I use Aldi capilliary matting and a couple of buckets on the 6'x3' hot bed I have (frame made of old decking, layer of polystyrene in the bottom, 40' soil warming cable, 2" of sand, layer of punctured polythene, matting, plants in modules) and it's been very successful, WABOL it will be getting som elighting (LED) on it too this year, I want a crack at a massive onion...