Time to Maturity
When one reads seed packs, the information includes the time to maturity. This means how long it will take the plant to grow from planting to its ripe fruit. For example, the days between planting a corn seed to when the plant produces a juicy ear of edible corn.
There are early and late season varieties, and for San Francisco I recommend the early season (or short season) plants. We do not have warm enough weather conditions to support slow growing summer vegetables. And, if you don't have full sun, that adds days to maturity as well. Soil quality, of course, goes into maturity calculations as well.
Here are two crops, celery and dwarf kale, that we planted in the summer of 2012. They are just now reaching maturity. Yes, they over wintered and that means cool climates, and we also planted them in nearly full shade. They grew fine, but it took eight months instead of the advertised five. It's good to experiment, however, to know what plants will tolerate shade so you can take advantage of all the space in your garden.