Dave Gower wrote:

...You
can put down a sheet of black plastic, and after 10 days or so when the
grass has died simply cut slits where you want to plant the veggies. Then
remove the plastic when the seeds start to sprout while they're still tiny
enough not to catch on the plastic. The sod rots away and acts as mulch for
the new plants.



It takes more than 10 days to kill the sod. I put black plastic down
over grass for a temporary greenhouse once and it was spongy to walk on
for about a month and a half. Moreover, the growing point is underground
for grass, so it takes more effort to kill it. You might get rid of the
leaves, but once you take off the plastic, the grass will recover (maybe
not to the lush-lawn standard, but certainly to the garden-weed
standard).

Why not leave the plastic on the garden when you plant. You can cut
holes for the plants and leave the rest to block the weeds. This works
great for transplants. You might want to put some stones or bricks on
the plastic adjacent to the holes so the plastic doesn't shift when the
wind blows and abrade the plant stems. If you're direct seeding, the
stones will keep the plastic from shifting to cover the seeds you want
to grow.