Pre-emergent apps. / aeration


LawnSite Bronze Member
I have a question for the guys that do spring aeration and also use a pre-emergent crabgrass control, any pre-emergent for that matter. Do you think that applying pre-emergent crabgrass control in the spring, immediately after an aeration will redice its effectiveness? I have done a search with no luck so if someone can point me towards the right thread I would appreciate it. I have seen the thread by some university that said that only dethatching, not aeration disturbes the exhisting chemical barrier.


LawnSite Senior Member
I personally dont think you need to aerate in the spring. Of course in my area we use Turf type tall fescue. I can't speak for what the guys are doing in other zones.

We do all the aeration and seeding in the fall. In the spring, I focus more on getting out my Pre-emergents and post emergents.

Aeration is great for the roots, but you are also pulling weed seeds from the ground and bringing them to the surface. I'm trying to get ride of the weeds I got and prevent weeds from coming, so thats my reason for not aerating in the spring

As to your question I dont think applying the pre-m after you aerate would be a problem. However I wouldnt aerate after you have done the pre-m.

hope that helped


LawnSite Bronze Member
New Hampshire
Here is my take on this subject. Pre-emergents create a thin chemical layer that technically does not inhibit germination of the crabgrass. The crabgrass seeds do germinate but the outer layer of cells are destroyed when they pass through the barrier and thus the crabgrass seedling dies as its root desiccates.

The preemergent barrier is about .25 inches deep. When you aerate you puncture the barrier and that is why if you aerate too late in the season you will get a bloom of crabgrass. Aerating early the soil will close in the plug and the barrier will be restored. pull all the plugs and weed seeds you want, when the root hairs reach the barrier they will be damaged.

My suggestion is to schedule you aeration either between your two spring pre-emergent control applications or in the fall.:blob1:

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