Is dethatching necessary every fall?
Written by
Tina Carter
Reviewed by
Prof. Charles Hartman, Ph.D.Dethatching is only needed if thatch layers exceed one-half of an inch, which you can picture as the thickness of a pencil. I like to use a soil probe on all my clients' lawns to check levels. One homeowner in Ohio removed one inch of thatch from their lawn due to drainage issues and after dethatching, the lawn's percolation improved by 50% in a few weeks.
Measurement Techniques
- Use a soil probe or garden trowel
- Measure thatch at 4-6 locations
- Spongy feel underfoot indicates excess
- Layer over 0.5 inches requires action
Regional Timing
- Zones 3-5: Dethatch by September 15
- Zones 6-8: Complete by October 15
- Southern zones: Avoid during dormancy
- Allow 6 weeks pre-frost for recovery
For best results, combine dethatching and overseeding. When dethatching and overseeding, dethatch the lawn first to help the seed make soil contact after overseeding. I had a Michigan client with 75% germination of ryegrass after dethatching first then overseeding. Application of starter fertilizer can help "kickstart" faster turf establishment after overseeding too; the starter fertilizer gets nutrients to the roots faster without thatch in the way.
Steer clear of typical complications: dethatching dormant grass, utilizing unsharpened blades, or forgetting your clean-up. I patched up a lawn in Nebraska that had dethatched late while the grass crowns were exposed to the frost. Always remove the dethatched debris, when you leave it in piles it can smother the grass and create an environment to grow snow mold.
Read the full article: 10 Expert Fall Lawn Care Strategies for a Lush Yard
