Mary Beth: This was my project last weekend for my raised vegetable beds.
I got this idea from the Sunset web site and it worked amazingly well. Ray and I modified the design a bit based on how I made the beds which are on a slope and are very irregularly shaped. When I made them I used rocks for the sides of the beds instead of lumber, but it actually turned out to be a perfect way to protect my crops.
Ray used 2 foot pieces of rebar for the stakes. We hammered the bars into the ground along the long sides of the tomato and squash beds and slipped the PVC pipe on each opposite pair creating a half hoop. Then I covered the hoops with plastic.
The plants seem to be responding well. I think the plastic covers over the squash and tomatoes are keeping them warm at night when our mountain temps get down to the low 50′s. Cool nights will slow them down, but by using hoops to retain the warmth it should extend the season so I can have veggies well into October and maybe even November.
I also put hoops on my cool-weather plant beds, but I covered these with netting to protect those crops from the birds.
This is one of those “Why did I take so long to do this?!” projects.