We are spoiled here in the Bay Area with a great climate that allows us to plant a wide range of plantings. These range from sub-tropicals, to more temperate plants and even bulbs. Occasionally however, temperatures will drop down below freezing, killing borderline plants. Frequent casualties are Bougainvillea, Lantana, Heathers and soft stem perennials. When it gets down into the low 20’s other plants such as Eucalyptus can also be in danger. This is just a part of dealing with climate changes from season to season. On plantings that grow quickly the best solution is just to replant after a freeze. For other specialized plants or plants that aren’t must haves, better to replant with something more hardy. Sunset garden book is the best resources for finding your plant zone in California. Keep in mind that micro-climates such as cold sinks and other phenomenon can make certain areas colder or warmer.