As name suggests, this is syracuse, ny. Considering purchasing a greenhouse (Sunglo) to attach to side of garage. Had not seen the idea of insulating the ground discussed to any real degree. Some ideas I've seen are to put a vertical styrofoam board two feet down around the perimeter. Was also wondering of excavating existing soil (I was going to put gravel down anyway with a brick walkway down the middle) and laying styrofoam insualtion boards flat, then cover with several inches of gravel. All of this to insulate the house from cold soil conditions coming in from surrounding area in winter. Was thinking I could deal with any drainage concerns by not being precise with how the styrofoam fits, as well as poking holes in it through the gravel if need be. Does anyone have a thought on this - wondering if any part of this idea makes sense. Thanks.