Wanda wrote:

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?

Dig around, carefully following the onion grass down till you get to the
bulbs, see how deep they are. In clay, I can follow them 30+ cms then
lose them, but it might be less in sand.

Jane