The problems I've had with a greenhouse are the wild swings in temperature. There were times this year when morning temperatures, around the time I was leaving for work, were below freezing with ice on tops of any buckets, etc. By mid-afternoon, the temperatures had increased to mid-eighties making the greenhouse smoking. It takes money, equipment, time, and effort to keep those temperatures moderate and even - something already managed in my house. After killing off a round of seedlings, I decided to just keep them in the house until they could be hardened off and left outside.