Apr 20 2013

Welcome back root cellar! The ultimate long term food storage technology.

Of all the awesome innovations of time, the root cellar stands out as something available to both rich and poor. If you got a shovel and you can dig a hole, you are on your way to a storage environment that costs basically nothing to operate.

Root cellars have a few properties we want such as being cool and dark. Additionally, they tend to be stable in terms of humidity although moisture is pretty much the number one thing to be on the lookout for in a root cellar. But they have another incredible virtue.

Where I grew up it was quite common to keep refrigerators and freezers outdoors in winter. The idea is that the Earth produces plenty of coldness in the winter in most places so paying to heat a house in a cold planet and paying more to keep a part of your warm house cold on a cold planet made no sense atall. The trick was to make the door-activated light switch a manual-activated light switch (or even wire the switch in reverse so a low-watt light bulb burned with the door closed instead of open) so you could keep the light on at night and not have everything freeze. Kinda ran them in reverse in winters. Light bulbs are cheaper to operate than refrigerators in hot houses.

Root cellars keep things from freezing as well as from getting hot. And as we know from previous chapters, there’s lots of food like milk and cheese and eggs that we’d rather not have frozen because it reduces their palatability and pleasant character. So a lot of this thing is gonna be about root-cellar evangelizing. I’m anointing each of you to practice and spread this gospel: the root cellar, ancient friend of man, has returned to us in our hour of need.

How to build a root cellar for food storage.

The most basic version is a hole in the ground. Any amount or depth of hole will help but in most parts of the country, you get about 3-4 feet of dirt on top of you and you enjoy year-round thermal stability. In other words it will always be between 40-60°F in a good root cellar no matter what the air temperature is. So we tend to make them elaborate holes in the ground.

Root cellars are often dug into hillsides for convenience, and in this configuration often have a regular door on the front, leading city people to believe that hobbits live nearby. But basically, a root cellar is a room with a floor and walls and a ceiling and about 3-4 feet of dirt on top of the ceiling and outside the walls. The floor is really important in root cellars, often have a central drainage ditch cut into the earth and a deep layer of gravel forming a flat surface on top. This floor drain system is our number one method of controlling moisture in our root cellar. We also usually have vents in the wall near the floor and others up by the roof or whatever top covering you have. This helps you regulate temperature as well as moisture. Ideally, cooler air flows in the bottom vents and warmer out the top.

The moisture issue is huge. In rainy parts of the country, any hole will tend to fill up with water and root cellars can be quite damp, inviting in all kinds of microscopic meanies like bacteria but fungi really love a nice damp dark root cellar. Things like blackmold might force you to abandon a cellar altogether if it gets out of hand. And in drier climates it can be just the opposite. There’s people in the desert that bring cans of water INTO a root cellar to keep things like dried fruit from becoming entirely desiccated. Contact with dry air will seep moisture out like a huge dry sponge. A very patient and huge dry sponge. But in most places you are mostly concerned with the thing filling up with water. So we always find shelves in root cellars and seldom do we see foodstuffs stacked on the ground or floor of a root cellar. And it’s why it’s not uncommon to see temperature and humidity gages inside a root cellar. This is why it’s important not to let your city friends into your cellar to do a magazine photo shoot.

The walls and roofs of root cellars vary. Sometimes they are just dirt. Sometimes the walls are stone or brick or concrete. Sometimes the walls and roof are simple boards which inevitably rot away and become subject to fungi. Stone, brick and concrete are obvious choices for obvious reasons: they resist rot, they can be made seamless barriers against larger biological threats and they are strong enough to where your root cellar can double as a fallout shelter. Wood is often the material at hand, so we try to waterproof the exterior, and for this reason a lot of root cellars end up being boxes that are buried in the earth.

We don’t like pressure treated woods in root cellars. They outgas nasty stuff. Many modern composite materials such as particle boards may also outgas nasty stuff. I know the temptation is to find a rot-resistant material. Cedar and redwood are naturally rot resistant. We’ll talk about some other stuff as we continue.

Root cellar hybrids (& illustrations some day).

There are kind of hybrid designs as well. The hillside root cellar has one problem: one of it’s walls is in direct contact with the very hot or very cold outdoors which reduces it’s effect. In some places this isn’t such a big deal. In some places the Earth is cool enough to where you can have a sunken room with a normal roof on top. Plus you can use environmental factors such as shade trees or placing your door on the north side of a hill for a hillside cellar so it never gets direct sunlight.

Some houses have actual cellars underneath them, as in basements, particularly where it’s cold enough to freeze the Earth itself on top. These make handy root cellars.

Why skimp if you can afford it?

Some really smart people with some bucks at their disposal take a shipping container, apply waterproofing to the outside, dig a big hole and just lay her right in. Fashion an entryway, cover it all over with dirt and now you have a combination root cellar, storm cellar and you are half way to having a bomb shelter to boot.

At any rate, root cellars aren’t really about insulation as they are about thermal massiveness which is kind of the opposite of insulation. Insulation is a barrier between one heat zone and a different heat zone. Thermal massiveness soaks in heat or cold and let’s it go very slowly. There’s this huge interaction between the Earth and the air. The Earth itself emits warmth in winter and soaks it up in summer. It soaks up cool in winter and releases it in summer. This effect is obviously different from region to region, but the more extreme the temperatures, the deeper you want to go. One way to tell is to measure the temperature in your cellar using a thermometer. These rare scientific instruments can only be obtained from such exotic purveyors such as Walmart. Want to know what the soil temperature itself is? Get a meat thermometer, dig a hold and jab the thermometer in at various levels. Don’t wait too long between the digging and the thermometering because the exposed soil is either soaking up heat from or loosing heat to the air, but it will give you a much clearer idea than guessing. The rule of thumb is once you are under 3 feet of dirt, you are temperature-stable pretty much year round. I guess there are places with such a thing as permafrost and maybe a reader from Alaska will tell us how they manage their root cellars. In most places, once you are under 3-4 feet of dirt you are around 50-65 °F. year round. That, incidentally, is the minimum depth range to protect you from the radiation of a thermonuclear detonation. If you are one of those lucky people outside of the immediate blast radius (in which case it’s better to be outside in a lawn
chair because you probably want to be vaporized instantly) but inside the reach of it’s waves of penetrating radiation, this might be of some comfort to you. If you have a good way of sealing off all your vents or even using them for air filtration, you have a pretty nifty fallout shelter coming together. If this is a glum topic, be encourage by the fact that for a while, global nuclear warfare is not our greatest threat. Now it seems to be terrorism or natural disaster, each of which are local or regional in scope. Basically this means if a nuke goes off near you, you have a hope of riding out the initial period and then making it to someplace that’s not as bad effected. In other words, you might actually make it if you are prepared. But this site isn’t about nukes, it’s about food.

Even more tricks! More micro climates inside your root cellar!

By playing all the tricks together we can in effect induce our own micro-climates in storage. The first ones we have if our cellar is well ventilated top and bottom, is that it’s cooler on the floor and warmer towards the roof. I also once saw a cellar that had two rooms, one after another, and the first room had a concrete floor and was pretty dry and the rear one had a dirt floor and kept moister. Just by hanging and shelving things at different heights in one room or the other allowed the owner to really dial in on what balance of temperature and moisture different foods did best in. That was impressive.

Contagion, quarantine and purging of root cellar foods.

I hate to leave my fave topic on a down note, but as I mentioned, a root cellar can become hopelessly colonized by fungi and other stuff. The fungi have microscopic spores that are almost impossible to clean from a root cellar. If your cellar becomes overrun you might develop allergenic sensitivities to it that can make your life really miserable. Some studies seem to show a linkage between mold and childhood respiratory diseases and immune system insults. If this happens, you will be happy if you are one of the few with the sense to have two root cellars to at least half of your provisions will be safe. In any case, you will have to evacuate the overrun root cellar. DO NOT BRING ANYTHING FROM THE CONTAMINATED ROOT CELLAR INTO ANY OTHER STORAGE SPACE. All contents of the compromised root cellar are quarantined. If you think you can still use the contents of the canned good, leave them outside. Pour their contents into bowls to take inside and cook. Don’t even stack the compromised food upwind of a good root cellar. The spores are airborne. A breeze will blow them for miles.

The outsides of non-permeable containers can be washed in bleach and left to dry in the sun and the food in the sealed storage containers is probably fine. Don’t worry about the negative effects of sun this time, this is a salvage operation. Everything else is probably compost.

When a root cellar gets overrun like that, mountain wisdom says it’s over. Purging with fire is one often tried method. Or it was anyway. You’d burn the cellar and all it’s contents. Or just filling them in with dirt. Or sometimes they just got locked and left as an empty space full of memory until some kid finds his way in there. There was some sense of never going back, turning your back on that piece of dirt or hole where the dirt used to be.