I would love to talk to someone with extreme cold climate issues and if a pit greenhouse is practical. My frostline is like 10'-12'down.I get temps as cold as -60F but usually about -30. I have good gravel soil about 2' down and watertable is 120' down. No south slope but several places where I get sun. I mostly want to be able to extend my season to about March-Oct. I am thinking of putting a lg rocket mass heater in. And some kind of geothermal fresh air vent. Any ideas or someone else doing this I can talk to?

what latitude are you located in?

I used to live in upper MI and it froze down 8 foot there sometimes. I dont know how it would be done, but there are members here to have walipinis in the rocky mountains where its much colder. perhaps they'll chime in soon, but they'll want to know your latitude too.

im building a walipini but im at 35 degrees latitude and our coldest around here is 0 to 20 and thats only for limited periods.

Dear Julie,

We have a solar growhole-type thing. It's built of 8" concrete blocks, which are filled with concrete. This past season I insulated the beds from the outside walls, and that seems to help, BUT the big deal seems to be that, once the soil temperature drops below a certain point, growth just stops.... Our glazing is 4 mil plastic, and none too tight, either. Soon as the spring crops are done in there, and the garden is going good, I want to excavate the soil out of the beds and install some bottom heat. I am convinced that bottom heat is the only way to really grow stuff over the winter, vs, just "hold" it.

I rather suspect your situation will prove similar.....

Best, TM

I am on the 64 Lat in AK. Our frost line is 10'-12' down. I am thinking I will insulate the outside walls and out from it about 4' (wings) Probably start with poly top and bottom of rafters then later as money allows use double walled poly panels. Probably will insulate the bottoms of the grow beds or use elevated beds. also a cold sink and a RMH. Mostly want to use it from about March or April on... Thanks, Julie

BTW, Paul, Kinch says, Hi! I work with him and we had a nice chat about all this, And going out this summer to collect clay... I know the CD"s will probably answer this but I have to wait a bit to buy them... What do you measure FIRST to get your CSA? The heat riser? So if I use an 8" square brick riser, then all the other areas need to be the same sq. inches of air movement or larger. (64 sq. inches) Also just how much build up are people really getting with long term use? Thinking about making a curved bench so thinking of using 3 or 4 tunnels of metal dryer venting with cob around for support and mass and strength. But The clean out might be an issue... non smooth interior...

Julie, do you live around Fairbanks or somewhere else along the 64th parallel? I lived in North Pole from 91-94 and had some interesting times with gardening. I tried raised beds and all sorts of things to get the ground warmed up enough in "spring" to get my stuff going. We settled on starting everything in pots and trays and then using clear plastic to provide a greenhouse effect to make the best use of the sunlight in our patch of black spruce forest.

The ground around there doesn't really thaw farther than 4 feet or so down, before it freezes back up again, that whole permafrost thing. There used to be a house on the east end of Farmer's Loop that was a called the Permafrost House and showed the dangers when building a deep basement structure there. They'd done all kinds of stuff to try and stabilize the permafrost under it so it would be habitable, but I think that they finally gave up at one point after the "heat radiators" thing only partially stabilized it. I also remember all the heat radiators along the pipeline did work and were used to keep the ground under the footings frozen to minimize frost heaves moving them and damaging the pipeline itself.

I said all of that, not to discourage you, but to point out some of the issues you can face with doing heating projects on permafrost. I believe that if you were to hyperinsulate your pit and walls, then fill back in with your soil mix you could be successful. Using the sun to your advantage and warm the place up. As long as you isolate the base of your cob from the raw ground it shouldn't disappear on you. This is all postulation on my part as we only ran our garden from June to September while we were there. Plus my thoughts about permafrost may have more to do with deep excavation and concrete than mild excavation and soil. We had good success with cold hardy crops (Yukon Golds, peas, beans, leafy vegetables, broccoli and cauliflower) and none at all with anything from warmer climes. If it wasn't for having our roots in Montana, the Bride and I would have gladly gone back to the Interior.

Delta Junction, Where we are we don't have permafrost. But I agree about the insulation. Just would like to see if anyone else has done this pit greenhouse in such a cold place and what other issues I may run into...Thanks!

Julie, You may want to take a look at a Rodale Press book, "The Solar Greenhouse." Our copy is around 35 years old, but has some great information. Hopefully they've updated it by now....

Best, TM

So still in the Black Spruce, but not on the bog with the permafrost! Always enjoyed my visits to Delta. Maybe instead of going down, you might want to think about going up. I'm figuring going down would basically make for a cold sink and you'd always be fighting that characteristic of it, where if you go up with a HugelBed or more and then put some cover on it or stretch cover between it and create a sun scoop with plastic roof instead of a linear line. That kind of thing I did do a bit of off the south side of our house. It worked pretty good, although it did use the heat mass of the house to provide some of the thermal load. I think I said that right.
Anyway, think of sun scoops either on level or slightly above instead of going into the ground. I'm pretty sure I read somewhere on here that one of the benefits of Hugelkultur is that it pulls your plants out of the ground frost plane - which I am taking it is your goal.

Thanks for those ideas. Growing up up n down the west coast (lower 48 ) I didn't know a ugly tree til we came here among all this Black Spruce! Lol I love all the Birch though! So its a trade off. One reason I was thinking of going down was we have bad wind issues here. Often,gusty and strong. I will check out the ideas you mentioned. I found a source for free used fire bricks so one way or another I am gonna at least build my cob oven if not a RMH!

Juilie: Don't delay, Start planning your RMH ! I built mine in the greenhouse last summer and have been amazed at the difference !!! Previously we used 12-15 cord and had to keep a fire going 24 -7 to hope to keep it above freezing and it was always to hot or to cold and the plants were Not Happy! This winter I have used apx 5 cord and the coldest it has gotten was 41 ! No fire all night long !! How cool is that ! The room is evenly heated now instead of hot near the stove and cold everywhere the plants are, its an even temp thru the whole greenhouse! I'm at latitude 47 and get nowhere near your temps but I can't recommend anything as much as a rmh in a greenhouse they really do the job.

Julie Norris wrote:Thanks for those ideas. Growing up up n down the west coast (lower 48 ) I didn't know a ugly tree til we came here among all this Black Spruce! Lol I love all the Birch though! So its a trade off. One reason I was thinking of going down was we have bad wind issues here. Often,gusty and strong. I will check out the ideas you mentioned. I found a source for free used fire bricks so one way or another I am gonna at least build my cob oven if not a RMH!

I was actually thinking about this and remembered you guys have that nice wind tunnel through the pass - and that might be why you wanted to go into the ground. Thomas makes a good point on his RMH for the greenhouse. If it only got down to 41 all winter and we had more than a couple days where it was -25 or lower around here. My favorite ice fishing lake got down -41F the same night we had -26F. I'm glad you aren't walking away from the RMH idea, whether it is "just" a cob oven or a heat source for your walipini/pit greenhouse. The use of HugelBeds could still be a potential wind break point as well.
I miss the birches that we used to camp under out at Quartz and Lost Lake. Lots of good fishing.

Yeah, wow. We heat with greenhouses because though our winter is reasonably cold, we get plenty of sun at 34 degrees north. Hearing your situation, phew! Obviously you won't be using the sun as a heat source in the middle of winter.

I think you'll need:

• To insulate from both the outside air and the ground. You may want to have insulated curtains for night that you operate in the coldest part of the year. In Tibet I saw whole fields covered with hoop tunnel greenhouses (run by Chinese farmers); They were selling green peppers, cauliflower and eggplants in February. They had made quilts out of plastic tarps with something stuffed inside (I would stuff plastic garbage) that they threw over the outside of the greenhouses during winter nights. There was almost no snow there, but that could be an issue in Alaska, and I don't know why wind wasn't a problem. Interior curtains avoid snow and wind problems, but are hard to keep pressed up against the glazing; these external curtains were absolutely low tech, just thrown over by hand. Ground insulation is more standard on these forums and in Alaska, so I think you'll get plenty of good advice.

• Some kind of heating inside the greenhouse. Plants will stop growing below a certain temperature, but also below a certain amount of light per day. Our experience here where we provide no extra heat or light except the passive sun, is that hardier types of plants can sprout and grow in Nov-Dec, then don't really make progress in Jan, but as soon as the greenhouses start warming up in Feb, the plants take off, and we can start harvesting large amounts in mid or late Feb. For us the most successful winter plants have been chard and some kind of local mustard greens. These don't mind a degree or three of frost, they just hunker down and wait. I'm sure there are many others just as good. But we do get a reasonable day length all winter; I don't know what difference that will make. We don't try to keep hot season vegetables like cauliflower and green peppers going into the winter.

• Thermal mass inside the insulated envelope, especially if you have an intermittent heat source such as a manually fed rocket stove.

I will be insulating and maybe adding mass to all but south wall and Hubby was talking about doing a solid type outside shutter that would lift up during day but I would like to figure out an internal system. (snow, wind...) I will insulate the ground also and use elevated beds... mostly I am really not trying to grow in winter just be able t get spring stuff growing early enough to have it ready when summer decides to stop by...It is kind of funny how I used to be bothered by the things I had to forgo or work to grow when we lived in zone 5/6 now that sounds SO great when limited to zone 2! But the nice thing about here is that god generously planted tons of wild strawberries,blueberries, and cranberries for us to go pick! Couldn't do that in NM!!! Do miss the heat of the sun in winter that we got there though! Picked up a couple old glass stove doors for use with my RMH to make it a kind of "fireplace" can't wait for spring!!!

Take what this guy says and apply it to greenhouses

http://www.hearth.com/talk/threads/energy-efficient-house-building-in-fairbanks-alaska.122044/

Don't forget the 22000 liter water tank for thermal banking.

The chinese greenhouses look effective. It's long instead of rectangular. I have a hypothesis. Put a wall up splitting the north and south. Chop up some poplar and inoculate with mycelium. Hoist it up on the north side so that it is exposed to the oxygenated air. It will make CO2.

Also use the masonry fireplace. I have another hypothesis, it's probably flawed, so wait for someone that knows better to comment. Make it to code but put in a valve to vent the CO2 into the plants just before it exits the building. The masonry fireplace is highly efficient and I'm thinking the air is going to be clean of pollutants.

Yes, we really like what Thorsten Chlupp is doing in Fairbanks! Would love to have his resources!!! Am planning on using a lg water tank but not sure I can do a 5000 gal one like he has! As far as the other idea I guess I need to look up some pictures. ( I am such a visual aid type! Thanks!!

Julie, where in Delta Junction are you? We lived there from the late '50's until 1967 (and Dad was there for a few years after that, then moved back to Tok where he lived until he died a few years ago). We had a homestead on Clearwater Lake. Mom had a pretty good-sized vegetable garden -- I think someone has built a house on it now. And Dad and Grandpa raised potatoes and were partners in a dairy.

Kathleen

We are off Jack Warren. Spring breakup is in full force,killed my first mosquito today,ugh!

Julie Norris wrote:We are off Jack Warren. Spring breakup is in full force,killed my first mosquito today,ugh!

Julie, do you know where Fales Road is? That was the road back to our homestead originally! I think they've straightened it, but last time I was there, you could still see the road Dad pushed in with a small cat.

Kathleen

I enjoy reading everyone's enthusiasm and ingenuity on growing food in the winter, but I am also wondering why a person would not move to a less harsh climate, especially if one wants to grow their own food.
Keep plugging away at your dreams. I'm definitely learning things about self sufficiency.

Hi Chuck; I think there are several reasons for some of us choose to live in harsh or remote climate's.  One is the heat down south . I personally do very bad as the humidity climbs. I don't like high heat much ether but at -20% it is bearable. Another is the solitude, if it was nice all the time it would be flooded with people... Another is some of us like winter, however we like eating fresh greens as well hence a rocket mass heater in our greenhouse!  Crowds of people make me jumpy, massive traffic jams make me understand road rage...  Here in nw montana if there is a line of more than 3 cars on the road its bedlam ! More normal is 60 miles without seeing another vehicle just  dodging deer ,elk and bighorn sheep on the road THAT I can handle !  If we lived down south with the crowd's  of people we would have to lock our doors ! Patrol our garden to keep scavengers (4 footed and 2 footed) out. Drive thru millions of people just to get anyplace. Never get to enjoy the northern lights streaming across the sky,  never listen to a bull elk bugling his superiority  or listen to the wolves howl. There is something primal about making your own space in the wilderness and creating a home.