Nobody seems to be responding to your Q and I suppose that the econonics of using cattle panels has much to do with that. Some have used wood, some PVC and just about any other material that could be supportive but as one horticulture professor put it: You just can't construct a long term structure that beats the galvanized arches for price.

The plans I have seen involve building a low, vertical wall to attach the bent cattle gate to, probably 2-4' high. The size of that wall determines the size of the finished structure.

I have made one and if you are a backyard gardener, they are fairly simple to build and very sturdy. I made this one 9 years ago. Now there is a 30 by 48 tunnel sitting in its place.
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Here it is after I pulled it out and started to disassemble it.
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I used it one season. I was very happy with it. In fact, I thought about building it again to get my seedlings out of my high tunnel aisles.

Simple construction, I dug 4 holes in the corners and put a 4 by 4 post in the ground 2 feet. I would do a minimum of 3 feet if I did it again. Attached a baseboard all the way around the structure. This was a scrap 1 by 6 for me. Then I bent the cattle panel over in the arch shape. Using fencing staples, I attached it to the baseboards and I zip tied the panels together, from the inside. I covered the ends with foam pipe insulation ( a split garden hose would work too) and I attached the plastic with furring strips.

It ended up being 8 by 12 and served me well for one year. The PVC one behind it was 12 by 16 and I used it for 3 years. Now I have 6 high tunnel and these two are distant memories.

Jay

I agree with bmoser, on a cost per year basis you're not going to beat the standard galvanized steel arches. Sure other materials are cheaper but how long are they going to last and do they increase cost elsewhere. Cattle panels aren't even cheap and you've got issues with ripping the poly and many other things I could mention.

My greenhouse was fairly expensive but properly maintained it could last 50-100 years.

Thank you all, I have changed my mind and will build a hoop house like jrslick above.

Hi,
If you want a really good cattle panel greenhouse, that cost about $150.00 total, lasts a long time, check out texasprepper2 on Youtube. He has a fantastic greenhouse video you may want to see.

https://www.youtube.com/watch?v=-DKlXs8iov0

The pros are, It lasts a very long time, is much stronger against strong winds, and although it's not super wide, it can be as long as you want. other than it being only 7-8 feet wide, I'm sure it can be built wider, it's just that those that I know, that have made it, have only made it in the size in the video. All of them love the greenhouse. The man that made the video uses the greenhouse every year to grow lots of plants too, and has videos of more that he has done to it in some of his other videos.
I just purchased all the parts to make this greenhouse, and can't wait.
Oh, and I also just purchased the cooker that he uses to heat his greenhouse too. It's the Bayou Classic. Of course, I was going to buy that anyway so that I can do my canning outside, when the veggies come in, and not have to heat up the kitchen all summer.

He also has a great book with all the instructions and there is a kindle edition too.
No I am not trying to sell you on all this, I'm just very excited about a greenhouse that a lot of youtube friends have made, that I can't wait to get up myself.
His book also has other things to make with the panels like chicken shacks too. Lots of fun, You will enjoy the video.
Good luck everybody, hope everyone gets the greenhouse of their dreams.
God Bless,
Sheila