I'm in Minnesota, which I believe is Zone 4 for the most part. Like a lot of
people, crabgrass is a part of my lawn. Overall the lawn looks pretty good,
but the crabgrass is encroaching.
Is there any way to poison or kill the crabgrass at this time of year? Or
did I miss my chance in the spring?
There's too much to spray with one of those Windex-type bottles of Ortho or
something, so is there some kind of broadcast spray that will only kill
I had the same problem last year. I went to several garden shops to
find if there was anything I could do. The best advice is that there
really is little that you can do. I ripped up chunks of my lawn and re
planted with seeds. There seems to be little else for simple answers.
However I can say that in the spring I did put down pre emergent seed
killer and it really worked well. I was surprised at how little came
back. So you may have to be patient and wait. On the plus side I bought
my pre emergent killer in the middle of the summer when it was about
half the price, as the garden centers where trying to get rid of it. I
held on to in till the following spring. I think that one of the things
that causes the crab grass to take over is the dry times in the summer
when I foolshly listened to the city and seldom watered. This gave the
crab grass on oportunity. I will not make that mistake this year. I
think a healty lawn keeps it at bay.
iiiiiiiiiiiiii < - picture of my grass.
Sterilize the lawn. Wait for the herbicide to dissapate. Plant with some
other type of grass. Keep well watered during hot dry weather. :-P
I lived in Las Vegas for 15 years. Healthy fescue or rye or other grasses
will keep the crab grass and bermuda out, but once it's established, you are
pretty much stuck with it. In the winter it will die out, and you can plant
a winter rye type of grass and keep it well watered. Not sure if that will
stop the crabgrass from coming back or not.
Matthew Reed wrote:> I lived in Las Vegas for 15 years. Healthy fescue
or rye or other grasses
It won't in north Texas.... I had a nice rye lawn thru the winter,
waiting for it to die off this spring and the Bermuda to re-establish.
Great globs of crabgrass came in before the Bermuda.... Bummer....
Next year I will try the pre-emergent .
southern part is zone 4- northern part is zone 3
Like a lot of
crabgrass poisons the soil under it and kills other grasses - you either
remove any crabgrass that gets by your treatment this year or repair dead
patches by replacing some poisoned soil next year..
There are several approaches to crabgrass control
1) Stop it from starting:
Cheapest and most effective - pre-emergent. It is very effective on
crabgrass when applied around mid-may in Minnesota.
An application now will mitigate further damage, but it won't kill what
has already sprouted, which is over half the crabgrass.
A caution - a) pre-emergent and crabgrass pre-emergent are the same stuff,
used for the same purpose for different weeds, b) the stuff decays, and c)
crabgrass needs a good dose to keep it dormant.
Pre-emergent only lasts (protects) 6-12 weeks before it breaks down,
depending on how heavy you put it down. So you have say 10 weeks from when
you put it down.
Crabgrass requires 3 days of soil temp around 70-80 degrees to
germinate - usually mid-may in mid-southern Minnesota.
Pre-emergent is now being sold as a general weed preventative, which it is
if you put it down early, like in April in southern Minnesota - BUT IF YOU
WANT it to only be a crabgrass preemergent that lasts most of the season,
then you need to get it down later.
Timing goes like this - put it down in April, and it is pretty much gone
in 3 months - that means crabgrass will sprout in late July and August, if
you don't re-apply in late June.
But put it down in mid may, and the late august nights are too cool for
the stuff to sprout and get a foothold.
2) Kill the young:
- Once crabgrass starts, get the young stuff with methanearsenate [sp].
It's a little pricey, but crabgrass will spread and posion the grass, and
the stuff works. You may need a second application to get all the
The stuff is usually labelled crabgrass killer. Ortho makes one, as do
3) mechanical removal - Use a crabgrass rake to lift the tendrils (or lift
them by hand), and then pull out the crabgrass by hand, one plant at a time.
There is an Ortho Crabgrass killer spray, but my personal experience
was that it was not too effective. Hand pull the crabgrass out and
don't let it re-seed. Most importantly, overseed your lawn in late
summer. Crabgrass likes a sunny sparse lawn, and won't grow in a
thick lawn. A thicker lawn will greatly cut down on many weeds. You
may need to use pre-emergence next spring and again 90 days later.
I haven't had very good luck with that Ortho Crabgrass killer spray
either. I will say that last year I had Crabgrass worse than I have
this year. Last Summer, I pulled it all out, and then sprayed any
little sprouts that would come up after that.
I put a pre-emergent on the lawn this April. . .I have much less of it
Why bother? It's an annual. Save your money and give the lawn a good
refurbishing this fall -- overseeding, fertilizer, lime, the whole ball of
wax. In the meantime, get your lawn mower blade sharpened (especially if
the ends of the grass you've cut look chewed, and a soil analysis.
Also, this is an old crabgrass faq I wrote a few years ago. Try it.
Easy once you understand the biology of crabgrass, _Digitaria sanguinalis
or D. ischaemum_, annual species that germinate in bare soil in cool
temperatures, then doesn't grow much until the heat of summer comes. It
is intolerant of shade.
1) Fertilize and lime your lawn in spring and early fall, to help thicken
it. Best to get a soil analysis from your local master gardeners or
extension service, but you can probably wing it a bit with the help of
someone who knows the soils in your neighborhood well. If the grass forms
a nice, thick mat, it doesn't allow weed seeds to germinate. (Lime helps
correct the soil pH to 5.5 to 6.5, which allows the other grass plants to
take up nutrients easily.)
2) Obtain a wooden stake and put it in the ground someplace where you can
see it easily. If you've got the standard bluegrass/fescue lawn of most
of the northern states, make a mark at 3.5" and 4" from soil level. Set
your lawnmower blade to 2.75-3". When the grass hits the 3.5" stake mark
you should mow. At 4", you *must* mow. No cheating. If you remove more
than 1/4 to 1/3 the length of a grass plant in a single mowing, it weakens
the plant, possibly opening the soil for weed seed germination. Because
the grass stays comparatively long, it also shades the crabgrass seedlings
that have germinated and keeps them from developing.
Some times of the year, you'll mow a couple of times a week. Some times
(typically when it's hot), you won't mow for weeks.
The original research on this method of crabgrass control was done back in
the 40's or 50's -- the fertilizer used was chicken manure, and the
reported success was something like 80% reduction in crabgrass in the
first year, and 95% in three years. I tried it myself in a badly abused
lawn in a house I moved into... formerly a feedlot, more than 40 species
of weeds in the lawn. I used 10-10-10 fertilizer, the cheapest I could
find, a little glyphosate (roundup) on thistles and quackgrass (a
rhizomatous perennial) and some good quality bluegrass and fescue seed as
an overseeding in the fall.
I had virtually NO crabgrass in the lawn the following year, and, in
contrast to the neighbors who kept scalping their lawns "to avoid mowing",
I was down to 3 species of weeds within 5 years -- without major pain,
strain or suffering. The time I spent in the cooler months mowing was
certainly no greater than the time and effort the neighbors spent hauling
pesticides, spraying, cussing, digging, etc. And I was collecting
specimens for the weeds class I was helping with from their lawns, not
mine, because I had so few weeds, and so few species of weeds.
The lawn quickly reverted to a weedy mess after I moved out and the new
owners went back to scalping the lawn, opening up all sorts of bare soil
for weeds to flourish in .
Kay Lancaster firstname.lastname@example.org
I did try your advice a few years ago when we got a new home with a lawn
that was 100% crabgrass thanks to improper seeding.
It works. Thanks!
Hand weeding when crabgrass is still small helps greatly too if some
Apply a preemergent product in spring when the forsythia are in full bloom, and that should take care of the bulk of the new (annual) crabgrass plants.
Suzy O, Zone 5, SE Wisconsin
face=Arial size=2>...</FONT></DIV><FONT face=Arial size=2>> I'm in Minnesota,
which I believe is Zone 4 for the most part. Like a lot of <BR>> people,
crabgrass is a part of my lawn. Overall the lawn looks pretty good, <BR>> but
the crabgrass is encroaching.<BR>> <BR>> Is there any way to poison or
kill the crabgrass at this time of year? Or <BR>> did I miss my chance in the
spring?<BR>> <BR>> There's too much to spray with one of those Windex-type
bottles of Ortho or <BR>> something, so is there some kind of broadcast spray
that will only kill <BR>> crabgrass?<BR>> <BR>> Thanks!<BR>>
<BR>> -- <BR>> Dave <BR>> <BR>></FONT></BODY></HTML>
I've heard about the forsythia and crabgrass. But, unfortunately I've
seen forsythia in full bloom in mid-January. I have also heard about
looking for the first spring dandelion bloom. I apply pre-emergence
the first week of March. The timing of application is very important
and varies by location. I am in E. TN.
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