I am trying growing in soil blocks this year- that is compressed blocks of compost with the seed popped in the top. If the blocks are kept moist, they should hold together long enough for the roots to bind the compost together. The benefit of growing this way is that the roots are air-trimmed rather than getting pot bound. Anyway, I've found keeping the blocks on top of capillary matting a good way to keep them moist, but the roots are starting to grow into the matting. Is it possible to buy matting that the roots can't penetrate?
See capillary matting - below.
I believe Agralan supply matting with a "cover".
http://www.agralan.co.uk/acatalog/AMATURE_GARDENER.html
I have ordered some but it has not arrived as yet.
Jerry
many thanks -will order some of that.
Or, as suggested, if you have the matting & can't get the 'cover' separately, try weed suppressant?