Climate is key to making best citrus choice
QWhat kind of citrus is the most tolerant of cold weather? We get very hot summers, but the winters can occasionally get below freezing. What can I do to protect my frostsensitive plants from the occasional frost?
ACitrus can be grown in five general regions of California: the southern coast, inland south, desert valleys, the Central Valley, and the northern coastal valleys. The coastal climates are influenced by the Pacific Ocean, and many areas rarely experience significant frost. The inland valley areas are colder, but some pockets are geographically protected from the cold and are suitable for citrus.
Frost tolerance can mean several things. A tree can be completely defoliated (lose all of its leaves) at 32 degrees, but once the weather warms up it comes back to life. This is more likely to happen to young, smaller trees. If you think your citrus tree is dead because of frost, wait until springtime before removing it. It may come back when the weather warms.
Other times, frost will leave the leaves unscathed but any fruit will be ruined.
Frost-damaged citrus fruit will lose its flavor and become dry and mealy. Once again, this is more likely to occur with young, smaller trees.
For smaller trees, frost blankets may be enough protection. Christmas
lights (the larger, incandescent types) can sometimes provide enough heat to protect from frost. We've also had some success with filling 5-gallon buckets with water and placing them around the base of the tree. (Note:
Do not do this if you have small children around, since a tall bucket with even a small amount of water can be a drowning hazard.)
Once a tree has reached a height of 10-15 feet, it becomes more resistant to frost damage since it's not as close to the ground.
Varieties that are least sensitive to frost include kumquat and some tangerines. Oranges and grapefruits are somewhat more frost-tolerant, and Buddha's hand citron and limes are the least tolerant.
Take advantage of microclimates within your property. Locating citrus (or other frost-sensitive plants) near a heat sink such as a south-facing wall, near a concrete patio or walkway, next to a fence, or near a fountain, hot tub or swimming pool, may give you a few extra degrees of protection. We were able to keep our young lemon and lime trees alive by locating a fountain underneath them for their first few years. Once they got big, we could move the fountain elsewhere. Citrus trees drop a lot of litter, so keep this in mind.
Another alternative is container planting. A half whiskey barrel on a heavyduty dolly can be relocated to a garage or other protected space when there's a freeze warning.
Have questions? Email gardening@scng.com.