"Jake D" wrote after
"Bob Hobden" wrote:

Plastic sheeting will have no benefit for such a short period and can
alter
the pH of the soil over an extended period anyway. Green manure I don't
use
as I've had a very bad experience with it.

Like what? Do you mind sharing?

When rotovated in it bound the clay together so well that I had to bank up
my spuds like dry stone walling. I'm sure I could have used the lumps and
made bricks.
Took a few years for the soil to get over it and I've never used a green
manure again. One chap on our allotment site does but then his soil is
totally different to mine, his is very friable, even slightly sandy.
My advise is if you garden on clay don't use it.

--
Regards
Bob Hobden