Every year I put down pre-emergent's and when the barrier gets broken from
the lawn service I get crab grass. So I was thinking since there is no way
to stop the seeds from germinating that the only way to get rid of it
permanently is to let the seeds germinate, then kill it with roundup BEFORE
the grass matures enough to produce and drop seeds.
Does this sound like a good way to get rid of it permanently? I figure the
challenge I have is that when it grows I don't stop it from maturing and
I know I'll have brown spots until I seed and water at the end of the
When I said lawn service I meant the cutters. I have a service that
fertilizes, puts down pre-emergent's, etc. It's the cutters with the
weed-whackers around the edges that breaks the pre-emergent barrier and
allows the crab grass to grow.
I always have my lawn aerated in the fall.
A pre-emergent will stop the seeds that are there from germinating. Other
seeds may be coming into your lawn on the wheels of the mowing service.
Seeds that have not been exposed to pre-emergent will germinate. I do not
know what you mean that the cutters break the barrier of the pre-emergent.
Do not use Round Up as it will leave a major brown spot that will not fill
in readily. Bayer chemical does make a weed killer that also works on
growing crab grass without killing most lawns. It is the only selective
crab grass killer that I have seen. I have used it mid to late season, and
it will kill the crab grass. The problem is that it is a very slow kill.
It does not give quick results. It will cut the local seed infestation, but
crab grass seeds come from everywhere. A thick, healthy lawn will help to
prevent crab grass by choking it out. I think that your lawn service is not
doing a good job if the pre-emergent is not doing a better job for you.
What I was told about the pre-emergents is that it forms a barrier on
top of the seeds to prevent germination, and if this barrier is
broken,from any type of trauma to this "layer", like from the week
whackers, than the crab grass will germinate.
BTW, I was using Chem Lawn for years and this year I am using Scott's
lawn service, so we'll see what happens.
Crabgrass is hard to control and takes a bit of effort every year. In the
early Spring as others have noted, a pre-emergent treatment is required to
prevent the plants from sprouting. But later on, say in July, you need to
use a specific crabgrass control to kill plants before they can drop their
I tend to have some crabgrass that occurs depsite using a pre-emergent
too. And it's most prevalent at the strip of curb by the street.
It's an interesting theory that a weed whacker used to edge is the
cause. I tend to doubt it though. In my case, I use an actual edger
about every 6 weeks and still have a similar problem. I guess it's
possible that the edger also throws up some dirt that affects the
The conclusion I came to is that the small amount of crabgrass that
does germinate manages to do it mostly at the street curb because that
is where the grass tends to be the weakest. That area gets the most
sunlight and bakes right next to the hot pavement, so the grass never
does as well as in the center of the lawn. It could also be that I
should put down the pre-emergent earlier, as that area may be getting
to germination temps well before the rest of the lawn.
I use Acclaim to spot treat the crabgrass. If you hit it early, it's
very effective, far better than any of the crap ones I've bought at
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