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We bought an old farm house and property. On the property is an old quonset hut dug in about 4'-5' deep. It was used previously as a spud cellar but for years has collected junk.

I'd like to convert it to a greenhouse. It's 80' long x 30' wide and about 12' high.

I would like to grow tomatoes and peppers in the winter but east Idaho winters get very cold.

I don't want to spend a fortune heating the thing. What alternatives or options do I have to traditional heating systems that will keep the greenhouse warm enough during the cold winter to grow tomatoes and peppers?
 

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We bought an old farm house and property. On the property is an old quonset hut dug in about 4'-5' deep. It was used previously as a spud cellar but for years has collected junk.

I'd like to convert it to a greenhouse. It's 80' long x 30' wide and about 12' high.
Not real sure how you would convert it. Most quonset huts I've seen don't have a frame as such.....the metal IS the frame and the roofing/siding at the same time. Looks like you'd basically have to start over with a frame of some kind and cover that with something that lets light in (plastic, polycarbonate panels, etc)


I would like to grow tomatoes and peppers in the winter but east Idaho winters get very cold.

I don't want to spend a fortune heating the thing. What alternatives or options do I have to traditional heating systems that will keep the greenhouse warm enough during the cold winter to grow tomatoes and peppers?

Another thing to note...it's not JUST the heat. I have a small greenhouse, very well insulated (built into the mountain on the north side, south side is triple wall polycarbonate panels for glazing), and we have tried to raise tomatoes here (Tennessee) in the dead of winter. What we find is that DAY LIGHT is as big an issue to production as heat. I could keep the heat up (maybe fall to 50 at night, with daytimes well into the 80's), but the lack of hours of sunshine is something you can't get around unless you plan to also artificially light it. The plants simply "know" it's winter, and while they will grow, they just don't produce a lot.

What we have since concluded is it is better to have LATE tomatoes by going into late fall with plants nearly mature and bearing, then start plants again about February for EARLY producing.....say 2 months ahead of outside garden raised. Haven't tried peppers, so I don't know on them, but suspect you'll find similar results.

On heating:

Insulating and design is going to be a huge factor. As I said, we have a small (12x20) greenhouse I built back into the mountain. The north side (20') and east side are almost completely underground. The south side has a 30" raised bed on the outside as an earth berm. I used triple wall rigid polycarbonate panels for the south facing cover. Typically, it will stay above freezing (barely) on a 10 degree night with no auxiliary heat.

We also built a 20x36 hoop house last fall. 30" tall raised beds around 3 walls, single layer of greenhouse plastic sides/top. It will only stay about 5 degrees above outside temps. This year, I poured the center floor with concrete and built a 5'x20' raised bed down the center. Put 3/4" pex floor heating tubing in the concrete, the center bed, and part way around the outside beds. I currently installing a solar water heating system that will run hot water in that pex tubing, and hopefully keep the inside above freezing this winter. We use it to mostly raise cool weather stuff ( broccoli, cabbage, carrots, lettuce, etc), so it doesn't need a lot of heat....just to stay above freezing. I may also add a second layer of plastic to the top with an air inflation fan.....waiting to see how the hot water system does as of right now.

You could do something similar. IF I were building it from the get-go with hot water heat in mind, I'd dig down about 2-4' (depending on whether I planned to have raised beds or not) and put at least a couple inches of rigid foam so my heat wouldn't bleed out. Run a LOT of tubing, then use either solar or a wood boiler to heat my water ( or a combination ). In your climate, a double layer of plastic for sure....or maybe go with Solex, which is a flexible, double wall version of polycarbonate panels...comes in 4' and 6' wide rolls, or go with rigid polycarbonate panels, triple wall ( but get ready for sticker shock ! )
 

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Unsure if this is an option for you. I'm experimenting with 'off the grid' greenhouse. I've insulated (double plastic walls with air space), set up rows of gallon water bottles (gather heat during the day) & presently building to movable solar can convection heaters (inspired from instructables.com). Hopefully I'll be able to grow winter crops through the winter.
Re: tomatoes. Unless you have lights, heat to 70 + degrees, everything I'm reading is stating this is near to impossible to do.
Please post info if you find a source that is doing this (growing tomatoes/hot weather plants) in winter with success.
 

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Heating is almost always more expensive and energy-consuming than cooling in a greenhouse, unfortunately.

TnAndy's idea is a good start - the concept is technically known as 'thermal mass.' the idea is to incorporate a dense heat sink that will collect heat from the environment throughout the day, then release it at night when it reaches its max absorption capacity. The thrmal mass can be a masonry wall in the north end of the greenhouse, or barrels of water like Andy suggested - (personally, i don't think that is a responsible use of water, though). This can be supplemented by changing the ground cover to something like gravel that will absorb sunlight during the day and release it at night, as well.

As far as systems go, you could consider hooking up a water heater to buried lines - it is more expensive up front, but best for most long run applications; you could also hook up a nat gas greenhouse heater to some tanks that you'd have to keep refilled. Also consider adding blanketing that can be pulled over at the end of the day to trap heat through the night.
 

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Thanks, all, for your thoughts. I'm new to the forum and not sure how to use it to do the nifty quote things you all do, so please bear with me. :)

TnAndy - The spud cellar has a wood frame that appears to be in good shape. I had a guy out to give me an estimate on putting a greenhouse roof on and he was surprised and impressed that the frame ribs were the exact distance apart as the panels he sold/installed (coincidence? ;) ). I've also been doing some research on the water heating and pipes thing you mentioned. It seems if I have a big enough compost pile I can use that to heat the water and then pipe it in the greenhouse. I still have some research to do but that's the direction I'm thinking now. Thanks for the suggestions regarding piping water. We will have to have lighting too, but that is a smaller concern to me than keeping the place warm.

Janis - that is fascinating. I wonder if I could replicate it on a much larger scale...

Backyardcreek - the lighting and heating to 70+ degrees is what I'd like to do... a tall order for Idaho winters where it is not uncommon for it to be -20 at times. This guy in Canada has a greenhouse that seems to stay pretty warm (I wonder if having the animals inside is a big contributor). Sorry about the poor quality video, I can't find a higher quality one on youtube:
[ame]https://www.youtube.com/watch?v=UluPey05VEQ[/ame]

Tyler520 - I wonder if I bury a steel drum in a very large compost pile and use that as a water heater and connect it to lines that would run through the greenhouse if that would help. I also wonder if I can make some kind of radiant heat system from that idea...hmm... I like the idea of blanketing. I'll have to look more into it.

Here is a video I found regarding using a compost pile to generate heat (anyone here try it?):
http://compostpower.org/node/24

It almost looks too simple and easy that I must clearly be missing something.
 

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compost heating has been around a while - I know lots of people who bury compost or peat under the root systems of their winter crops so that the heat from the decomposition will warm the plants through the season.

it is an interesting idea, but I would be a bit leery - greenhouses are very prone to pests as it is because it is a tightly controlled system in a tiny space. Putting compost so close to your greenhouse could make pest management a nightmare.

Also would require a lot of labor - you'd have to decide if the manual labor is better for you than a more hi-tech system that requires less input.

Might be worth biting the bullet and getting a small dedicated PV or solar water heating system just for the radiant heating system.
 

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As mentioned previously, the need to heat to above 55° at night and the lack of light during the winter are going to be a problem growing warmth and light loving plants like tomatoes and peppers.

What people up north with greenhouses in the winter is to grow all sorts of greens and cole crops (broccoli and the like). Check out Eliot Coleman's books.
 

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First you don't grow tomatoes in the winter. Heat isn't the issue.
light is the reason it doesn't pay. Tomatoes need Par 20+ to set fruit. In winter in most locations in north america your getting PAR 10. About 50% of the light you need. Even using super intense led grow lights which cost 800 dollars each. It would cost near 15 kw hours a day for a 8x8 space. that's about 2 dollars a day. 60 a month.... with led's. Using "cheaper" standard grow bulbs it would cost near 200 a month for electric. But on a good note it will lower your heating cost.

Now you want tomatoes in winter? There is a way.

Plant your tomatoes in starter trays at the end of December to very early Jan. You pay for some light but it's not too bad because your not making fruit. After your sun hours go above 10 you can limit light to very cloudy days. :) It will take them 8 weeks to be ready to be planted "out" in the greenhouse. So around march 1st you plant them in the greenhouse. They will begin to fruit in mid-late April if you provided good nutrient and warmth... May if you had issues. Tie up and lower your indeterminate plants and keep the harvest going. The plants will produce till October easy... Adding some light come mid-late November will ripen the last of the bunch in mid December. Get a long keeper variety. They will keep 6-8 weeks. That means your good till February. :)
 

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We "grow" tomatoes and peppers all winter. Start in July, reset to large tree pot, they set fruit, move inside before frost, they ripen all winter. Start plants in Jan, plant in large tree pots in March, put out to harden off late March, in and out of garage (south facing door) until frost is over, ready in July. I do use a grow light in the greenhouse. 2 tomatoes, 2 peppers....James
 
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