My lawn which is approx. 60x40 is made up out of probably 70-80% couch
grass, I think now that the previous tenant must have sowed it!
I thought about using weedkiller but there is such a lot I'm not sure if
this is the best option. I also thought about rotavating it but fear it
will make it worse.
Any suggestions or am I really limited?
A quick google shows that there is no selective herbicide for
this grass. That's true of many undesirable grasses. So, as
long as the soil is OK, I would wait until last week in Aug, then
kill of the whole lawn with glyphosate (roundup). Wait a week to
10 days and any spots that don't look dead, retreat. After another
week, mow it short, then rake up the debris. You should be able
to rent an over-seeder, which is a gas powered machine that cuts
grooves in the soil and drops seed. Re-seed it with a high quality
seed that is appropriate for the area. Apply starter fertilizer and
keep it constantly wet/damp for a couple weeks. Don't need to flood
it, just keep the top of the soil damp. That may require watering
several times a day for 15 mins, depending on the weather. Once the
grass is a couple inches high, you can back off on the watering.
Water it once a day, but for longer. Gradually taper off the watering
until after 6 weeks or so, you're watering every 3rd day, again that
also depends on the weather.
If you see any other undesirable grass, the trick is to either dig it
out or kill it before it spreads and gets out of control.
Make sure you use the right product. You want Roundup (glyphosate is
the generic). I'd use it at about 4%. Depending on the temps, etc
should be dead in 10 days or so. If necessary, hit any remaining spots
again. Mow it short, rake it up. You can reseed a week after applying it.
If you use some extended herbicide, then you could be screwed for 6