Garden Hotbed: How to Make One!
Colonial Williamsburg Garden Hotbed for Wintering Over Delicate Plants
A hotbed is a type of small greenhouse which uses the heat from composting of manures and other compostible materials to heat a small space in order to create a microclimate. This allows smart gardeners to “winter-over” delicate plants which would freeze and die, otherwise.
Here’s a simple depiction from a side-view: