I was writing my next blog when I started getting getting calls and texts from friends, old students and others asking me about the actual steps of building the poly-tunnels and row covers I described in my last blog. Additionally, I realized that I was putting up my own polytunnels so below you will see the steps involved. I will assume that you have followed my link to Johnny’s and understand how to make the ribs of the polytunnel, so the real question is how to best install the ribs and tunnel covers.
There are two ways to install the ribs. The first is directly in the ground by pounding the ends into the ground 6-9 inches deep. (See below.). If you are installing the tunnels directly in ground and not over a raised bed, this is the only option. If you are installing over a raised bed both methods will work. 
The second way, and my suggested way is to install PVC holders. This is more work but give you a much stronger and easier tunnel to build. As the tubing is ½ inch in diameter you should purchase a few pieces of 1 inch PVC pipe to make both the holders and bracing. Cut one pipe into 9-12 inch pieces. I have found that in order to screw the tube holder you must first pre-drill the holder. If you look at the holder you will see a hole I drilled into the side of the holder so as to make it possible to then screw the holder to the raised bed.
The ribs should have 1 holder no closer than 24 inches and no wider than 36 inches apart. (The suggested distance is 48 inches. I do not recommend that distance in any area that gets a foot or more of snow in a year.) Here we can see the ribs all installed. Note that in addition to the ribs, there is a top support (made of the same 1 inch pvc that was used to build the rib holders.)
The first year I built this I didn't include the top support (nor is it part of the original directions.) I found that the structure was simply too wimpy to hold up in our upstate climate. The top brace is simply held to the ribs by the use of zip ties. (See below.)
For safety, the end rib should be taped so the fabric or greenhouse plastic doesn't get torn. (You can see that if you look at the closest rib in the third picture above and highlighted in the red circle.)
Now that the frame is complete it could be covered with either Agribon AG19 row cover (good down to 20 degrees) or Tufflite IV Greenhouse plastic (good down to 10 degrees.) I use the first through the middle of October and switch to the greenhouse plastic from October through the end of December. That's right, I said the end of December. (If you have never tasted a winter carrot you simply have not tasted carrots. 
If you look inside you will see at the back end of the bed the carrots I planted in late July (and now are eating with home made hot humus ). In the front bed (you can’t see due to the small size) the carrots I planted in September and should be harvesting in late November and December. Here we can see the cover down and how it will look until then.
One of the other items I left out in my last blog was the suggestion that the ribbed row covers could also be used to extend the season on existing plants that have both flowers and flower buds. What I do each year at the end of September is to take plants like peppers that require a long growing season and transplant them into large pots and cover them with row covers.
As a follow-up on my last blog I also missed a link I should have included. While I told you about Mother Earth News, I failed to give the link to all of their season extenders. Let me correct that now. Follow this link to a whole world of good information: http://www.motherearthnews.com/year-round-gardening-zl0z12onzhir.aspx . While not on exactly the same subject, there is a woman who contributes to Mother Earth News frequently who is best known for her edible landscaping. Her name is Nan Chase and her blog can be foundhttp://www.culinate.com/author/Nan+K._Chase/blog . Have fun.
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