Cold Frames, and smaller Greenhouses, are quick and easy to set up and easy to store when they are no longer in use.
They can be used to start seeds earlier in the season, or lengthen the life of your crops so that you can harvest your vegetables later into the season.
Using a smaller greenhouse or cold frame will also allow you to decide if Greenhouse Gardening is right for you. If you enjoy it, you may want to move onto a Larger Greenhouse to grow even more fruits and Vegetables.
Ventilation and Shading:
This design has some thought put into it for the ventilation. As mentioned, Cold Frames or mini Greenhouses warm up quickly, so on hot days the covering will need to be propped open, or removed completely to allow for proper ventilation.
Shade covers can also be added. Shade cloth is used to drape greenhouses so that it does not receive too much sun, raising the temperatures to more than the plants can handle.
Solar Greenhouse Gardening :
This is a great place to start if you want to learn the basics of Greenhouse Gardening. Or, it also has a great video about Solar Greenhouse Gardening. Solar greenhouse