I know there are some cold frame fans here, Grubbyknees . . .

Personally, I went from working a range of 150' by 50' greenhouses to a cold frame. I just couldn't adjust to the lower air volume! My advice is to check the cold frame thermometer often thru the day no matter what the weather. And, build them with as much air space as you can.

I've successfully used little plastic "hoopies" in the garden. Nothing more than re-bar driven into the ground, 1/2 inch pvc pipe arched across a 4' bed, the arches covered with 6 mil plastic film, and the whole thing held down with baling twine, wood stakes, and bricks. There's usually one or 2 of these things that spring up in my yard like mushrooms each year.

The next step up is a 10' by 20' tunnel made essentially the same way. A center path was excavated to about 18 inches so the 15' pvc pipe arches are high enuf to accommodate the gardener. The 6 mil plastic goes on and off each Spring. Something of a bother but I've got lots of room for starting veggies in the beds and for "spill-over" from a 9' by 20' greenhouse.

I've got photo's of the tunnel if you'd think that would help but the humble hoopies haven't been "immortalized" in a picture yet.

digitS'

Wait! Someone else has a picture on the 'net. I think they've run the twine directly across and tied to the arches from the looks of it. I don't do that - drive addition rebar at the 4 corners and criss-cross the twine. Additionally and at the very least, the gathered ends have bricks piled on 'em. All that in the interest of not allowing the wind to carry 'em away.

Here is a link that might be useful: hoopie

Thanks, I had thought about hoop houses, but wondered how they fare in the wind.
I will probably do a row or two of hoops, but I would really love a grow box that has a lid. I want it to be fairly easy to harvest salad greens each evening without wrestling with plastic.
I was thinking about using sheets of clear corrigated fiberglass for the lid? They come in 8 foot by 2 ft sheets.
I have basic tools and bit better than beginner skills. I just need a plan.

There were a couple of threads last season about cold frames that might help. Maybe someday I'll get around to building one of my own.

Here is a link that might be useful: Extending our season thread

thanks!
I have some rebar. what do you use to cut it in sections?

A hacksaw - then bend, and break 'em. Rebar metal isn't very hard to cut or break.

18" is enuf to anchor each end of a pvc pipe. You aren't really trying to hold things down with those - just holding the hoop in place.

I drive longer rebar at an angle at the 4 corners and tie baling twine to them for the criss-crossing over the film. Don't leave those bars much out of the ground or they'll be tripping hazards.

S'

So THAT's how you cut rebar! the stuff looks so tough. thanks.

I want to do some serious season extending next year. I want to try hoop tunnels, cold frames-whatever. I'm going bonkers trying to garden here.
Ok, I know this sounds ugly, but I have 3 acres to hide it on.. Has anyone taken a dead refrigerator, laid it on it's back and buried it 3/4 deep. Put dirt in it, a plastic cover for daytime, then closed the door at night?
It's an insulated box. It has a door and people are thrilled to have one hauled away. Am I crazy, or does that sound like a pretty good, really easy cold frame? Not to mention cheap.
what do you think?

I don't know if that would be a good idea, I'd be worried about contaminating the ground. I've built a hoop house here in Cheyenne with cattle panels, but it's backed by the garage and a few feet from a privacy fence, simple windbreaks. Your refridgerater idea did put me in mind of something I'd like to try if I owned the right space, a below ground green house/ hoop house. Lost the link but the idea is you dig a hole in the ground a few feet deep and use that as your growing space. Kinda like a walk in cold frame, with stairs going down into the growing space. It seems like the plants were about 2-3' below ground level, with a walking space 2-3' deeper. Thus the plants were below the ground freezing line, but close enough to the surface for sunlight. It seems like the hoop stood about 3' above the ground. I think the low profile helps against the wind, I had a friend whose greenhouse was actually moved a few feet by the wind.

I have a plan for a "greenhouse" a lot like that! I haven't looked at it in a while but, you dig a trench with steps at one end. Build a simple top over it with Southern glazing and garden on the ground level. Or maybe the planting level is a bit lower. I'll have to look for the plans. I thought it was a neat idea.

My soil is pure sand. I feared cave-ins with that idea. I really like the elegance of it though.

I've seen more ambitious underground greenhouse plans. They are very appealing in this climate.(Casper).

What if I had the freon removed from the fridge? Do you think it would work?

The freon, I guess, would go straight up in the air and that might be what happens to it with all our old refrigerators - don't know.

The Pankar-huyu greenhouses, as recommended by BYU, may be of help. They remind me of a greenhouse featured in Organic Gardening many years ago. Those were built in China & I used to sit and wonder if they'd be of help for me. The floor of that little pit greenhouse is on 2 levels - the "growing bench" half is higher than the path area and more directly in the sunlight. Since it is in the ground, a shadow falls across one-half the floor (the path) even during mid-day.

I finally decided that I wasn't going to gain that much space from all the digging work. The angle of the sun is fairly acute from up here near 49° and the ground is cold.

I once was often in and out of an old commercial greenhouse - part of which was semi-subterranean. Strange little structure - it was like a greenhouse roof sitting on the ground. The path thru this narrow building was about 3 feet below grade so the growing beds were at table height. The grower used gravel for improved drainage and had potted plants on the gravel.

You can do a google search of "pit greenhouses" and here's some info on hobby greenhouses from Canada with something on those pit critters. It also has simple plans for cold frames and hotbeds and, altho' a pdf file, doesn't take too long to download.

My big(ger) tunnel has an excavated path which I believe helps with heat retention and also permits a low profile of about 5 feet to cut down on exposure. I think you can take this too far, however. If the soil is only 45° or 50° and if very much of it is exposed by excavation, you may have some trouble getting the temperature in there above that level on any but the sunny days. That might not be much of a problem elsewhere but I have to deal with lots of cloudy Spring days here. Lots of things won't grow well unless the air temp stays above 60°.

Steve

See if this helps. It is an article on grow boxes from the cooperative extension office at the University of Wyo.
https://ces.uwyo.edu/PUBS/B1151.pdf

Here is a link that might be useful: Grow Boxes and Hoop Houses - UW CES

Ah, I thought I'd read this thread before -- it's from 2007-8. Deja vu! :)

Another idea that might be useful is hay bale cold frame:

General concept:
http://www.groovygreen.com/groove/?p=578

Larger and more ambitious:
http://www.energyfarms.net/node/1501

Up in the mountains:
http://www.motherearthnews.com/Organic-Gardening/2003-12-01/My-Rocky-Mountain-Winter-Garden.aspx

I have a fantasy of terracing a slope high in the mountains. Covering these terraces with UV-resistant plastic would raise the interior temperatures to extend the growing season.

Of course, the covering would need to be of an adequate height to allow me to move about within my mountain-hugging, protected environment. I would spend a good deal of time there since controlling the interior temperature would require nearly constant monitoring. A small pond would make a lovely distraction. IÂm sure that cloudy days and even the evening darkness would be very pleasant.

Instead of a continuing aging, this environment should alter the effects of the passing years. Perhaps it would put the gears of time into a reverse evolution, I would begin to grow webs between the digitS' and become an amphibian â«.

S'

And, this Saturday, we are going to the recycled construction materials place to pick out a window for my new cold frame! The one I haven't planned or built yet!!

J.

Here is a link that might be useful: Old Window Cold Frame

I'm with you jclepine. I have one in my mind and trying to make it work. I have a shower door made out of poly about 5' long and 20" wide going to be my top. The sides will be vinyl soffit to make it light and easy to move. Put some insulation board in between the board frame. Build a box with the back higher than the front so water and snow doesnt sit. I checked harbor freight and they have a vent that opens and closes as the temp fluctuates to open this shower door rig I have in mind.
Wife would rather me build stuff like this than be at the bar.

Hey, your not alone, I have been promised that the greenhouse will be put together before March for three Marches now. Maybe next March?? (We have all the material just sitting begging to be put together.)

And my cold frames, well they are waiting for the greenhouse to go up cuz I wanted to put them around it to share heat.

Billie

This is my first year starting seeds indoors. I have always planted directly in the ground or in 6 packs once it was safe to leave them outside. If my seed starting goes well, I'm looking at making a cold frame similar to the one in this link. I'm hesitant to buy this one because there is only 1 review on Amazon and it is pretty flimsy and the seller reviews on Walmart are not that great. But the design is what I'm looking for. I was looking at 4 shelf greenhouses but they don't handle wind well. This would mainly be for hardening plants in the spring. Made 4' long it would be the perfect size to fit right against the bottom of my porch. I could even screw the 2x4's into the porch support posts to secure it. I'm wondering if I can use plexiglas for the top, sides and front? Or for this year, instead of spending a lot, I could use heavy duty plastic and then get the plexiglas later.

Here is a link that might be useful: Picture of Cold frame

The coldframe in your link is kind of small. It won't hold that many plants. If you're somewhat handy you can certainly build your own coldframe. I'm building my 2nd coldframe this week out of a glass door that I picked up off of craigslist. Plexiglass certainly is not cheap and I tried some plastic recently but it's much too hard to work with on a daily basis. So I recommend finding a good glass door or window with a wood or metal frame and building the frame around the door or window you can find.

Here is a link that might be useful:

Thanks for the picture. I only have about 52" to work with in the spot I was going to put it. I was going to make the back 3' tall and the front about 1'. I'm not going to be planting in the ground so I was just planning on putting it on some cinder blocks or patio stones to have it raised off the ground. It would probably only have 4 flats in it at one time. I will look on craigslist and freecycle for a couple windows and think about a different spot where i can go a little bigger. Thanks.

Don't know much about cold frames ~ I have a triple pane window that broke its seal and is kind of 'foggy' ~ would that work ok? Is the glass mostly to hold heat?

Here is a link that might be useful: Help Around the Yard

The glass is mostly to admit light, AliceMae.

The greenhouse industry has done a great deal of research on glazing materials that best allow light penetration. Heat retention is important and especially so in a cold frame or unheated greenhouse. Still, plants use photosynthesis for growth.

Without sunlight, growth is entirely on energy and nutrient reserves. Commonly, that is called "stretching."

Steve

The glass will hold heat at night. A few cold nights I've thrown out a sleeping bag on top of the glass. Most days I open the top all the way to let the maximum sunshine and then close it around sunset. A triple window will hold a lot of heat in at night. The moisture between the panes will somewhat limit the light entering on the cold days but it should work just fine overall.