On Wed, 27 Sep 2006 10:13:47 -0400, cb wrote:
This is a multi-part message in MIME format.

------=_NextPart_000_0054_01C6E21D.9F06CDB0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

I'm in central Virginia, zone 7. I'm kind of new at the lawn thing. I =
planted my first lawn too late this past Spring, and it came in full and =
lush, but then got invaded by weeds and crabgrass, as I failed to put =
down preemergent. By now, half the lawn has turned into crabgrass and =

I'll bet it wasn't failure to use a pre-emergent herbicide, it was failure
to cut the lawn correctly, and probably failure to fertilize
correctly. You may also have a soil problem, possibly compaction or
pH. Your very best "weapon" in keeping down weeds is what
the weed science folks call "canopy closure"... getting the crop so
thickly growing that the weed seeds either don't germinate, or don't
grow.

If you've got clay soils and lots of foot traffic, you probably need
to aerate or till or work in more organic matter (my favorite lazy
method is to spread compost about 1/4" thick on the lawn, several
times a year.) If you've got very sandy soil, more organic matter
is also a good idea.


1) mow the crabgrass... don't let it reseed. Crabgrass is an annual,
so you don't need to hit it with herbicide now. You may or may not
want to use herbicides on your other weeds.

2) get a soil test --
http://www.ext.vt.edu/pubs/compost/452-129/452-129.html

3) fertilize and lime according to your test results

4) scratch up the soil surface and reseed with good quality grass seed
appropriate for your location, your soil type, and the amount of
sun the area gets. Bluegrass, for instance, likes sun. Fescues
tolerate shade better. Buffalograss likes hot and dry. If you
need to see green fairly instantly, once you've overseeded with
grass seed, overseed again with buckwheat. It's an annual that
won't survive your winters, and it'll add a little organic matter
to the soil next year. Buckwheat comes up fast (about a week)--
bluegrass takes 14-28 days to germinate, depending on temperature.

5) water religiously till the seedlings are pretty well established.
seed that's started to sprout and then dries out is dead seed.

6) consider whether or not you want to use another herbicide now,
and if so, what. Many cannot be used while you're getting grass
going. If you've got some truly nasty weeds like Canada thistle
or quackgrass, I'd probably given them a dose of glyphosate (Roundup
or similar), applied when the plants are actively growing. Most
herbicides work best when the plants are active, not at all if they're
just sitting there waiting for the right conditions to start growing
again. In the herbicide world, Timing is Everything. Stuff like
dandelions or knotweeds I'd forget about this season, or I'd
devote a few evenings after a frustrating day at work to pulling weeds.
Very useful therapy. g

7) Next year, mow properly. Sharpen the mower blades (torn, rather
than cut, grass blades are more prone to infection by various and sundry
fungi, and torn blades brown at the tip and look icky). Mow at the
correct height, and never remove more than about 1/3 of the grass
height at a time. 2-3" is about the right height for bluegrass,
fescues and perennial ryegrass (I feel strongly, however, that
3" is better for most lawn owners... the lawn is more weed-resistant).
You can mow a little shorter in the spring, a little longer in summer's
heat. But don't scalp the grass, and don't remove more than 1/3
at a cutting.

8) Fertilize and lime as soil tests indicate.

Kay