Kitchen Garden Forum

I would think you could use any thick cotton material, such as old cut up sheets or curtains, or strips of very old towelling. The key thing is to allow surplus moisture to drain through but to stop the earth being washed away. it will probably have to be replaced annually though as if its cotton based it will eventually decompose. I suppose one could even use strong plastic bags as trough liners providing you pierce tiny holes in them to let surplus moisture drain away.

Looks like standard weed suppressing fabric to me.