The Victorian hotbed was a solution used to provide heated growing conditions for tender crops such as melons, cucumbers etc. just using the heat of rotting horse manure. Of course, they did it on the grand scale in the large walled gardens of their country houses. And they had an army of cheap gardeners to do the hard work!
See Cold Frames & Cloches in the allotment shop
Building Your Own Hotbed
We don’t have the same space or workforce for a Victorian hotbed but you can still create a small hotbed on an allotment or in a small garden following the instructions in this video presented by Simon Tetlow, deputy head gardener at the famous Tatton Park Gardens.
If you have a polytunnel then you could create a hotbed in there to really pump up the temperature.
By April or May when we still have frosts a hotbed is ideal for getting outdoor cucumbers, courgettes, squash and pumpkins off to a good start. Once the last frosts are passed, the cloche can come off and the plant will benefit from the high level of nutrients and water-retaining humus created by the manure.