The best way to design a California garden is to realize that California is one of the unique areas of the world that gets no rain for during it warm season. So any plant that you water during the warm season is consistent with our rivers, lakes and streams only. California plant communities will recognize a lawn or English garden as a riparian area. Our other site, www.mynativeplants.com, tries to do this for you.
You can look up the plant community that we think existed for your city here.
You can look up the plant community that we think existed for your zipcode here.
You can read about California plant communities and the plants within them.
California native plant Communities and Companion Plantings. How to design your California Landscaping with a mind to California mycorrhiza and a native plant communities.
Habitats (This is partially outdated, sorry)
You can also see what community the plant you are interested in by going to the individual plant page and look at Communities.
Plants from adjacent plant communities can usually be planted with just a little thought. Coastal sage scrub types can usually grow chaparral and oak woodland plants with minimal problems.
If you plant plants that were native on your site you are planting for birds, butterflies and native bees. A well planned native garden that incorporates plants from the surrounding community uses almost no water, no fertilizer and doesn't attract the rodents. (Don't laugh, native gardens do not usually have Norway rats or field mice.)