Hi Everyone,
I moved into a new build last summer in southern New Hampshire. Last summer I was infested with weeds (mostly crab grass) but I had some success with aerating and over-seeding in the fall. This spring I’d like to spread a pre-emergent like prodiamine.
Throughout the fall we saw all of our weeds die out. I had mentioned to family members that I felt I may need a dethatcher to clean up all the dead weeds but I’ve had some people tell me the lawn is too new to need that done. What do people think here? I’m convinced we need to clean it up in order to give the pre-emergent the best chance to do its job.
Thank you!
by McComark
9 Comments
Dethatching is a recent trend in lawn care that’s become more common thanks to youtube creators and other non-academic sources. As such, there’s a widespread misunderstanding/misinformation about the topic. This automatic comment has been created in the hopes of correcting some of those falsehoods.
Thatch is the layer of stems and roots, both living and dead, that makes up the top layer of soil. Grass clippings are not thatch and do not contribute to thatch. The thickness of thatch can only be assessed by digging into the soil.
Some thatch is good. While some academic sources say that under 1 inch of thatch is beneficial, most settle for half an inch. Thatch is beneficial for many reasons (weed prevention, traffic tolerance, insulation against high temps and moisture loss, etc) and should not be removed. Over half an inch of thatch may not warrant removal, but the underlying causes should be addressed. An inch or more of thatch SHOULD be addressed. Dethatching as a regular maintenance task, and not to address an actual thatch problem, is NOT beneficial… Again, some thatch is good.
Thatch problems are not typical. Excessive thatch is a symptom of other issues, such as: over-fertilization, overwatering, regular use of fungicides, excessive use of certain insecticides, high/low pH, and the presence of certain grasses (particularly weedy grasses).
Dethatching with a flexible tine dethatcher (like a sunjoe) causes considerable short-term and long-term injury to lawns, and is known to encourage the spread of some grassy weeds like bentgrass, poa annua, poa trivialis, bermuda, nimblewill etc. In some RARE cases, that level of destruction may be warranted… But it must be done with great care and attention.
A far less damaging alternative to dealing with excessive thatch is core aeration. Core aeration doesn’t remove a significant amount of thatch, and therefore doesn’t remove a significant amount of healthy grass. BUT it can greatly speed up the natural decomposition of thatch.
Verticutters and scarifiers are also less damaging than flexible tine dethatchers.
For the purposes of overseeding, some less destructive alternatives would be slit seeding, scarifying, manual raking, or a tool like a Garden Weasel. Be sure to check out the seeding guide [here.](https://www.reddit.com/r/lawncare/s/pUsKCxyvwQ)
Additionally, be sure to check the list of causes above to be sure you aren’t guilty of those.
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No, don’t dethatch.
No. It needs to just be raked out. You have snow mold fungus. That’s the white-ish tint in some areas.
Same for me down in MA…hell I still have snow piles in my front yard..lol
It doesn’t need to be raked hard, just drag a tined rake with moderate pressure behind you as you walk…do a few passes in different directions. Or if you only have a few areas that is al matted up, then do that locally. Breaking it up will kill off the fungus, and allow for better air movement.
I see you use a Scott’s spreader
If you have a mower with a bag attachment this looks like you could go over it with that and get most of it up. As others have said, maybe give it a raking and then mow once or twice and you should be good to go
Aeration would probably be more helpful (usually always is)
I’m raking before putting pre-emergent down. Taking my sweet ass time too because I don’t like it.
Likely rip out way too much dethatching, I made that mistake once. Still too early to do anything. My lawn looks like yours, but my snow has all melted, I will likely core aerate once we are past freezing nights, in a month or so.
I would scarify or verticut personally as it’s less aggressive on the lawn, but will do wonders for cleaning up the thatch, leftover dead weeds, etc. You will still need to take up the mess left behind, or run over it with a rotary mower with a bag attached.