We can grow things year-round. But, you can't just grow ANYTHING at any time.
1. Where exactly in San Diego will determine more information. If you are directly on the coast (within one mile of the ocean with no terrain obstructions), you will have drastically different conditions than someone who lives 10-15 miles away from the coastline with hills between the ocean and them.
2. I highly recommend Anderson Nursery for learning some specifics about our area. They hold free classes on Saturdays and there are two locations. If you live closer to the coast, then I recommend visiting the Point Loma location. If you live further from the coast, then the Poway location will have more experienced employees for your micro-zone.