I love the idea of a greenhouse, I think they are less conspicous that having plants out in the open. Also they let you control the weather somewhat. I've been reading a book called Hydroponic food production by Howard M Resh. He's a professor at UC Davis, the book made me a believer in greehouse growing. Check out target.com and search for greenhouses, you'll find some reasonably priced portable houses that pop up like a tent and come in opaque or transparent. The drawback to greenhouses is light transfer, depending on the material, and humidity, which can usually be controlled with just a fan.