Here in coastal NorCA, we get maybe 3-6 days of frost in a year. Microclimate-wise, there's only 2 spots on our lot that ever suffer really cold air, as houses, walls and hardscape protect all the rest.
We're halfway through spring here and the weeds are having a great old time, LOL. In CA weeding is pretty much a "11 months out of 12" activity. There's a big downside to all that mild weather and greenery!
So no need for a greenhouse. But everybody loves "garden rooms". I can't think of anyone who doesn't - man or woman.
Below is my dream 'garden room'. Being built on the Filoli Estate in Woodside, CA by the Bourne family (wealthy from silver mining in the Sierra Nevada mtns) and later owned by Lilian Matson Roth of the Matson Steamship line. She owned several estates, and this was her "gardening" estate. You might be familiar with the exterior of the house - it was used in the old "Dynasty" TV series, as well as in many movies.
When Mrs. Roth died, the estate is now owned by the National Trust for Historic Preservation. Admission is by reservation, which allows you to tour the house and 17-acre gardens. It's about 40 miles south of San Francisco and absolutely beautiful in the early spring (March to mid-May). Summer is not as favorable, IMHO - altho roses will be blooming, nearby city of San Jose has a much larger municipal Rose Garden for rose enthusiasts.
The single-story, single-room Garden House has two sets of French doors - you can walk straight through it, with either side having a pair of chairs and potted plants galore. The marble table is set in the middle, and the floor is two colors of Italian marble. Always cool and deliciously shady, even in the heat of summer.
