Having read Charles piece on his Hot bed in his green house, I decided to have a go
myself in a smaller way, to see if it could help warm some seed trays, and also raise the temperature of my greenhouse. I used a small box, approx. 3ft 6 x 3f, lined it with plastic and added fresh manure and bedding from my horses stable, topped off with a few inches of hay. Initially not much happened, I added some extra water a week in, and within days things started to heat up. I’ve a max/min thermometer both inside a propagator on the hot bed, and one on staging next to the hot bed, minimum temperatures last night where 4 degrees on the staging, and 8 degrees in the propagator on the hot bed, really impressed with the results. The smell of the warm hay when you open the greenhouse is really pleasant too. Any one else had a go?