"Michael Bell" wrote ...
My niece lives on a farm in the Vale of York, rather sandy soil. It is
an organic farm. One of the problems is couch grass growing under the
edges of the polytunnel. The stolons grow about 4" deep and they grow
an astonishingly long way. It causes a LOT of work to get rid of it.

Others must have similar problems and have found answers. What are the
answers?

Get some Dampcourse rubber/plastic stuff as used by builders, comes in a
roll and is about 11 inches wide, Dig this down vertically all around the
tunnel and it will be a barrier to shallow rooted weeds. You can push a
spade down all around to make a slit trench. Used it myself to protect my
garden from the Ground Elder taking over next door.

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Regards
Bob Hobden
W.of London. UK