Greenhouse construction

[sjambok]

Planning to grow food year round. Wanted to know two things:

1) Materials and a way to build a greenhouse so it isn't felled by high winds.
2) would greenhouses be compromised by snow loads?

[rambler]

Plants need sunlight, so in northern climates like mine, it gets difficult to grow over the winter - not enough sunlight. As well, heating becomes crazy expensive.

Glass was the typical greenhouse.

If you are looking to extend the growing season, hoop buildings with clear plastic can add a couple months. Can be a commercial building frame, or as simple as a few cattle pannels bent in a U and tee posts to hold them down.

FarmTek has some interesting poly (plastic) paned greenhouses, typically small for a small family. At least worth looking at for ideas. They also have the plastic film type that are bigger - they are on the web, check them out.

Snow loads can be hard on any building, including greenhouses.

--->Paul

[TnAndy]

Well, I assume since snow is a concern, you live in an area that gets fairly cold, huh ? (I'm always amazed people ask area specific questions, but don't fill in the location part of their profile )

Personally, I would NOT build a 'conventional' greenhouse for anything other than cool weather crops, like lettuce, spinach, cabbage, etc. The cost or effort ( assuming you used wood stove ) of heating it will be HUGE.

We earth bermed ours. On the north side, it is almost all underground, the south side ( front ) has a 30" tall x 24" deep berm that doubles as a permanent strawberry bed, and the east side tapers from the north side down to the south berm. Only the west side is earth free, for an access door. It's 26 here this morning, and the greenhouse temp is 58 inside with no heat on.

The next thing I would do ( and did ) was build a decent roof structure ( I used treated 2x6's 24"oc ), then I'd use triple wall 16mm polycarbonate panels for my glazing.

You can plan to pay PLENTY for them, but it beats dual plastic that you have to keep an inflation fan running 24/7 plus replace the plastic every 4 yrs, or actual glass, which is way less energy efficient, harder to seal, and heavy.








And lastly, you need to decide WHAT is worth growing, and when. We use ours mostly to get an early start on spring seedlings....but we do grow some tomatoes year round. A good variety to try are Siberia.....they will set fruit down to 39 degrees is what I read, so you can grow them in far harsher conditions than most any conventional variety.

[Windy in Kansas]

Originally Posted by sjambok

Planning to grow food year round. Wanted to know two things:

1) Materials and a way to build a greenhouse so it isn't felled by high winds.
2) would greenhouses be compromised by snow loads?

Snow load is a very big factor in greenhouse engineering.

May I inquire as to how you will heat the greenhouse and ventilate it? It isn't unusual for both to be needed on the same day.

[Paul Wheaton]

Check out this book:



The Earth Sheltered Solar Greenhouse Book


I went to the author's place and video-ed his greenhouse. The main idea is to minimize the total air under the glass and to make a deep trench toward the front. He was able to keep tomatoes in north idaho until mid december without additional heat.

Here is a video of it:

http://www.youtube.com/paulwheaton12#p/u/44/-hV8Teiskfo

And if you wanna add a rocket mass heater, here is a video of an oehler style greenhouse getting a rocket mass heater added to it:

http://www.youtube.com/paulwheaton12#p/u/39/qtFvdMk3eLM

I visit a lot of farms and I see a lot of abandoned greenhouses. And on at least two occasions I have been there just before they state to build the greenhouse and I advised them to not build it .... there .... in the winter shade ... where they have staked it out. And both times they ignored me. I know one of the greenhouses got taken out. I suspect the other eventually will too. What's the point of a greenhouse in the shade?

There are a lot of issues to be aware of with greenhouses, so i started this thread on the downsides of greenhouses.

[Wolf mom]

Here's another book:

The Solar Greenhouse Book by James C. McCullagh. First part goes into glazing, regioinal considerations, orientation, including solar charts, etc. Then construction, and last managment & regional gardening.

I took a greenhouse class by a professor at Northern Arizona University - 7000 feet with lots of snow. (they do high altitude training there) He recommened this book last year. I got it on Amazon for a few dollars & highly recommend it.

[MaineFarmMom]

Are you sure you want a greenhouse? It's not practical in MN. Are you interested in a high tunnel instead?

[Rusty'sDog]

An often overlooked problem for green houses is that you are creating a Spring environment in Winter. If you have created an ideal growing environment for your tomatoes, you have also provided it for the bugs and pathogens that want to consume your plants. Open your doors in the spring, and they are ready to attack whatever you plant outside. You have created year-round problems if you have not controlled them all winter.

[cc-rider]

TN Andy...
Beautiful greenhouse. Can I ask a couple questions?? What is the depth of the greenhouse? The construction pictures make it look narrow, but the inside pictures look spacious. Also, what is the purpose of the strawberry bed being so high? Is it to protect the south side of the greenhouse? Could you have extended the glass down to the ground and done away with it, or does it help keep the temperature more stable inside?

[TnAndy]

What is the depth of the greenhouse?

12' wide, 24' long on the glazed part....small section of roof on the far end for storage, and a small section other end that is closed off from the greenhouse, and contains the electrical gear ( inverters, charge controllers, battery bank ) for my solar arrays.

Also, what is the purpose of the strawberry bed being so high?

One, since we knew we were going to use home made benches inside, waist level, to extend the glazing on below the bench was simply a waste of material.

Two, since that 'kneewall' was going to be up 32", ( four cinder block high, also the level of the inside benches ), it was either insulate the whiz out of it, or put a raised bed out there to act as insulation.....I picked that option. The front of the raised bed is 3 cinder block + one cap block high ( 28" ), so the bed slopes 4" in it's 24" depth.

Three, a raised bed of something permanent like strawberries made the most sense, then they don't grow high enough to shade the glazing, and standing there weeding/picking/working a bed of that height makes life a WHOLE lot easier than stooping over or getting down on your knees when you get up to our age. ( you'll find out )

[Oldcountryboy]

Just how big of a greenhouse are you wanting? Have you considered cold frames?

I just read a article in a old magazine of Countryside about this guy who has a 20' X 96' long cold frame. He claims he can raise a garden yearround inside his. He has 2 sheets of plastic over it with a fan inserted into the bottom sheet that keep air between the 2. This insulates it. Then at the inside front of the cold frame he has two chicken pens on each side that he keeps chickens in. He doesn't say how many but says there purpose is for the body heat they produce, which keeps frost off his plants, and they create just the right about of Carbon Menoxide/Dyoxide ??????(Don't know my chemisty)for the tomaotes. Also feeds the garden waste to them which creates fertilizer. In the center walkway he has a buried worm bin that he feeds chicken and garden waste to and in turn the worms create worm casting which is great for the garden and he feeds worms to the chickens also.

I've got a 15' X 96' cold frame up but I don't have the plastic on it yet. I bought mine several years ago from a company called Crop King. It was kind of pricey but it is well made. I don't think I have to worry about major snow damage, especially since the most we usually get is 12 inches. Our average snow fall is only about 3 or 4 inches.