A new growing season commences, and with it comes the annual ritual of building the hot bed for propagating our spring seedlings, and heating the greenhouse. If you are not familiar with hot beds, they are basically a mass of undecomposed material which during decomposition creates rather a lot of energy some of which is expelled in the form of heat. We create a structure to hold the compost (5 pallets fixed together) in the form of a cube approx 1.2 m square, which we layer with fresh horse manure, and straw.
After a while the pile begins to decompose and heats up to around 60ºC. We then sow our spring seeds into seed trays and modules and place on top to germinate.
This year we have made our hot bed into a Johnson Su Bioreactor, a hot bed with air channels running through it to speed up decomposition and increase the heat produced, we will keep you posted on how hot we can get up to! The only difference between our usual hot bed and our version of the Johnson Su bioreactor is that we arranged 5 fence posts equally spaced in the hot bed and filled around them packing the material down and watering as we filled, trying to keep the posts upright.
When full we simply wiggled the posts around and pulled them out leaving air channels running all the way down to the bottom.
We shall see what results we get with our seedlings and with the type of compost produced by the bioreactor, sometimes when compost gets too hot it can reduce the amount of nutrients in it so hopefully ours will be like Goldilocks porridge, not too hot, not too cold, just right!