LawnSuite guide: Summer grass (crabgrass) in lawns: a warm-weather annual weed
Use this LawnSuite guide to recognise the problem before deciding what to do. Summer grass is an annual grassy weed that moves into thin and bare patches as the weather warms. A dense, well-kept lawn is the best defence.
How to spot it
Summer grass, also called hairy crabgrass (Digitaria sanguinalis), is a low, spreading, tufted annual grass. It's commonly found in lawns and gardens.
When it shows up
It germinates as the soil warms in spring and flowers from about December or January through to May. As an annual, it comes back from seed each year.
How it gets in
It spreads by seed, and mowing can carry that seed around. Weed seed also arrives on topdressing soil and manure. Bare patches give summer-growing weeds, including annual grasses, ideal conditions to establish, for example where winter grass has died off.
Your grass type
A buffalo lawn kept in good condition forms a dense turf that checks vigorous weeds like crabgrass.
Lawn care that helps
Keep the lawn dense and well kept, and fill bare patches so there are fewer gaps for seed to land in. If you're renovating in spring, plan the order: scarifying or cultivating after a pre-emergent can disturb the treated surface.
If you use a product
Use a selective herbicide whose label lists your turf type and summer grass, and follow the label. Time it to the soil warming in spring, not a calendar date.
Keep reading
- When Should You Dethatch or Scarify an Australian Lawn?
- Crowsfoot grass
- Winter grass
- Nutgrass
- All lawn problems
Sources: Australian government and university pages, summarised in our own words.
Not sure it's summer grass?
Create a free LawnSuite account in your browser and photograph the patch. Photo diagnosis uses Google Gemini vision to identify the likely weed, pest or disease and shows a confidence score for each result, so you can match it to the signs on this page before you treat.