I had posted a reply earlier that was somehow intercepted , perhaps because I added a link to the vendor. In any even, I use netting that I purchased from The Greenhouse Megastore.
http://www.greenhousemegastore.com/S...artments/1117/ It is available in different degrees of shading. For vegetables they recommend 45%. I add it as needed, and remove it when it is not. Cloudy days, I just leave it off. Fortunately I have a deck behind and overlooking my greenhouse and I can use a telescoping pole to place and remove the netting. Also, I position it to shade only the plants that need shade. You can see the netting in the photo above the tomatoes. It is folded to allow the sun to shine on the plants in the photo. From my perspective, it works great and lasts for years.
Jack
