"Wanda" wrote in message
. ..
For about a year now I've been working on the sand trap that is my front
yard trying to get the grass to come back to life. Towards the end of
summer
there was finally a sign of life & the grass (cooch unfortunatey) started
to
grow. Since then the whole yard has also been infested with onion grass.
I've done a bit of research & it looks like the only way to get rid of the
stuff is to either pull it out or to remove all the grass, weeds & top
soil
& start from scratch. Because of the amount of lawn that's infested, &
because I was intending to rip up half the grass to put in garden beds
anyway, I've decided to go with the second option. My question is - how
much, in depth, has to be removed to ensure the weed's bulb is also
removed?


Have a dig around to get an idea of the depth they get. Depending on soil
types it's hard to guess, but depth wise I wouldn't expect any deeper than
20cm.
I can't remember if it was for nut grass, or onion grass, or both, but the
time to spray to kill is in August. Apparently it takes it into the bulbs
and kills them. I know at work we have over come a problem of onion grass by
repeated spraying, but that was in a garden situation, not lawn.
My guess is that if you did hit it with roundup in August, then again 4
weeks later, then get the couch going, then spot spray/paint on roundup for
any that comes through. After the couch takes over, and with normal mowing,
the onion grass shouldn't be a problem

Good luck