Botanical Gardens
Favorite Gardens
Water Conservation Garden
thegarden.orgThe Water Conservation Garden, as might be guessed from the name, focuses primarily on plants for low water gardens.
San Diego Botanic Garden
sdbg.orgA very large garden with several different areas including a fun children's garden, a California native area, a bamboo garden, and many more.
San Diego Zoo
animals.sandiegozoo.org/plantsWhile most might not think of the zoo as a botanical garden, the plant collection is very impressive. They offer occasional botanical tours and a lot of information on their website.