Smooth Crabgrass

About Smooth Crabgrass

Smooth crabgrass (Digitaria ischaemum) is a summer annual grassy weed that germinates when soil temperatures reach the mid-50s Fahrenheit — which in Middle Tennessee means it starts emerging around the March 15th window that drives our entire pre-emergent timing schedule. Here is the honest truth about crabgrass in Middle Tennessee: almost every homeowner who calls about "crabgrass" actually has dallisgrass or Johnson grass instead. True crabgrass is a summer annual — it germinates in spring, grows through summer, and dies with the first frost. Dallisgrass and Johnson grass are perennials that look similar but persist year after year and are dramatically harder to control. If your "crabgrass" is in the same spot every year and seems to come back from the roots, it is not crabgrass. Actual crabgrass is controlled almost entirely by pre-emergent herbicide applied before germination. Dithiopyr (trade name Dimension) works slightly better on crabgrass specifically than prodiamine, though both are effective when applied on time. The pre-emergent creates a thin protective film on the soil surface — like wax on a car — that causes germinating radicles to curl in on themselves until the seed exhausts its stored resources. As long as the pre-emergent is down before March 15th and you do not break the film by aerating or heavily disturbing the soil surface after application, crabgrass simply does not emerge. On a well-maintained treatment plan with properly timed pre-emergent, crabgrass is a non-issue. It is one of the easiest summer annuals to prevent. The real lawn care challenges in Middle Tennessee are the perennial grassy weeds — dallisgrass, Johnson grass, and common Bermuda — that require multi-year selective treatment strategies rather than a single pre-emergent pass.

Smooth Crabgrass (Digitaria ischaemum) is a turf weed commonly found in lawns throughout Middle Tennessee, including Columbia, Thompson's Station, Spring Hill, and the surrounding areas. This entry is part of our Weed Identification Guide.

As lawn care and treatment specialists, we identify and treat Smooth Crabgrass regularly when servicing properties across the region. Proper identification is the first step toward selecting the right herbicide and timing for effective control.