Hot Box



Terracotta Finish

A HOT BOX is a concept idea rather than a practical way to generate and use the heat given off by decaying organic matter in a typical garden setting. The idea is to use the heat produced by the composting matter to create a heated propagator in late winter/ early spring. If you have access to the raw materials, it will not cost you anything and with sufficient time and effort, and more importantly volume of materials should work.  The general concept was used by the Victorians to raise the air temperature under glass. The aim is to start seedlings and plants off earlier in the season than normal and when the heat has finished the contents of the compost bin can be dug into the soil to feed the new plants!

To make the Hot Box the traditional method has been to thoroughly mix together equal parts of fresh horse manure and deciduous leaves, turning the heap three or four times during the course of a fortnight. The leaves help to moderated the heat and release it over a longer period. After two weeks fork the mix into the Compost Bin. Firm it down and position the removeable glass frame on top. Then let the temperature build up for a day or so, level the surface and cover with a layer of soil 6″ – 8″ (0.15m – 0/2m) deep. Do not plant or sow into the soil because the powerful mix could damage young roots. Instead, put the seed trays or plant pots up to their rims in the warm soil. Do not allow the temperature inside to exceed 70F (21C). . Afterwards, plant ridge cucumbers, marrows or melons directly into the soil – plants which enjoy the rich manured ground or fork the contents into the garden soil digging it in.

Click here to see the temperature results for different materials that we tried composting.