The zone you live in may affect what you can plant in your garden. Each area has a zone. For example zones 22-24 is mostly Orange County (this info can be found on page 51 of the Sunset Western Garden Book). Now each plant is given varioius zones that they will grow in so before picking the plant you like make sure that it grows in your zone.
Zone 22 - Colder-winter Parts of S. California's Coastal Region
Growing season: Mar. to early Dec. Winter lows seldom fall below 28 degrees F/-2 degrees C (records are around 21 degrees F/-6 degrees C), though colder air sinks to this zone from Zone 23. Summers are warm; rain comes in winter. Climate here is largely oceanic.
Zone 23 - Thermal Belts of S. California's Coastal Region
Growing season: almost year-round (all but first half of Jan.). Rain comes in winter. Reliable ocean influence keeps summers mild (except when hot Santa Ana winds come from inland), frosts negligible; 23 degrees F/-5 degrees C is the record low.
ZONE 24 - Marine-dominated S. California Coast
Growing season: all year, but periodic freezes have dramatic effects (record lows are 33 degrees to 20 degrees F/1 degree to -7 degrees C). Climate here is oceanic (but warmer than oceanic Zone 17), with cool summers, mild winters. Subtropical plants thrive.