A root cellar is a structure which is designed to keep vegetables and some fruits at a stable, cool temperature which will prevent them from rotting or otherwise going bad. Root cellars were once a necessary fixture in any home where people wanted to be able to eat vegetables and fruits during the winter, and they are often present in older homes built through the early 20th century. In addition to being used to store fruit and vegetables, a root cellar can also be a useful place to store dairy products, grains, and a variety of other foodstuffs.
Root cellars take advantage of the earth as a natural source of insulation and coolness. A typical root cellar can either be dug as a pit independent of a house or another structure, or it may be built under a home, barn, or similar structure. Since deep holes are naturally cooler than the area around the surface of the earth, a root cellar will be cooler than the ambient air temperature by design, and several features can make a root cellar even colder.
Classically, a root cellar is installed in an area which is already cold, such as a north-facing hill in the Northern Hemisphere, and it may be shaded by trees and buildings. Thick insulation such as stone, brick, and straw may be used to keep a root cellar's temperature stable, while ventilation shafts pull cold air up, keeping a constant flow of cool air going through the root cellar.
Before the advent of refrigeration, the root cellar would have been the place to find everything from potatoes to bacon. Preserved foods like cured meats and pickled vegetables were often stored in the root cellar to ensure that their temperatures stayed stable during storage, while potatoes, turnips, carrots, cabbage, apples, and so forth were put into the root cellar as is and carefully packed to prevent sprouting or rotting.
Root cellars have also historically been used to age cheese, store dairy products, and so forth. On farms, root cellars ensured that people had steady access to a balanced diet throughout the year, even in areas where snow covered the ground during the winter, making farming impossible. The root cellar could also be used to store animal feed. In urban areas, people stored excess food in their root cellars so that they could eat well even during lean periods without paying stratospheric grocery bills for out of season foods.
Modern day root cellars continue to be used for the storage of fruits and vegetables, and a growing interest in natural preservation techniques and small scale farming in the early 21st century led to a revival of the root cellar in some communities. A well designed root cellar can entirely replace a refrigerator for the storage of food, saving a substantial amount of money in utility bills.