When to Dethatch, State by State

Rake out the spongy layer — only when it exceeds ~½ inch. The right week depends on where you live — every window below comes from that state's own climate record.

Cool-season lawns: why then

Dethatch cool-season lawns in early fall (or early spring as a second choice), when recovery is fastest — the same logic as aeration, and the two jobs are often done together. First check that you actually have a thatch problem: under ½″ of thatch is normal and beneficial; tearing up a healthy lawn does more harm than the thatch.

Warm-season lawns: why then

Dethatch warm-season lawns in late spring through early summer, once fully green and growing hard. Zoysia and Bermuda are the heavy thatch producers; St. Augustine is better verticut lightly or topdressed. Never dethatch near dormancy in either direction — the lawn can’t rebuild before stress arrives.

StateRegionCool-seasonWarm-season
Alabama Warm-season — Mar 21 – May 19
Alaska Cool-season Jul 5 – Sep 10 —
Arizona Transition zone Nov 1 – Nov 5 Feb 2 – Jul 30
Arkansas Transition zone Aug 29 – Sep 29 Apr 18 – May 30
California Transition zone Oct 12 – Nov 8 Feb 9 – Apr 7
Colorado Cool-season Aug 6 – Sep 11 —
Connecticut Cool-season Aug 24 – Sep 15 —
Delaware Transition zone Sep 2 – Sep 23 May 2 – Jun 2
District of Columbia Transition zone Aug 30 – Sep 20 May 3 – May 31
Florida Warm-season — Feb 14 – Apr 7
Georgia Warm-season — Mar 30 – May 19
Hawaii Warm-season — Mar 10 – Apr 7
Idaho Cool-season Jul 30 – Sep 9 —
Illinois Cool-season Aug 15 – Sep 24 —
Indiana Cool-season Aug 19 – Sep 29 —
Iowa Cool-season Aug 5 – Sep 8 —
Kansas Transition zone Aug 20 – Sep 17 May 9 – Jun 11
Kentucky Transition zone Aug 26 – Sep 28 Apr 28 – Jun 8
Louisiana Warm-season — Mar 1 – Apr 25
Maine Cool-season Jul 30 – Sep 3 —
Maryland Transition zone Aug 22 – Oct 10 Apr 20 – Jun 10
Massachusetts Cool-season Aug 6 – Sep 28 —
Michigan Cool-season Aug 8 – Sep 19 —
Minnesota Cool-season Aug 4 – Sep 4 —
Mississippi Warm-season — Mar 18 – May 16
Missouri Transition zone Aug 25 – Sep 23 Apr 29 – May 30
Montana Cool-season Jul 30 – Aug 20 —
Nebraska Cool-season Aug 1 – Sep 9 —
Nevada Transition zone Jul 17 – Oct 29 Feb 21 – Jul 24
New Hampshire Cool-season Aug 1 – Aug 30 —
New Jersey Cool-season Aug 26 – Oct 10 —
New Mexico Transition zone Aug 4 – Oct 2 Apr 9 – Jul 9
New York Cool-season Aug 13 – Oct 9 —
North Carolina Transition zone Aug 29 – Sep 27 Apr 25 – Jun 1
North Dakota Cool-season Jul 29 – Aug 19 —
Ohio Cool-season Aug 22 – Oct 1 —
Oklahoma Transition zone Aug 31 – Sep 23 Apr 28 – May 30
Oregon Cool-season Jul 19 – Oct 20 —
Pennsylvania Cool-season Aug 21 – Oct 6 —
Rhode Island Cool-season Aug 28 – Sep 18 —
South Carolina Warm-season — Mar 4 – May 23
South Dakota Cool-season Aug 4 – Aug 27 —
Tennessee Transition zone Aug 26 – Oct 5 Apr 13 – Jun 6
Texas Warm-season — Mar 2 – May 19
Utah Cool-season Jul 31 – Sep 29 —
Vermont Cool-season Aug 7 – Sep 3 —
Virginia Transition zone Aug 30 – Oct 1 Apr 26 – May 29
Washington Cool-season Aug 2 – Oct 6 —
West Virginia Transition zone Aug 21 – Sep 14 May 14 – Jun 21
Wisconsin Cool-season Aug 7 – Sep 10 —
Wyoming Cool-season Jun 29 – Aug 20 —

Ranges span each state's featured cities — click your state for city-level windows, or jump straight to your ZIP with the lawn calendar lookup.

Other timing questions

🌾 Overseed⛳ Aerate🛡️ Apply Pre-Emergent🧪 Fertilize🍂 Stop Mowing❄️ Winterize