How To Dethatch a Lawn
When a thatch layer is more than 1.5 cm thick, it’s time to dethatch. You have three options.
When a thatch layer is more than 1.5 cm thick, it’s time to dethatch. You have three options: remove thatch manually, rent equipment or hire a professional lawn care service.
For small lawns or thatch less than 3 cm thick, consider removing thatch with a rake. Manually dethatching causes the least amount of stress to a lawn. A rake with hard tines may or may not work effectively to pull thatch to the soil surface.
A specialized dethatching rake has sharpened tines designed to lift thatch away from soil. With a dethatching rake, use the same motion as with a traditional rake, allowing tines to dig into thatch and pulling it upward to loosen and lift thatch. Done correctly, you should feel the thatch separating from soil and see it being lifted to the lawn surface.
A dethatcher is also known as a vertical cutter, verticutter or power rake. This machine has vertical blades or rigid wire tines that slice into thatch and lift it to the lawn surface.
When using a dethatcher, blades must be set to a specific spacing based on grass type. Typically the rental facility will do this, but be sure to ask. Cutting depth is also adjustable. Usually you want blades to cut no deeper than 1.5 cm into soil, if at all. The rental agency should be able to advise you.
A dethatcher is a large, heavy machine that requires some muscle to maneuver. You’ll need a truck to transport it and more than one person to load and unload it.
Hire a Professional
If you’re uncertain about using a dethatcher, consider hiring a lawn service company to do this task. Trim costs by having them only perform the dethatching, while you tackle the follow-up tasks.
- Mow grass to half its normal height before dethatching. This allows you to see the thatch layer more clearly and observe your progress as you dethatch.
- Flag irrigation heads or other hidden objects in the lawn to avoid damaging them.
- For best results, always dethatch in at least two directions at 90° angles to one another.
Alternatives to Dethatching
If your lawn has mild thatch, a plug aerator may be effective. The aerator dethatches the lawn in each spot where plugs are removed, while avoiding the creation of bare spots that a dethatcher causes. Regular aerating can help prevent thatch build-up.
What To Do After Dethatching
Expect your lawn to look somewhat ragged after dethatching. Follow these steps to groom a healthy lawn – a process that should take three to four weeks.
- Rake and remove the thatch scattered over grass. Compost or use it as mulch – but only if you haven’t applied a weed-and-feed product in the four weeks prior to dethatching.
- If dethatching created bare spots, reseed. After applying seed, rake it into soil. Add a light covering of organic matter, soil, or sand.
- Fertilize after dethatching. If dethatching occurs around the time of your lawn’s regular seasonal fertilizing, delay fertilizing until after dethatching.
- Keep recently dethatched lawns well watered to ensure grass recovers. Watering is especially important if you reseed.
- For warm-season grasses, which are dethatched in spring, apply a pre-emergent herbicide after dethatching to keep crabgrass seeds from germinating. If you plan to overseed in fall, apply the pre-emergent herbicide 75 to 90 days before overseeding.
Prevent Future Thatch
Proper watering, fertilizing, mowing and regular aeration help prevent thatch build-up. Follow proper techniques in these areas, and you’ll only have to dethatch as needed, not as a regular lawn chore.