The current watchwords for trends in Western cooking are fresh and local. The chef's ideal is to use ingredients harvested as close as possible to the site where they will be transformed into a meal. While modern greenhouse-farming techniques have certainly extended the growing season of many vegetables, finding and cooking fresh, local produce in the winter months can be a challenge.
In the temperate zone — that includes North America, Europe and most of Japan — where seasons come and go, traditional methods for preserving and extending food life have been employed for centuries. Ironically, when modern preserving techniques — specifically canning and freezing — were developed in the West and spread across the globe, some of the old ways of food preservation fell out of practice in these areas and were lost to all but a few.
One of the easiest preservation methods practiced in the temperate world is underground cold storage. Root cellars are called such because they are used to hold large inventories of "storage" vegetables. Produce most suited to prolonged preservation includes those vegetables grown underground — onions, potatoes and other root-vegetable varieties — as well as most grains.