Years ago, I designed a greenhouse made of cattle panels. I'd tried to build one from pvc pipe, but it was just too flimsy. I saw pictures of someone's greenhouse made of cattle panels they had attached to the tops of t-posts they'd driven in the ground and that gave me an idea. Why not make one like that, but portable? Or atleast moveable without having to dismantle the entire thing.
I built a small 9'x20' greenhouse using a box frame on the ground to hold the cattle panels, and plywood on the ends to close it in. I spent a couple happy years in that g'house, but decided I wanted something a bit taller. So designed this one:
It's 7' tall, 10' wide and 20' long, and strong enough to hang two rows of hanging baskets on each side.
It's simply a box made of 4"x4"s down the sides and 2"x6"s across the ends (stood on edge and nailed to the 4x4s ~ you can see those in the pic above). I put one end of a 20' long cattle panel inside this "box" and up against one of the 4x4s, nail it using u-shaped fence nails, put the other end of the cattle panel in the other side of the box allowing the panel to bow upwards, and nail the other end to the 4x4. I do this all down the greenhouse, about 5 cattle panels in all (you may have to cut the last one to make it fit without having to overlap it with another). I wire the edges of the panels together.
Next, close in the ends with plywood. This takes some carpentry skills, but it's not hard. Install a door and window in opposite ends. The window is hung upside down and backwards so I can open it from the outside ~ that's handy when you have to vent the house but there are too many plants to get all the way to the end. I hung it upside down so the opening is higher up, thus letting out more heat.
If you don't have the carpentry skills needed to close in the ends or money for the plywood, you can just drap plastic over the ends, leaving one "openable" for a door. The g'house probably won't be strong enough to hang hanging baskets down the sides, but will still work well. If you really wanted to hang things, you might could figure out how to strengthen it maybe with t-posts driven in the ground a foot or so inside the walls and wire the panels to them. Just be sure to cover the t-post tops to keep them from rubbing holes in your plastic. But if you think about it, it'd be easier to just make some stand-alone stands to hang your baskets on ~ maybe something like some tall sawhorses with closet rod between, or check out Craigslist or Freecycle for a clothes rack.
After putting the first layer of plastic on it, I wired lengths of pvc pipe insulation down the sides (the dark lines you see along the walls and roof), then put another layer of plastic over them. This creates an isulating air space like those blowers do, but this one doesn't rely on electricity. Not only does that save a few bucks in electricity, but it sure is nice to not worry about it if the power goes out. Just a month or so ago when it was freezing out, I woke up at 1am to the electricity out, but didn't worry a bit about the greenhouse and just went back to bed. Nice.
I usually cover it with plastic that's long enough to go all the way around it and tuck it under the sides to cover the floor. Like this:
The whole thing's wrapped up like a burrito that way and the plants sitting on the plastic inside hold it on the house. This time the plastic I got was too short, but it's staying on just fine with only a couple feet tucked under and plants sitting on it. I haven't had a strong gust of wind come in yet and will try to avoid that. When I have the plastic all the way across the floor and all the plants on it, even a strong wind gust can't take it off. I scared the hell out of myself one March opening the door during wind gusts of 30mph or so ~ it "inflated" the whole thing, but the plastic didn't slip off an inch.
The ends are made in such a way that the plastic can be pulled between the cattle panels and plywood and held tight. I covered the cattle panel edges with pvc pipe insulation (duct taped it on) to cover the sharp points and cut the plywood to fit inside it snugly. When applying the plastic, I pull it between the plywood and pipe insulation, make sure it's tight, then push the plywood outwards against the pipe insulation. Then I screw on pipe hangers to hold it together.
Lastly, I put some "guy wires" inside for extra strength where I thought it was needed, but now I'm wondering if they were really needed at all. If you build one of these and notice it bowing out in the middle or losing shape at the ends, you may want to add some.
If you live in an area that gets a lot of snow, I'd think this would hold up pretty well, but I don't know for sure since it's rare we get any at all. The snow may be held on by the ridges made by the pvc pipe insulation and build up enough to collapse it. You may could rig up a heater to blow hot air between the two layers of plastic to melt it? Or add more support inside to keep the cattle panels from collapsing. Or maybe you could just cover the whole thing with a slick tarp pulled extra tight so the snow slides off ~ just using that on nights you get snow. I really don't know since, again, I haven't ever had to deal with that.
Overall I LOVE this thing! The shorter one I made years ago was made using the 16' long cattle panels, so was a bit less than 6' tall inside, making it more cozy and easier to heat since I didn't have to heat all that headspace. But once my brugmansias start getting really tall, I'll be glad for the extra room the taller one gives me.
My next experiment will be digging a 4 or 5 foot deep hole for a pit greenhouse, putting in a foot or so of gravel and dragging this over it. Might get some nice geothermal heating that way since the ground here stays over 60 degrees. It sure would be nice to have a greenhouse that stays over 50 all the time. The coolness might even make it so I don't have to vent it as much. That'd be nice!