GardenBanter.co.uk - View Single Post - non-fertilizing pre-emergent

Steveo · 08-08-2007, 11:24 AM posted to alt.home.lawn.garden

wrote:
Steveo said:

wrote:
Chas Hurst said:

"Eggs Zachtly" wrote in message
...

It needs to be put down /before/ the weed seeds germinate. That's
early in the Spring, in your neck o' the woods.

I did this last spring. The results were disappointing.

If it was the first time you've applied it, you won't get a 100%
stoppage of the weeds. You won't even be close. You also may have put
it down late, after the seeds had already germinated. "Spring" is a
pretty big window.

There are literally millions of weed/grass seeds in your soil. As each
one germinates, it pokes a tiny hole in the pre-emergent barrier.
Eventually, an undesireable will get through. Keep applying the
pre-emergent at the proper time, at the proper rate, and in a few
years you'll notice a marked decrease in the undesireables.

I have read that some undesirable grasses germinate in the late
summer. Are you claiming this is not so?

Annuals will set seed any chance you give them. But, winter will kill
them off. Putting down a pre-emergent in mid summer will do you *no*
good.

Certain annual grasses are about to germinate again as summer ends.

"grasses" (Ok, I'll give ya that if it's an unwanted grass, it can be
classified as a weed =P )

Yes, those pesky grass weeds.

Now is the approximate time to apply pre-emergent aiming at poa annua
suppression here in N Ohio, timing is everything. It will do *some*
good if applied at the proper time. I've used dimension with some
success.

It's a bit hot, don't you think? I'm only a couple states over from you,
and we're in triple digits. Poa's not a problem, and won't be for a
couple months months. It's early, IMO.

As I said timing is everything and that will definitely vary by location. I
usually apply it in about two weeks here.

Dimension works well for crabgrass, even on seedlings. Does it do the
same for young poa plants (or, only as a pre-emergent)?

I don't know if it has any post emergent value on poa, I'm always sure to
apply it before it germinates. The only caveat with that is possible root
pruning of desirable turf, and I keep it off bentgrass as much as possible.