Root Cellar 101 - Help Wanted

Below the fold is a guest submission from reader mnborn, a data analyst living in rural Minnesota. It is more of a request for knowledge/advice than our usual essays but food storage in northern (or southern) climes certainly is one basic necessity that is largely supported by fossil fuel powered JIT inventory systems. (Currently most of us use grocery stores as our winter storage caches).

Below the fold are her questions. Old-timers please help her out...;-)

I have read with interest your Campfire posts pertaining to discussions of acquiring practical skills and techniques particularly focused on food production, preservation and storage. Perhaps this would be an appropriate forum to gain feedback from some of your readers on a few ideas I have for the construction of a root cellar. Below is a picture of the spot I have chosen in which to build this. The soil is heavy clay, slope faces northeast and ‘elevation gain’ is approximately 6 feet. My dog marks the spot where I intend on building a root cellar.

Site for root cellar - vertical drop of 6-7 feet. (German Shepherd shown for scale)

Photoshop 'cube' intended place for root cellar, placed back in hillside - roughly 6x8x8

After looking at many designs online, and having one bid ($6000) for a cinderblock constructed cellar, I am thinking an easier and possibly cheaper alternative might be to use 8 ft bunker silo sections. See link attached. These precast sections of concrete come in various sizes but I’m considering 6’(H) x 8’(L) for an 8x8 root cellar. Other options I’m considering are poured concrete (pricey no doubt), another old farmer told me ‘in the old days’ they would dig out a cave and line the wall with a thin layer of cement. Additional ideas are greatly appreciated; especially those that cost less and/or are simple enough that I can assist in the construction.

Something like the above would be grand, but likely undoable without premium labor. I'm willing to spend in the $4,000-$6,000 range for a quality permanent cellar and will add my own labor/time to the effort (and possibly my internet addicted boyfriend)

I am also curious to know how many of these skills related to basic needs (e.g. food storage) are still around or if two+ generations of oil/electricity have erased them culturally -even the Amish workers near me didn't know what to make of my cellar request.)

Thanks in advance,

One issue with digging in is moisture

Cool but dry is what you are after

You might consider a concrete septic tank at ground level and covered with straw bales or foamed

Dry for some stuff, like winter squashes. Apples and potatoes store best in a root cellar at about 90-95% humidity. Lack of building materials isn't the only reason many of the old ones had a dirt floor, it served a purpose of keeping the humidity up (if it got a little dry you just wet the floor). The down side is that little furry mammals can burrow in and munch on your provisions. Coarse gravel on the floor alleviates that somewhat while still enabling humidity control.

YES, dry vs humid depends on the veggie or fruit. Re the furry critters, the cavity could be lined with hardware cloth to keep them out.


I'm in the same boat...just recently became obsessed with root cellaring. I don't have much advice, being new myself, but I'm in the middle of this book and it seems to be a great source of info, both on design and building various types of cellars but also as a reference for what to plant when, and how to store it.

Root Cellaring: Natural Cold Storage of Fruits & Vegetables

Good luck with the project!


The Root Cellaring book is the bible. It has many examples of what can be done. Our home (1991 vintage) isn't suitable as there is no cold space anywhere. Space can be under the deck. One can distribute caches of food in the ground or under straw. Fridges or freezers can be buried in the ground as they're nicely insulated ... These are all small storage structures. An old vehicle embedded into a hill is another solution. The metal, round 4+ feet diameter culverts might be a solution as they are designed to be buried and handle compression forces. Reusing silo cylinders is a neat twist - but they're designed for expansion, not compression - but concrete ones should do well. Concrete well casings are a bit small; but may be suitable. Some people have used tubes in the ground - with strings to pull things out and poles to push things in.

You want an earthen floor, sometimes concrete.
Cool and dry isn't always what you want. Many things require cool and moist and some tolerate warm and dry (onion, squash).

It seems to me that the miracle of getting excellent apples; nearly a year after they were picked is all due to amazing control of storage conditions (nitrogen gas, temperature and humidity).

Clay soil will be a bugbear for you. Dig a hole and you might as well call it a pond when it rains. You'll need drainage (pump?) as well as vent holes.

Second on that book for a reference. Essential information in it if you are new to the subject and serious about building one.

Here's a link to a pdf about cellaring to add to what you must already have:
It looks pretty flat where you are and snow drifting might not be a problem, but I'd just say be mindful that you need to get into the cellar when there's snow on the ground.
I just built a pantry in a space between my house and garage. It was already insulated on three sides so I needed to put in the floor, remaining wall and roof- all insulated, of course. It will NOT be heated and I hope will serve somewhat a root cellar. And, I don't have to dig through the snow to get there.
And lastly, we recently dried some strawberries and were discussing various ways to preserve stuff. One of the suggestions was vacuum packing and we arrived at evacuating a mason jar by drilling a hole of appropriate size in the lid, inserting one of the rubber stoppers use to evacuate air from a bottle of wine and then used the hand pump to pump the air out and now have strawberries dried and in a vacuum mason jar

In the 1970s, I helped my father a build a root cellar in our backyard. This was stimulated by the availability of beams from a neighbor's house that was being razed. After I dug the hole, a light foundation was poured, and block walls were laid. 6 x 6 beams were used for the roof, covered by tar paper and earth. Two ventilation stacks were placed. This was very good for potatoes, fair for onions and carrots and so-so for squash. We used this extensively to age beef, elk, deer, and pronghorn.
Last year one of my father's dogs was walking over the root cellar when the roof failed, causing a spinal cord injury.

I think the idea of a reinforced concrete structure is quite good. Ventilation should be considered.

If you are flush with cash by all means go with a contractor.

But I believe you can do just as well with a couple of handy men and be your own contractor.

Just remember that this advice may only be worth what you are paying for it.!.

Hire a backhoe to excavate the hole.Move the excess soil up hill above your cellar to make it easier to backfill later by hand if necessary.

Remember that the price of the machine for such a small job is mostly a show up charge,so if you want a water line to your garden or chicken house or a stump removed,etc,now is the time.
Work is slow.Don't be afraid to dicker the backhoe price and consider splitting a days work with a nieghbor .
Remember that the cubic capacity of your cellar is going to increase as the cube of the measurements.The bigger the better,as far as bang for your building material bucks go,and that cooking breakfast for one or two is nearly as much work as for six eight.

Make the excavation at least two feet longer and wider than the planned OUTSIDE DIMENSIONS of your actual walls.This will give you a foot of working room and you will need it!

Slope the floor at least four to six inches from the back toward the door,downhill to help with any future drainage problems.

Plan on covering the floor and entrance walkway with gravel.Sand sticks to your shoes and so does damp or wet clay.You have enough housework as it is ,right?

Used cinder block,eight inch size if you can find them ,new if you can't,make very good walls.

They do not have to be skillfully laid.

dig a trench where the walls will go twelve inches wide and six inches deep and pour it full of concreteand build your walls on this foundation if you feel the need,but you can start right on the ground if your cellar is small-say six by eight feet.

Use plenty of mortar and if you can't get a reasonably straight and even wall,pour the block cores full of concrete as you go up.

Try to borrow a mixer or rent one if you must.

Tar the outsides of your walls liberally with a water proofing compound made for that purpose.

As you backfill use some gravel at the ground level-at least four inches and lay a perforated plastic drainfield pipe on the gravel,cover with at least four more inches.

Bring pipe end out on downhill slope so any water from really heavy rains can easily drain away.

repeat at halfway up walls and near top ,cellar should be at least eight feet deep to top of walls.

Top of walls should be a foot at least below grade of lawn.

The roof is the big problem.

Personally I would go with salvaged steel channels or i beams and tar them until I was sure all spots are thoroughly covered.Thick iron so protected will surely outlast you and your children too if you keep an eye on it.

At right angles to your roof beams use thick pressure treated wood or some very durable wood such as black locoust or cypress boards as sheeting.Small gaps are ok,up to a half inch max.

Cover that wood with a layer or two of good thick rool rubber roofing ,or several layers of roofing felt.
make sure the rubbver or felt extends out and over edges and construct roof sio it has slope to drain .

Backfill and then cover roof with a foot of good topsoil that will support a good grass sod.The roof needs the thickness for thermal mass and insulation from both summer heat and possibly winter cold in your area.

Backfill the downslope wall to as nearly the same original ground contour as you can without making it hard to get to the door.Be sure the walkway to the door has enough slope to drain.

Build your door nice and thick and seal it well with caulk to keep out hot dry air.

Som scientific wild guesses as to your costs :

300 bucks,nieghbor one horse farmer paid in cash no reciept..Eight hundred if you are way out in the boonies and contractor is on the road a couple of hours.

block and mortar.five hundred to a thousand depending on size and how good you are at finding treasure.

salvaged steel and rust proofing three hundred bucks give or take.

Door ?fifty bucks?

Rubbber roofing or felt ?haven't bought any in years,maybe a couple of hundred max.

Sheeting lumber fifty square feet two inches thick,no idea in your area but not overtwo hundred surely.

gravel two hundred to four hunderd for a small truck dump truck load,the hauling is usually more than the purchase price.

Two good handy men for five days another thousand plus snacks and lunches and some fresh veggies.
(Good handy men = have calluses and muscles and at least one of the two has five years plus general construction experience.)

Thirty five hundred bucks or so is not chicken feed at my house but you probably can get a six by eight by eight foot deep cellar for that that will last indefinitely.

It will pay for itself if you use it.

You need the advice of a local carpenter or iron wrrker to settle on the spacing of beams,need for posts to support roof etc,depending on your materials and design size.

Remember that these are only suggestions for informational purposes.Mr Murphy WILL make his presence known when such projects are undertaken and if someone with adminisrative and problem solving skills is not in charge,it's best to hire a contractor.

my puter said no more comments can be added; til now.

after reading oldfarmermac i thought i knew the reason. hire him!!!

oldfarmermac is a treasure house>

Ah Thank you for the detailed suggestions. Exactly what I hoped for! Drainage will be an issue and I'd like to ensure everything drains away; in all relevant directions. One more would I vent? And could I use an 'elbow' vent to prevent rain water from running inside? Also, were you able to pull up the link provided? What do you think about the bunker silo sections? Can you think of any drawbacks in using them? They are very common here at the dairy farms and there's a manufacturer just down the road from me.

An inverted elbow vent should work just fine if you cover the end with a wire screen to keep out whatever critters may try to use it as thier home or route into your cellar.

I personally have never had any experience with bunker silos and can't comment on using the component parts.

A a depth of one foot,soil here in sunny spots that is moist and has a good grass sod growing on it feels nice and cool to the touch even after a week of ninety plus afternoons.I'm guessing but I think that if you have grass evaporating water for you that a foot of soil on the roof is plenty to keep the interior nice and cool,especially if the walls are at least six feet high,and the wall on the "downhill"side is backfilled to the maximum practical extent.

The thermal mass effect of soil insulated by a heavy growth of good thick grass is awesome.i have enjoyed windfall apples that fell into such grass in March after heavy snows and zero temperatures in Janurary.

A six by eight cellar could serve as a tornado or fire shelter for maybe as many as twenty people but suffocation might be a real possibility in case of fire.

You could just leave the door open until the last minute in the case of a tornado.

Nobody builds root cellars as such around here any more,but there are many barns built with basements sunk deep into into hillsides.We have such a masonry barn on our place and we use the basement as our root cellar.

My suggestions are more or less a short summary of the techniques used to build cheap sturdy barns of this type by the local farmers,with the exception of the roof.

I have seen such roofs as I described a few times in my travels and the folks who built them filled me in on the details.There are also descriptions of such roofs in several old books that I have read,but in those days they had only wood,no steel or rubber roofing.

Nice advice farmer mac. I would also advocate using cinder blocks. I have built a couple of kilns using cinderblocks for the foundation. Another hint on the floor is to use crushed stone with some small rock in it to set a level (and sloping toward door like advocated above) foundation. To really set the bottom row of cinder block, consider pounding in several lengths of rebar through the holes in the cinderblocks, then fill the bottom blocks with concrete.

His advice on paying for a backhoe and having the fill dirt for later backfill located conveniently close is very valuable.

One more roof idea is to build an arch using bricks. You can find some kiln making books that show you how. Look for anagama style or catenary arch style, and you should be able to use bricks to make the roof. You would not be using high temp refractory bricks though of course. Basically you build a wood form inside to create the curve you want. This looks a lot like an upside down boat, but the boat bottom only needs to be strips of wood, or an arch of plywood. Then you build the arch on the outside using a little mortar, but mainly trying to fit in the bricks very snugly. You can use arch bricks but I have also used standard rectangular bricks. Once the roof is finished and set, you go back to where your door way is and tear out the wood form. You may get lucky and be able to slide out your form, but on complex curves or domes, I used a chain saw & hammers, and anything to get the job done. Once finished you will have a strong load bearing brick roof that can be covered with more earth.

For more info on how to build the arch, find or borrow a copy of "The Kiln Book: Materials, Specifications & Construction" by Frederick L. Olsen. If you like this idea, it would be good to befriend a potter who has built a few kilns to get some on the ground advice. The arch construction would be the same. Also consider using second hand building materials. You very often can get old used brick for free. Cinder block is ridiculously cheap at home depot.

Here's a picture showing an arch going up:

I believe that an arch roof would be a very good solution -but only if you can find someone experienced in building them to take charge of the job.

It seems unlikely that learning by doing would be worthwhile in this particular case,given the length of time needed and the possibility of an accident if the supporting framework is not built just right.

My dream root cellar is a combo tornado shelter, food storage and sleeping lair for when the weather is too hot or cold if the electricity is out or I want to conserve energy. Ideally it would be at least 8' X 15.

The question I have is how much soil on the roof is sufficient to insulate the cellar to maintain the temperature in the mid to low 60's. And is it possible given that I will need to have ventilation shafts above ground? What is the exchange rate for the air?

I don't mean to hijack this post, but as long as there is expertise out there, feel free to respond.


Frost line depth (that is if you have freezing winter temps)? Temperature don't stabilize completely for several more feet, but the fluctuations dampen with depth. Ventilation for temperature control is something worth looking into and is a bit arcane. When cool temperatures arrive in the fall, cool air flows in one vent, warmer air in the cellar flows out another vent. It kind of the same sort of thing that happens in the ice cave in New Mexico. Natural convection currents in winter allow cold air to pool in a collapsed lava tunnel, when temps warm up in the spring the convection currents stop. I don't know the precise details of the cave but there would have to be a couple of favorably placed natural vents for the phenomenom to occur. The cave stays at 31 deg F in the summer months. Same principal with the cellar vents, but you have to close and open the vents as the temperatures dictate in the cooler months to get the chilling convection currents.

I don't know how long you would be able to keep it at refrigerator temps as it warms up in the spring -- an acquaintance that has since passed paid particular attention to the venting in his root cellar, and it was cold well up into the summer. He complained about kids going into it because opening the door too much warmed it up.

Thanks Barrett, it seems like a vent in the roof and one originating at floor level might be able to take advantage of the differential temps to get a draft going in the preferred direction with one or the other dominant.

I would especially like to keep it cool in the summer for an escape from the heat for sleeping. Closing both vents except when in use might work. And not opening the door during daylight hours.


what about very bad weather/wind; can't the root cellar double here? also even use it to survive a bout of radiation?

thanks for the post & ideas as i'm about to deal with a dugout crawl space 'room' & i hope to set it up to store foodstuffs.

4 season gardening by elliot coleman has a design for making a root cellar in a basement. it is basically an insulated-from the basement- concrete block room with outside vent/cold air entry. he has great info on root cellaring there.

I've observed that potatoes and turnips seem to keep for months undisturbed in the original cool soil so that cellar storage may not be as necessary we think. However there are several other reasons to have a roomy earth cellar.

For a start several people survived the Melbourne bushfires in pre-built bunkers. Note that more than 100 people perished in their homes and nearly as many trying to escape by car. The cellar could also be a refuge in a heatwave. It can block out the sound of noisy neighbours assuming you didn't get invited to the party. Lastly you might want to store root vegetables. I suspect that a pit suitable for growing mushrooms would be too damp and mouldy for habitation.

Inspired by a stint of opal digging in the Australian outback I have dug a cellar into a hillside. It is about 4 metres deep and 6 metres long in a bank of weathered dolerite now turned into a gritty white clay. It has a light proof door and a ventilation shaft. After heavy rain I realised it will need shoring after chickenwire is nailed to the roof. When it is dry I will whitewash the roof and walls with a silicone and cement based render. The clay steps are reinforced with wooden slats. I'll install a 12v reading light powered by a gel battery perhaps with a 30w solar panel on the surface.

I'm willing to spend in the $4,000-$6,000 range for a quality permanent cellar and will add my own labor/time to the effort (and possibly my internet addicted boyfriend)

Get a new boyfriend, seriously.

I'd say that anyone posting regularly to Internet discussion forums has little room to throw stones on that one.

Root cellar safety

Please take this advice seriously.
Many people have suffocated due to gas (mainly CO2) build up in root cellars.
Other than that good luck with it all. We stored all of our potatoes, carrots, beets onions and cabbage in our cellar in northern Ontario in the 1950s and 60s.

What about using standard cement sewage pipe fittings to build a cellar?

Or, alternatively, any other scrap lying around like a decommissioned fiberglass in ground swimming pool.

One of the considerations in building a root cellar is that if there is civil unrest, the cellar need to be somewhat hidden and not obvious from a distance.

Stored food caches will be one of the most attractive targets for robbers.

There should be giant sections of cement pipe that can do the this:

Stop with all the advice about Backhoes and FF crapola...get a few neighbors, a new boy friend (hell, I may be interested in that job), and start digging. The advice for block is good, recycled stone would be better. Brush up on the construction of an arch. Look at any history book, they will last thousands of years. Don't think in the short term BAU of a MERIKAN. Think about any future generations that will pass thru the place. Don't just build it to outlive you, build it to outlive generations of you.. Make it a Legacy. Think....

Make it as big as you can, relocate your dwelling into it, with section rooms seperated off to one side for roots, another room for fruits. Different zones for different products. Done right, with vents and Super insulation, you could heat it with a candle. With that amount of money, barter and trade for labor and goods. Think in a different direction from your current mindset. Get off the machine mind set. Natural materials. You will be protected from the coming storm, unlike so many others. Those that learn to live underground will be the ones who will survive the coming days.

Making a shelter is one problem.

In most parts of the country, if the shelter is underground, you have an issue of water. Floods, etc.

Furthermore, there is another issue, of security --- an underground home will not protect anyone if there is a highly visible entrance / exit / vent.

Those things need to be architectured to provide natural camouflage, and also to perhaps, make it inaccessible to the casual intruder.

Doing so without limiting your own access is a lot more difficult than it sounds.

The cellar have to be loaded several times a season, and regularly accessed the rest of the time.

Not that easy.

My understanding is that you should not mix roots and fruits

Evidently the temperature/humidity requirements are quite different, and the fruit gives off a gas that causes spoiling problems with the vegetables (or vice versa)

So if you wish to store both you may want to look into building a seperated pair of smaller structures.

Do go talk to your local pre-cast concrete manufacturers. They may be able to put together a nice structure for you that can be lowered right into the hole. I had them make me a cistern and they had no problem including lots of embedded plastic pipe connections per my design. Once the tank was set I just had to connect my pipes and bury it. You will want to embed some large pipe connections for things like fresh air intake and exhaust, and if possible a bottom edge drain incase of flooding...

...and the fruit gives off a gas that causes spoiling problems with the vegetables (or vice versa)

Fruits give off ethylene (C2H4) which promotes the enzymatic actions involved in ripening. Vegetables respond to ethylene by getting limp or soft, and spoil sooner. Apples produce a lot of ethylene, other fruits not so much. This can be exploited at home -- the old trick of setting peaches (for example) out in a brown paper bag to ripen them works by increasing the local level of ethylene, which can be increased further by adding an apple to the bag.

If you have a basement that is unfinished (or at least partially so), consider building a basement root cellar. Best if you build in a corner where the basement walls are mostly below ground level, to the size you project you will need. The interior walls are insulated to keep the root cellar at the ground temperature, adjusted by the amount of winter air you choose to bring in.

My mother grew up on a farm in the Depression that had both a root cellar under the kitchen as well as a "hole in the hill" storage for more space. The hole in the hill was described as having a door much like the one pictured in your intro, with a floor covered with straw. Turnips, beets, onions, and likely other items were laid out on the straw, then another layer of straw was added, then another layer of vegetables, and so forth. The root cellar was used for carrots (in buckets of moist sand), herbs (after they had been dried), mason jar canned goods, crocks (sausage?) and other items I cannot recall. I know they killed one or more pigs in late November as a regular practice, so I'm speculating the crocks contained sausage (though there was also a smokehouse at one time).

Kudos to oldfarmermac for his contribution (and many good ones from others as well).

I had a root cellar similar to this built in my basement last winter--too late to really use, but I did have the opportunity to experiment with temperature control. I live in Missouri, where winter weather can be quite variable. You definitely need ventilation. The book that has been linked above is invaluable for explaining how to use 2 pipes to create air circulation, and it really does work well. I kept my root cellar temperature in the low 40s most of the winter. It is warm now, in the Midwest summer, of course.

I have no practical experience yet, other than a few potatoes I put in there last winter, but the Root Cellaring book does say that, although there is a theoretical risk of putting apples with potatoes, due to the ethylene gas from the apples, the authors and most people they have talked to DO store them in the same cellar, without significant problems.

The thing that seems the most complicated to me is the variable temperature and humidity requirements for different crops, but the book again has good tables listing what does best under what conditions, and my plan is to try to find some sort of happy medium with the crops I plan to store. Their general advice is that onions and squashes are better in a drier, warmer place than the root cellar itself.

Good luck to you!

It wasn't a root cellar (that was in the basement, cooled by a shallow underground stream) but my dad says that back on the farm in Ontario, Canada, they used to store their potatoes & other root vegetables right out in the garden. They dug a shallow pit (I think about 3' deep), lined it with a thick layer of hay, then started layering in the vegetables. I believe he said they laid the potatoes about 3" apart from each other. After each layer of vegetables, they put another layer of hay, and built up a pile this way. More hay and then a thin layer of soil was placed on top. A flagpole was stuck in the top so they would be able to find it in the winter when the snow was deep. Apparently it worked quite well through the winter season.

We have had an organic farm for about 17 years. I am retired now.

We live in an old stone farm house with dirt floor basement, unheated and originally used for cows.

We store potatoes in wide mesh potato sacks on pallets in the basement and well covered with black plastic. They keep very well and in fact we are still using last years potatoes as well as digging fresh new potatoes. An organic farmer friend of ours stores many tons of potatoes that way but on a second floor of barn with plank flooring. He also covers well with black plastic and has a back up heating system just in case it becomes unusually cold. They must not be allowed to freeze, of course, unless you want to make Chuño.

Carrots are carefully packed in alternating directions and unwashed into wooden crates with space between slates. These are also placed on pallet and covered with black plastic but we occasionally moisten the soil below the carrot pallets.

Squash do not like low temperatures or moist air. We stored ours on a heated porch, on wooden board shelves. An ideal temperature is about 15-18 deg C and humidity about 30-45%. Too dry and they dehydrate and too humid they mold and spoil. Good ventilation is important. Stagnant air brings on molds and spoilage.

I second this and Will Stewart above for the use of a basement. The most foolish thing today is to buy or build a home without a basement. Discount the particle board flooring or photo finish cabinets, the worst attribute is lack of a basement. If water is a concern, then the home was probably not sited properly.

We've used both a "conventional" root cellar dug into a hillside, and a basement section. I opt for the basement. In addition to easy access in heavy snow, the basement has kept produce from freezing better. It's a shift between ventilation and freezing risk in my experience. We've used an incandescent bulb to get around this, but still had edge freezing.

I recommend treated wood or stone/concrete, but wonder about using the new composite decking where structural strength is not a concern.

With our basement storage the last 8 years, we are able to keep potatoes til May. Kennebecs seem the best keeper for us. Not recommended, but we do store ~15 bushels apples with the spuds. Carrots are stored in the basement in a sheep trough, filled with slightly moist sand. Squash are just set on cardboard on the floor or shelves. Temp range for the winter is between 35 and low forties, warming into the spring. Basement also has a propane furnace-insulated 2x4 wall between storage and furnace. We won't heat any portion of the basement, save what radiates off the forced air furnace.

You could just pour a concrete roof, tie it into the wall with rebar, mold in concrete trusses. It would take a lot of scrap lumber but it would be cheap and indestructable.

true-but pouring concrete above ground level requires a VERY strong form the same size as the roof.

It's easier to use the form AS the roof.

But the concrete would last hundreds of years if you use a really good mix-plenty of cement and the soil chemistry is somewhere near neutral.

Oh absolutely, I used to watch condos being poured. under each concrete beam I'd have 2 jack posts and a timber, and a forest of props elsewhere. But it would not require much in the way of carpentary skills either. Forklift pallets could probably provide much of the material.

This is the kind of building project where you adapt it to the site and choose the building method based on the available tools, scrap or good offers.

One very old advice is to use two doors since that is an easy way to get good insulation and it fits well with manny ways of building the cellar and it also ads a little better rodent protection.

And for the doomes, an earth insulated root cellar is a good fallout shelter, the major difference is that you want a 90 degree bend to the entrance with earth behind it have no free line of sight into the cellar.

John Fisher-Merritt has a large root cellar and much experience. He is just south of Duluth. We lived near Walker, around Longville,MN.
John Weber
Rising Rock Orchard
Longville, MN 56655

Here is an article on their root cellar.
Root Cellaring and Computer-controlled Ventilation for Efficient Storage of Organic Vegetables in a Northern Market
Principal Investigator
John Fisher-Merritt
2612 Cty. Rd. 1
Wrenshall, MN 55797
Carlton County
Project Duration
2001 to 2003
ESAP Contact
Mark Zumwinkle
community supported agriculture, organic vegetable production, post-harvest handling, season extension
Project Summary
We designed and installed an automated temperature control and monitoring system in our new root cellar. We demonstrated the efficiency and cost effectiveness of using the earth’s natural temperature differences to heat and cool a space for vegetable storage. The environmental benefits of this project are tremendous. Instead of buying produce trucked in from thousands of miles away and stored in warehouses heated and cooled by fossil fuels, our customers are purchasing high quality produce, grown locally, and stored using a minimum of energy.
Project Description
Our family owns and operates a certified organic Community Supported Agriculture (CSA) farm 25 miles southwest of Duluth. We offer 100 summer vegetable shares (available from mid-June through mid-October) and 36 winter vegetable shares. The farm is diversified, producing meat chickens, turkeys, and eggs. The meat chickens and turkeys are raised in pastured poultry pens and add soil fertility to our vegetable crop rotation. The winter shares include a variety of vegetables for freezing, canning, and storage including carrots, beets, squash, and potatoes. Winter shares have worked well but participation has been limited because most customers lack adequate storage facilities in their homes.
Our marketing strategy also includes wholesaling vegetables to the Whole Foods Co-op in Duluth. We have a reputation for high quality with the Co-op clientele and have worked hard to maintain a good relationship with their produce department. The produce manager recognizes the superior quality of local produce and is eager to obtain vegetables locally over a longer portion of the year.
Our labor force in 2003 consisted of our two sons, Ben and Janaki, our friend and longtime employee, Dave Hanlon, a former intern, Teri Sackmeister, and one short-term intern, in addition to myself. It is very rewarding to have committed, long-term workers.
In 1999, we decided the time was right to build a root cellar to extend the period of time we could provide vegetables to both the Co-op and our CSA members. In the summer of 2000, we built a 24’ x 32’ root cellar with an attached 24’ x 20’ packing shed. The root cellar has a number of unique design
Unwashed carrots stored in pallet boxes.

features. It is built into a hill so that a van, pickup truck, or small tractor can back completely into the structure. This allows for efficient loading and unloading of vegetables.
Fans were installed to draw in outside air and lower the root cellar temperatures in the fall. A ventilation control and monitoring system was installed. Whenever the outside temperature is lower than that of the root cellar, the fans come on and blow in cool air until the inside temperature reaches the desired level or until the outside and inside temperatures equalize.
The monitor stores temperature information for each of three rooms in the root cellar and the outside temperature every half hour. This information can then be downloaded and printed out. The monitoring system enables us to document the overall performance of the root cellar so we can pass this information on to interested parties. Cindy Tong, University of Minnesota post-harvest handling specialist, maintains current temperature data on a web site at:
Gross sales increase due to the addition of the root cellar (over 2000 baseline). In 2001, the root cellar increased our gross income by $10,000 in CSA sales and by $2,400 in extended season sales to the Whole Foods Co-op. We limited the expansion of CSA winter shares until we could ensure our ability to operate the root cellar dependably. We experienced an ongoing increase in demand from our committed CSA customers.
In 2002, season extension increased CSA sales by $10,500 and Co-op sales by $3,000 over the 2000 baseline. We achieved the steady growth and customer base we planned for.
In 2003, the root cellar increased our income over the 2000 baseline by $10,750 in CSA sales, $5,000 in extended season sales to the Whole Foods Co-op and $2,600 in extended season sales to Roots and Fruits, a wholesaler in the Twin Cities.
Control and monitoring system performance. The control and monitoring system was more time consuming than we had expected. Time was spent monitoring the equipment, reporting malfunctions, replacing a computer, and learning how to make graphs. We had problems with motorized dampers not closing and temperature sensors not being accurate. When these mishaps occur, the entire stored crop becomes vulnerable to potentially devastating temperature swings. The entire system is vulnerable to electrical storms. We would have been completely baffled without the assistance of our sons, Ben and Janaki.
Root cellar improvements. In 2000, the cellar walls were insulated on the outside with 2” Styrofoam to a depth of 2’. At the 2’ level, the ground was insulated horizontally from the building to a distance of 4’. This allows the building to be maintained at the earth’s ambient belowground temperature (approximately 45_F). The earth’s thermal mass serves both to heat the structure in winter and cool it in summer.
In August, 2001 we were forced to re-insulate the outside wall and surrounding surface due to excessive settling of the previous year’s backfill. A gap had developed at the top of the foundation, allowing any surface water to funnel down the foundation wall. We decided to take this opportunity to extend the horizontal insulation from 4’ to 8’ since it would cost only $400 more than the original design.
This improvement paid off during the summers of 2002 and 2003 by keeping our root cellar between 50_F and 55_F all summer long. This compares to an average of 60_F to 65_F in the summer of 2001, even though the summer of 2002 was hotter. The newly extended insulation also contributed to the speed with which we were able to cool the root cellar in the fall.
During the 2002-2003 winter months the new insulation continued to pay off. We had no snow cover and in many areas the ground froze down to seven feet. Our septic system froze and did not thaw until mid-June. We would likely have had to heat the root cellar if we had not extended the ground insulation.
During our first season of using the root cellar, we discovered that our original layout of the storage rooms was not practical. The squash room got too cold because it had too much outside wall surface area. To remedy the problem, we switched the squash and potato rooms. The squash room is now insulated and has a heater for those times when the passive system cannot keep up with the warmer temperature requirements of the squash. The heater is controlled by the same computer system that manages the rest of the root cellar.
In 2001, we maintained a temperature of 45_F in the squash room. We experienced unacceptable losses from spoilage at this temperature. On the advice of Cindy Tong, the post-harvest handling specialist at the University of Minnesota, we raised the temperature to 50_F and installed an overhead fan to insure good air circulation.
Managing the root cellar takes more time than we expected. It is not unusual to spend three to four hours a week culling squash and tracking the condition of the vegetables. In the winter of 2001, unusually warm weather kept us hopping.

Slatted cold storage bins for root crops.

At times, temperatures remained too warm to cool the root cellar, even with the cooling fans running. This caused the fall carrot crop to sprout and the carrots had to be rewashed.
The 2002 fall harvest season provided cool enough temperatures to cool the root cellar before harvest. Unfortunately, heavy early frost in the field damaged the potato crop, creating the need to hand sort blemished tubers.
We installed two large auxiliary fans to hasten the process of cooling the root cellar. At harvest, we opened the root cellar door, turned on the fans, and rapidly cooled the facility. Once this initial cooling process was done, the smaller fan that came with the temperature control system was adequate to maintain optimum winter temperatures.
In 2003, we wired an extra outlet that activated whenever the computer-controlled ventilation system called for outside air. This allowed us to run three large fans set in the 10’ outside doorway during the initial cool down period. We felt comfortable leaving them plugged in all night, even with temperatures in the lower twenties, because they would come on only when needed.
Winter squash storage and handling. In the summer of 2003, we built a shed for curing winter squash. We wanted to improve the quality of the squash and reduce labor involved with harvest and storage. The building is a 14’ x 30’ inflated hoop greenhouse attached to the south side of a barn. It has two 15’ x 10’ sliding doors that open into the barn, giving us full access to the curing shed with our skid-steer loader. Material costs for the curing shed were less than $1,000.
We cure the squash on large storage racks and then carry stacks of ten storage racks, complete with their dolly, to the root cellar with the skid steer loader. This eliminates the labor of unstacking and restacking the 80 lb racks by hand. Because the system is efficient, it tends to get done when the squash are ready, rather than waiting for the rush of fall work to subside. So far, we have experienced significantly less squash spoilage in 2003 compared to previous years.
The carrot harvest was abundant in 2003. We ran out of bin space and purchased 38” x 38” x 22” pallet boxes that hold 500 pounds of carrots each. We purchased a small but powerful hydraulic lift for moving and stacking pallet boxes in the root cellar.
Along with the increased storage capacity, the boxes are being used for two experiments. First, we want to see if washed carrots store better in the boxes or the bins. Theoretically, they should store better in the boxes because the 34_F air surrounding the boxes should keep them cooler than the 45_F floor and walls surrounding the bins. Second, we are testing washed versus unwashed carrots for storage quality. It takes more overall labor to wash carrots in winter compared to washing them immediately when they are dug. Not washing allows for quicker harvesting, making it possible to choose a harvest date just before freeze-up.
The root cellar project has proven beneficial in an unforeseen way. The added space provided by the 24’ x 20’ packing shed promotes greater organization. The shed is attached to the root cellar and has storage space for boxes used in shipping. The shed also provides a place for cooling vegetables (we immerse them in water). Pre-picked
vegetables like zucchini and cucumbers reside next door in the root cellar, just steps from the delivery boxes. The addition of tables to the packing shed made handling of delivery boxes much easier. During construction of the root cellar, it appeared to be quite a bit larger than it needed to be. However, now that it is in use, we are finding that it is just big enough. It takes a lot of room to pack 100 boxes of produce.
The addition of the root cellar evened out summer and fall workloads. There is a cool space for the pre-picked vegetables in the summer and fall harvest begins earlier. We are no longer dependent on guessing when early freeze-up, snow, or other bad weather may occur.
Cindy Tong is conducting a quality control experiment in the root cellar. She is monitoring the change in eating quality of the vegetables over time. Measurements include weight loss and sugar content throughout the storage period. She is also comparing the performance of our root cellar to laboratory controlled storage.
Management Tips
1. Expect to spend several hours each week managing the stored vegetables.
2. Take time to design work space flow to optimize the use of both the root cellar and the storage shed.
3. Place the cold-loving vegetables against the walls with the most exposure to the outside.
4. Get to know the long-term storage needs of each crop in detail. A difference of 5_F one way or the other can mean success or failure.
Troy Salzer, Carlton County Extension, Carlton, MN
Mike LeBeau, Conservation Technologies, Duluth, MN
Michael Karsch, Whole Foods Co-op, Duluth, MN
Cindy Tong, Department of Horticulture, University of Minnesota, St. Paul, MN
Project Location
From Duluth, take I-35 to the Carlton/Scanlon exit. Turn left on State Hwy. 45 and go to the stop sign in Carlton. Go straight on Cty. Rd. 1 through Wrenshall. After the intersection with Cty. Rd. 4, we are the 7th mailbox on the left. From the south, take I-35 to the Wrenshall/Mahtowa exit. Turn right on Cty. Rd. 4. Go 15 miles and turn right on Cty. Rd. 1.
Other Resources
Contact Cindy Tong for detailed results of the vegetable quality experiment. 434 Alderman Hall, 1970 Folwell Ave., St Paul, MN 55108, 612-624-3419. Email:
Web site with information on construction expenses, a schematic of root cellar insulation, and quality of winter stored vegetables:

I built a root cellar two years ago. 8 ft by 8 ft by 8 ft high, made of concrete (cinder) blocks. Cost me CDN $3,500. I hired a backhoe to dig the hole ($170). I built the forms for the footing, then had a cement truck pour the footing (about $150). I hired two bricklayers to build the walls (two men, two days, with me as the assistant to carry blocks = $500). The blocks were another $290.

I designed a catenary (arched) roof, and hired a contractor to build the form and pour the cement. The roof alone was $1,100 (four men, two days), but it is a thing of beauty. A curved ceiling helps drain the condensation to the side so it doesn't fall on the produce and ruin it.

Four things are important. [1] Lots of moisture: the floor should be dirt or crushed stone, not concrete. [2] Ventilation: need an intake and an exhaust, with air flow. [3] Good drainage around the cellar so it doesn't flood. It have an 18" layer of crushed rock all around the root cellar. [4] Deep enough, or buried with a thick enough layer so the natural heat of the earth keeps it above freezing. On very cold winter nights, an electric radiator set real low will keep it just above freezing. Old timers used to burn a kerosene lantern. I average about 4 cents/day on electricity to heat my root cellar in Nova Scotia.

The bible on root cellars is "Root Cellaring" by Mike & Nancy Bubel. You can still order it on line.

If you're interested I can put pictures on line of my project.

If you're young and work hard, you can do most of the work yourself: dig the hole, learn to mix and pour cement, lay the brick, and build forms to support a roof.

I buy produce in bulk from the local farmers: potatoes, carrots, turnips, parsnips, and apples. I can get beets, but my family doesn't eat them. For the six months from October to April, I don't buy any of these vegetables from the grocery store. In July, my carrots are still good.

I live in the middle of thousands of acres of prime farm land. When 50 lbs of potatoes or turnips go for $10 at harvest time, it just doesn't make sense to operate a garden.

When the SHTF, we will can and make preserves, and store it in the root cellar. I estimate I could store enough food for four families.

anyway you can provide a picture of your arch? (if not, send to my email and I can upload it)

Here is an example of a company that specializes in building wine and vegetable cellars in Germany. Includes some pictures and descriptions that are illustrative.

Glad to oblige.

The ribs. The curve was calculated with a spreadsheet. The height was plotted at 1" intervals on a sheet of 1/2" plywood, then cut out.

Lotsa rebar.

Final touch: troweling. Barry and his crew were pros.

2" x 4" supports close together. The concrete roof was about 5,000 lbs wet. Each post supported about 250 lbs.

The finished product. It was later buried with the dirt we excavated for the hole. We hit bedrock at 6' and couldn't go deeper.

Inside shot. I'm knocking out the wooden plug for the exhaust pipe hole.

The door.

Another ceiling shot.
(My family thinks I'm nuts.)

A couple more points.

I have not had any problem with the ethylene from the apples causing the potatoes to sprout. Just keep them at opposite ends of the cellar.

To insure good ventilation, you will need to drill a hole at the base of the silo to insert the intake pipe. Cover with wire mesh to keep critters out. The exhaust pipe is an inverted U-shaped pipe coming out of the roof. The flow of wind creates a gentle, natural vacuum that causes the air to flow through.

Another tip: there are labour laws that require very generous trenches when working below grade. That means a bigger hole, more digging, more $$. Be discreet. 18" to 2 ft. is fine, unless your soil is sandy and liable to collapse.

very good point you raise about regulations.In most places well out in the country if you are a working farmer you can legally ignore the building inspector if you arer buildinmg a smallstructure for production use.An eight foot deep excavation could very easily get you killed in a cave in if the soli is sandy or a very fine loam .red clay of the sort we have ariound here is extremely stable and not at all likely to collapse unless the evcavation is really deep.

It can be a very worthwhile thing to be aworking farmer when it comes time to deal with all sorts of govt busybodies.

For instance I can legally ride my atv on the local public roads if conducting legitimate farm business such as checking fences,or going to prune my apple orchard which is half a mile away from our house.Legally she is a tractor when so used.

Even a minor accident can cost you hundreds of times what it would cost to hire a contractor with insurance to do a small job.Never cut corners on safety.

But the flip side of the safety coin is that a lot of potentially really dangerous jobs or activities are quite safe-IF you take your time and really know what you are doing.

Automobiles,ladders,wine,beer, whiskey,airplanes,sex,multistory houses,and fire would all be against the law if the safety nuts had been around and in charge way back when-the way they are now.

But the philosophy here seems to be to learn how to take care of yourself,because sometime soon there may not be anyone else to take care of you.

I have built a couple of root cellars, and know of quite a few others, so I hope you find my suggestions helpful.

First, unless you have a truely large amount of food you plan to put up (ie feeding many, many people) you don't need a very large space. A 6' by 6' should be more than big enough for a family of 4. (Think of a 50 pound sack of potatoes, which occupy a couple of cubic feet--and imagine how many of those sacks you can put in a bin 2' by 5' by 4'). My biggest was 6' by 6'. The smallest I made was just a 3' cube (this probably wouldn't work outside--it was located under a cabin in the Alaskan bush). I've also use 5 gallon buckets (see below).

A very simple (and cheap) construction would be to just dig a hole and roof it over with poles, a couple layers of visqueen and dirt. The dirt should be at least 2/3 of the frost level for your area (ie for here, with a frost level of 6', you'd want 4' of dirt on top). The problem is this probably would become unsafe after about 5-15 years as the poles rotted out--but if you did all the labor you could probably build it for $100.

A concrete silo would be really good, except the rounded areas would make it difficult to build shelving. Another possibility might be a short (10') piece of large diameter culvert (8')--with the same problems.

A concrete structure would be good, and would certainly be durable. You'd never have to worry about replacing it as long as it never froze inside (such freezing would likely make frost heaves, which can break concrete).

A very simple 'root cellar' can be made of a 5 gallon bucket down a 2' diameter shaft. Just cover over the shaft with a little insulation, and the shaft should probably be 3 times the frost depth (I've only used this to keep vegetables for a couple of months--ie October & November) here in Alaska.) One thing I tried that failed miserably was a sealed 5 gallon bucket under the ice. While it didn't freeze, everything molded really bad. Ventilation is critical!!

Since all of my (large) root cellars have been under cabins, I don't know how you would work the ventilation for an outside root cellar. I suspect even my bucket under water would have worked if I had been able to ventilate it properly.

Once set up and if controlled properly root cellars work really well. I once stored carrots (in dry sand, one degree above freezing) that were as fresh after 9 months as they were when they came out of the ground. I have an old book called "Putting Food By" that was great. Not sure if it is still in print.

As for your question about lost skills (like building root cellars), I suspect in our information rich society it wouldn't be too hard to come up with the information on doing things that were once common. The only problem I ever ran into along these lines is how to plant wheat by hand. Then I just had to experiment to get it right; now there are 100's of internet articles. But, with a lot of things like this, it isn't too hard to figure it out. It just takes time (3 years for my wheat problem--which occurred before the internet!)

I stayed on a farm in Holland for a couple of weeks. The vacant farm house was 1 story and it had a very small root cellar, basically stairs leading to 3x3ft area. It worked well. There was no frig in the house so we kept our milk and cheese there.

One thing about an outside root cellar in the north, what happens when you get a lot of snow? Will you have access? In the old days they must have built them with stone and cement by hand. Wouldn't that be cheaper?

Here is the entrance to the above root cellar.

It's a "storm-cellar" type entrance, with slanted doors. In the wintertime, a few sweeps of the shovel will make the snow fall to the side: the doors are quickly cleared, easy to open.

The root cellar is covered with a couple of feet of dirt. Plus Japanese Knotweed have completely covered the mound, further sheltering it from the sun (and prying eyes).

As far as building the root cellar from stone as you suggest, that takes a lot of time. Plus, it assumes that you have a big pile of stone that you would have accumulated from clearing your fields. Also, you need someone with expertise so that the stone roof is built in an arch, and will not collapse on you.

On the farm where I grew up there was a pit several feet deep that served as a cellar. No walls, no roof, just a pit. The house was destroyed by a tornado in 1941 so I've never seen it, but I'm told the pit was underneath the kitchen which had a trap door that opened up to the pit.