Even though we are entering the depths of winter, spring will be here before we know it. Now is the time to start making plans for your spring garden. A key part of any garden is a greenhouse. Today we will take a look at the different types of greenhouses and how you can add this important piece of equipment to your garden. http://www.treehugger.com/green-architecture/build-underground-greenhouse-garden-year-round.html http://freeenergynews.com/Directory/Building/Walipini_Benson-Institute.pdf