Root Cellars for Food Storage
Root cellars are a very old-fashioned way of preserving food, and it can be one of the simplest if you have the right location for it. All a root cellar is is a cold, dark location that also has the right level of humidity to allow some types of fruit and vegetables to last months without any processing at all.
Pros and Cons to Using a Root Cellar
The biggest positive aspect of using a root cellar is the simplicity. Once you have the right location and conditions set up, you just store your produce in baskets or buckets and leave as-is in the cellar until you are ready to use them.
The problems come from trying to get the right conditions for what you are going to store and that this method will only extend the life of your food for a few months or possibly to a full year if you are lucky. That's fine for standard food preservation from one season to the next but it usually isn't the right type of time frame that you need for a good emergency food storage system.
There are also limits one what kind of food will store this way. Most root vegetables (potatoes, turnips, beets) and apples are well-known for great root cellar storage.
The specifics of where or how you build a root cellar are less important that you are able to achieve the right environment once it's in use. Not all vegetables will store best under the same conditions but you should have a space that stays between 32 and 38F (0 and 3C) without dipping below freezing. Humidity should also be very high, around 90%. The temperature is much easier to maintain naturally during the winter months, which is why this method works so well as a yearly method to save fresh produce until the next season. Once you are storing through the summer, most underground places will be too warm.
You also need to allow for ventilation. Gases can build up that will hasten the ripening (and degradation) of your food so you have to have some sort of venting to the outside for fresh air. Because air should be moving, you will have to have a source of moisture present to keep the humidity level up. A room that has a dirt floor will usually be damp enough but if you do not have that source for moisture, then you can keep a few buckets of wet sand among your stores. Just add more water to it as the sand dries out. Keeping a hygrometer in the room to measure humidity is a very good idea.
Take note that other types of storage food (canned goods for example) should not be stored along with your produce in a root cellar. The high moisture levels will rust cans very quickly so reserve your root cellar for unpackaged foods only.
Root Cellar Construction
The simplest method is to utilize an unheated portion of an existing basement. As long as you can partition it off to maintain the right atmosphere, and space would be fine.
If you are planning on digging a new underground root cellar space, then you will have a sizeable job ahead of you. Full-scale plans can be found online to help you base your construction but here is the general idea.
First you have to dig a hole. Digging into a hillside will provide easier access since you will be able to walk into the room rather than have to take stairs downward, but then you have to shore up your hole as you dig. Otherwise, you could clear away part of the hill and replace the soil once the building is complete. How big a hole is completely up to you. A small pit can store a little bit of food but a garage-sized room will obviously store more. Consider how much you are going to depend on a root cellar, and base it from that.
Regardless of the intended size of the finished cellar, dig your hole several feet larger in each direction to allow you room to work and manoeuvre. Once the hole is complete, you need create a structure that is sturdy enough to hold the weight of the soil once you refill in around the walls. You do not necessarily have to build in such a way that the roof of the cellar is underground but it will help insulate better if it is. The floor should be at least 7 or 8 feet below the surface to get the cooling benefits.
The cellar can be built with concrete blocks or a wood frame though wood will not last as long since as it is underground. Leaving the floor as bare earth will greatly assist you in keeping the cellar moist. This can also lead to rodents getting into your stores. Lining the floor with heavy grade mesh wire can be a good workaround. If you prefer to cover over the dirt with concrete, you will have to allow another method to build up the humidity. The buckets of wet sand or peat moss mentioned for basement storage will work just fine.
Allow for some venting, with a vent to let out warm air near the ceiling, and another small one to bring in fresh air closer to the floor. If your entire cellar is under ground and the door is parallel to the soil level, then you can use some PVC pipe inside to create your upper and lower vent spaces. Add a sturdy door (with steps if necessary). That is about all you need to do.
How to Use Your Cellar
Unlike most other types of storage methods, you do not necessarily want your food to be sealed up in a container. The whole point of the root cellar is to expose your food items to the environment. Cardboard boxes, open buckets and baskets will all work relatively well. You just need to protect against pests. You can cover your containers with woven wire mesh screen to keep out any rodents, which will be a problem in many dirt floor cellars unless the floor is already lined with screen.
When storing root vegetables, do not wash them first. Leave them dirty, especially if you have pulled them yourself from the garden. Store-bought vegetables will have little dirt on them to start with so its not that important. This helps keep them moist in storage. Also leave on outer peels, rinds and leaves before storage. As natural as possible works best. A little added insulation inside each box is another good idea. Sawdust, wood shavings or even newspaper will work to pack your food in.
You should always keep an eye on a root cellar and inspect your food regularly. Anything that is starting to go bad should be removed immediately as it will spread quickly and ruin an entire basket or bushel. If anything is starting to shrivel or dry out, take it out for immediate use.
There is one additional concern you have to be aware of with storing a variety of foods in a root cellar, and that is ethylene. It's a natural gas given off by some fruits and vegetables as they ripen. Apples are particularly notorious for this. Too much of this gas building up in your root cellar will hasten ripening and further decomposition, which is obviously not desirable. With many root vegetables, like potatoes or carrots, it will cause them to toughen up considerably and get bitter so even if they do not rot, they will be inedible.
The easiest solution is to not store apples at all. But since they are one of the best fruits for root cellar storage, most people would rather not do that. Alternatively, you can keep your root cellar divided with separate vents and fresh air sources so that your fruit can be stored away from the other vegetables. This may be a possibility if you are constructing a sizable cellar in the first place or have a basement area that is divided into multiple rooms.
If neither of these suits, you will have to make do by storing your apples high within the cellar and close to the vents to let the gas escape without effecting the other food.
And apples are not the only culprits here, though they are typically the worst offenders. Pears, peaches, and cantaloupes are other fruits to watch out for.