The Frost Cometh: Protect Your Plants!

photo by Holly Guenther

Unsuspecting lemon enjoys a sunny day, unaware of impending frost!

Here in the Central Valley of California, we normally enjoy mild winters. However, once every few years temperatures dip below freezing. This causes widespread panic among gardeners, who have forgotten (or perhaps did not know) that many plants in our garden are subtropical and need protection. These plants include citrus, avocado, anything with succulent leaves and bougainvillea, to name a few.

Young plants are most susceptible to frost, but luckily easier to protect because of their small size. For protection, build a frame around each tree (use wood, pvc pipe, etc) and throw a cover of burlap, clear plastic or an old bed sheet over it.  Make sure the top and sides are covered.  If you use plastic, you can leave the cover on during the day. Otherwise, remove the cover to allow sunlight to reach the plant.  (note: draping covers over a tree without a frame will not protect it, as foliage touching the cover will be damaged by the cold.)

Normally, trees and fruits aren’t damaged unless temperatures stay low for 30 minutes to several hours.  Ripe oranges, grapefruit, and mandarins are injured at 27° to 28° F.  Ripe lemons are less cold tolerant, and may be damaged at 30° to 31° F. Unfortunately, picking fruit before it ripens won’t save it. It’s best to leave fruit on the tree as long as possible. If fruit is damaged by frost, remove it as soon as possible to save the tree energy.

When planting subtropicals in the landscape, plant near buildings and choose southwest exposures when possible. And remember, not all citrus have the same cold tolerance. Kumquats and Satsuma mandarins are the most cold resistant.  The least resistant are limes and lemons.  Oranges, grapefruit, and mandarin hybrids are intermediate in tolerance. Interestingly enough, avocado trees can grow successfully in our area. Choose Zutano and Bacon varieties as they are the most cold tolerant.

If you think a plant was damaged by frost, do not prune. Wait until spring to see how much damage was actually caused. Also, avoid over-fertilizing subtropical plants, and apply fertilizer during late winter and early spring.  Plants actively growing during a frost can be easily damaged.




  1. There is an avocado variety called ‘Bacon’??? LOL! Where’s the one called ‘Salsa’? Or ‘Chips’?

  2. I am loving your blog. I just processed you in Blotanical. I was just in Hawaii and I went on a tour. They said that the reall good avocados there are Bacon Avacados. Funny you should mention them. I’d never heard of them before. I just bought a Meyer Lemon. I love on Vancouver island in BC Canada. Zone 9a. Our resident expert here, plants them against a south wall, strings old school outdoor christmas lights (the ones that get hot) and puts them on a sensor that will turn the lights on when it hits 0 degrees C and tacks up a double thick layer of reemay cloth in before it freezes. His gorgeous lemons have been in the ground for 20 years here. I am going to copy what he did exactly.

    • Thanks for your message, you’re the first person to find me on Blotanical! I’m still figuring that site out. I adore Meyer lemons. I think they make the BEST lemonade. And lemon pie, yum! Your resident expert sounds like he knows what he’s doing. Seems like a bit of work, but we gardeners do what we gotta do to for tasty produce!

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