The hardest part about making a greenhouse shed from greenhouse shed plans is building a roof that lets light in and is still waterproof. There are many materials to make sky lights for roofs but most of them are very expensive. I found this great greenhouse shed roof material that is a clear PVC roofing panel. It is made by Palruf and is sold at Home Depot. The literature says it is 90% clear and is about $14.00 for 26″ x 8′ long panels. They also have all the other parts to install the product. Since the product comes in 26 inch widths it is easiest to screw it to the roof rafters which are 24″ on center. The 2″ extra is used for the overlap between the panels.
So even if you don’t have a good set of shed plans you can still simply install a roof that lets plenty of light in to grow your plants!