Crabgrass preventer timing in seven states
Spring preemergent windows from Virginia, North Carolina, Georgia, Texas, Pennsylvania, Ohio and South Carolina extension pages, with each one's cautions.
By LawnYear editorial team · Published · Updated Windows are read from the extension publications listed under Sources; the dates are approximate.
Approximate dates for your state. Check with your local cooperative extension office before you act.
A preemergent herbicide has to be down before crabgrass germinates, so the sources all give a late-winter or early-spring window, each in its own way. This site gives no product advice; read the label and ask your extension office.
In the South, the window opens first. Clemson puts preemergent herbicide in mid-February for coastal and central South Carolina and mid-March for the piedmont and mountains. The University of Georgia rates February and March best for preemergent on bermudagrass and the other lawn grasses it covers, with April possible. NC State says early March, sooner in the Piedmont and coastal regions, for a tall fescue lawn, and mid-February to early March for bermudagrass. Texas A&M AgriLife says crabgrass germinates around mid-February in South Texas, early March in North and Central Texas and mid-March in the Panhandle, and to apply before that; for St. Augustinegrass it keys the spring application to soil at about 55 F for 4 to 5 consecutive days.
Further north, the windows run later. Virginia's chart marks March to April. Penn State gives three windows by area: March 15 to April 15 in southeastern Pennsylvania, April 1 to May 1 in other areas and April 15 to May 15 in the northern tier and high-altitude counties. Ohio State's northeastern Ohio calendar says to apply in the first weeks of April, with April 25 as the deadline.
Two sources tie the herbicide to your seeding plans. Virginia says to skip the preemergent where you plan to seed. Georgia says not to apply preemergence on a tall fescue lawn that is to be seeded or sodded within 3 to 4 months. Texas adds that the fall preemergent for bermudagrass should be skipped if you plan to overseed with ryegrass.
Virginia and Texas also list a fall application aimed at winter weeds such as annual bluegrass, henbit and chickweed, and Clemson lists a September application. Clemson's St. Augustinegrass program adds a second spring application 8 to 10 weeks after the first.
This site has no preemergent timing for Missouri, because the University of Missouri article it uses covers seeding and fertilizing.
How we read the sources: where a post sets states or grasses side by side, the comparison is ours, made by reading the extension pages next to each other. Every number comes from the page named.