Recently I had to use Roundup in a very big area of my yard in order
to get rid of crabgrass (I needed to do it early enough before the
cold weather so I can seed the area now). I have read somewhere that
after killing the crabgrass is important to till the soil to get rid
of the roots. But some people have mentioned that if I aerate several
times that will be enough to prepare the soil for seeding tall fescue.
This is my first lawn and obviously my experience is limited. I will
appreciate any thoughts you may have. Thanks!
John, I don't know what zone your in, but in the Midwest our crabgrass roots
die in January so there is no need to dig them up. The real problem is that
the seed heads will distribute in Sept. and Oct. and that is what will cause
you the grief next spring. I know that Roundup does a good job killing the
plant but if the seed head has already been set, I doubt that the chemical
will sterilize the seed. Tilling the soil is good because it will bury the
seed deep into the ground where they are unlikely to reach soil level. Grass
seeds generally aren't viable if buried below 3/4". I prefer tilling rather
than aerating for preparation of soil. But handling a big rototiller is a
lot harder than it looks.
I agree with what John said. Before you till, put the appropriate
amounts of lime, fertilizer, etc on top so it is mixed in. In the
spring, put down a good lawy fertilizer, and preemergent weed control.
John Caldwell wrote:
I wouldn't recommend tilling the soil. This is a lot of extra work
for no benefit. Crabgrass is an annual plant. You've killed the
existing plants. Rent a slice seeder to establish the new grass.
Don't know what zone you're in, but for most parts, you need to do
this ASAP, as it's getting late and is past the prime window.
In the spring before temps get into the mid 70s, apply a pre-emergent
crabgrass control to the entire lawn which will prevent the problem
BTW, there are products that will selectively kill crabgrass without
killing desirable grasses. Unless the crabgrass had really killed the
desirable grass, this is a better approach. Also, this late in the
season, I would have just let the crabgrass die out on its own.
In the long term, tilling will always be the better way to go versus
aerating, slit seeding, or thatching. There is no comparison.
There is no reason to till the roots of crabgrass, especially after you have
After you spend all that time tilling to create a nice loose homogenous soil
mix, you should firm it back up by grading, pulverizing, leveling, and then
use a cultipacker or roller so that when you walk over you leave only a 1/4"
In the absence of soil test results apply 10-15 lbs of 10.10.10 and 50-75
lbs of dolomitic lime per 1000 sq ft.. Be sure to apply wheat straw at
about 2 bales per 1000 sq ft.. Water lightly but frequently for 10-14 days
then as needed. Followup in about 6 weeks with a high nitrogen turf grade
fertilizer at 1 lb actual N per 1000 sq ft.
If you till, you will have to rake out all the clumps of dead
grass and probably re-grade the yard. It's a LOT of work. If you
have anything other than a very small yard I would recommend
slit-seeding fescue now and then applying pre-emergent a in the
spring before the billons of crabgrass seeds can germinate.
If you can, it is well worth it to turn in a soil sample and wait 10
days for the results, check out <http://agronomy.agr.state.nc.us/ . I
turned in a soil sample last spring. We were ready to work a bunch of
lime into our soil, b/c our area is notorious for acidity. It is a good
thing we didn't put down lime, the soil sample came back and it turns
out our soil is alkaline! The service is free, and the division will
tell you how much and what nutrients your soil needs.
We have fescue germinating right now. My DH over seeded the bare spots
in our yard and I very carefully spread a 1/4 inch of top soil over most
of the spots (I ran out of soil and did not do this to a few spots) I
spread the top soil by hand to prevent the seeds from being pushed
around. It was tedious, but I think it really helped. The spots where
I did not spread top soil have not shown signs of germination. We
applied fertilizer while seeding.
John F wrote:
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