The closest thing to snow during a Bay Area winter is the occasional visit from Jack Frost. This morning we awoke to find the garden covered with a frost dusting so I went out early to examine the fuzzy ice crystals that formed overnight before the sunshine chased them away. The Broccoli florets need cool weather to grow those sweet tasting heads that garnish our winter salads. Fortunately they can endure a freeze and still taste fine when they’re defrosted. We just don’t let them freeze and thaw repeatedly.
This Butterfly bush ( Buddleia davidii) will produce fragrant pink-purple flowers later in the spring, once it recovers from the frost. After winter has passed we will trim the plant back to foster new growth and more blossoms.
Meanwhile our Strawberry plants stay huddled close to the ground so their leaves will be protected from the effects of a hard frost. Later this season we'll remove the damaged leaves allowing the plant to continue growing, creeping along the flower beds and producing more delicious berries next year.
Plants most vulnerable to frost damage are the citrus (orange, lemons and limes) and most tropical plants. Rain helps - as well as watering - because plants are better protected when they're hydrated and full of moisture. A dry plant suffers more severe damage because the cell structure is vulnerable to the ice crystal expansion from within. Frozen water outside the plant walls actually insulates and protects the plant! Would you believe that?
Other frost damage protection includes covering the plant with an insulated cloth to give a blanket of protection from overnight lows, but often the branches in contact with the cloth will still freeze. And finally, applying a fogging spray to add a shielded coating to the plant surface is suggested, but I still believe misting with water works best and provides the cheapest solution.