-ground runners with finger-like seedheads clustered at one point.
• Bahiagrass: perennial with a distinctive V-shaped seedhead of two branches.

For help with other weeds, see our guide to common lawn weeds identification.

Why the Control Plans Differ

Controlling Crabgrass

Because crabgrass starts from seed every year, the best approach is a preemergence herbicide applied a few weeks before it germinates in your area, then watered in with about half an inch of irrigation so the product activates. UC IPM lists active ingredients sold to homeowners, including dithiopyr, prodiamine, pendimethalin, trifluralin and benefin plus oryzalin. In many regions germination continues for months, so a second application may be needed; follow the label for timing and maximum yearly amounts. Our guide on when to apply crabgrass preventer covers timing by region.

Preemergence products also stop grass seed from germinating, so don’t apply them where you plan to seed, and wait for the interval on the label before overseeding. After crabgrass emerges, some postemergence products work on small, actively growing plants before they set seed, but effectiveness drops as plants mature and some populations resist certain chemicals. Hand-pulling young plants is effective in small areas. The long-term fix is a dense lawn: mow at the right height for your grass, water deeply and infrequently, and fertilize appropriately. See how to get rid of crabgrass and our roundup of the best crabgrass killers.

Controlling Dallisgrass

Dallisgrass is much harder. A preemergence herbicide can stop new dallisgrass seedlings, but it does nothing to the established clumps, which regrow from their crowns and rhizomes every year. UC IPM describes dallisgrass as very difficult to control, even with herbicides, and notes that mowing will not remove it.

• Dig it out: for scattered clumps, dig out the entire crown and rhizomes with a sharp spade or weeding knife, then fill and reseed the hole. Leaving rhizome pieces allows regrowth. Young plants are easiest to remove before they form rhizomes.
• Spot treatment: a nonselective herbicide such as glyphosate kills dallisgrass but also kills the surrounding turf, so it is a spot treatment followed by reseeding or patching. Follow the label for rates, protective equipment and replanting intervals.
• Selective herbicides: some products are labeled for dallisgrass in certain turf species, but options differ for cool-season and warm-season lawns, some are restricted to professionals, and many require several applications over multiple seasons. MSMA, once the standard, is no longer labeled for home lawns; our guide to MSMA weed killer alternatives covers current options.
• Renovation: in heavily infested lawns, killing the whole area and replanting may be the most practical option.

Dallisgrass often thrives where watering is frequent and heavy, so adjusting irrigation and building dense turf help prevent reinfestation. For a full plan, see how to get rid of dallisgrass.

Herbicide Safety

The label is the law. Read the entire label before buying and before each application, confirm the product is labeled for your turf species and the target weed, use the stated rate, and wear the listed protective equipment. Keep children and pets off treated areas for the time the label specifies, do not apply before heavy rain or near water, and never spray in windy conditions where drift can reach gardens. Store products in their original containers out of reach of children.

Which Weed Do You Have? A Quick Decision Guide

• If the plant is low and sprawling, roots at the stem joints, and died back after the first frost, you have crabgrass. Plan a preemergence application next spring.
• If it forms upright, coarse clumps that come back in the same spots, with short ringed rhizomes underground, you have dallisgrass. Dig, spot-treat or renovate.
• If seedheads have fingers radiating from near one point, think crabgrass or bermuda. If branches are widely spaced along a tall stalk and droop, think dallisgrass.
• If you’re still unsure, take a sample with roots to your local extension office for identification.

For a year-round lawn calendar, visit the lawn care guide.