Citrus are among the most iconic trees of California. A symbol of the sun and the warm winters that drew many people to California. Here in Northern California, we are not quite in the classic citrus growing area, but citrus do pretty well here provided you are comfortable with the slight risk that they will be wiped out by a historic freeze.
Citrus belong to the family Rutaceae, which contains few other plants familiar to most Californians. Unfortunately, the taxonomy of Citrus has become extremely complicated in recent years. Geneticists have discovered that most of the familiar citrus varieties are actually hybrids of several wild species, primarily C. maxima, medica, reticulata, micrantha. For this reason, it is much easier to refer to citrus by their common names which are stable and (mostly) clear to everyone.
In general citrus are fairly drought and heat resistant, and tolerate mild frost but not severe cold. Most will require protection during exceptionally cold winters (when temperatures drop to or below the mid 20's) but tolerate the average winter frosts without complaint. However, not all varieties are equally hardy--kumquats reportedly tolerate to 15-18 degrees and can probably be considered fully hardy in our area, while limes are slightly more frost sensitive than other citrus and are rarely grown successfully here.
Citrus are one of the few trees that can develop a nitrogen deficiency if not fertilized regularly. They do suffer from some pest problems, but nothing too serious is present in our area currently. Unfortunately, citrus greening disease (also known as huanglongbing or HLB) is present in Southern California, and has killed many trees there and in Florida. It is probably inevitable that it will arrive here at some point, but hopefully resistant varieties will be available by then.
Overall, citrus are a good choice for a small, drought tolerant evergreen, and are one of the easiest fruit trees to grow in our area. They can also be used as screens due to their dense foliage. Just be aware that most trees will likely die in the coming decades as HLB spreads north.
Citrus belong to the family Rutaceae, which contains few other plants familiar to most Californians. Unfortunately, the taxonomy of Citrus has become extremely complicated in recent years. Geneticists have discovered that most of the familiar citrus varieties are actually hybrids of several wild species, primarily C. maxima, medica, reticulata, micrantha. For this reason, it is much easier to refer to citrus by their common names which are stable and (mostly) clear to everyone.
In general citrus are fairly drought and heat resistant, and tolerate mild frost but not severe cold. Most will require protection during exceptionally cold winters (when temperatures drop to or below the mid 20's) but tolerate the average winter frosts without complaint. However, not all varieties are equally hardy--kumquats reportedly tolerate to 15-18 degrees and can probably be considered fully hardy in our area, while limes are slightly more frost sensitive than other citrus and are rarely grown successfully here.
Citrus are one of the few trees that can develop a nitrogen deficiency if not fertilized regularly. They do suffer from some pest problems, but nothing too serious is present in our area currently. Unfortunately, citrus greening disease (also known as huanglongbing or HLB) is present in Southern California, and has killed many trees there and in Florida. It is probably inevitable that it will arrive here at some point, but hopefully resistant varieties will be available by then.
Overall, citrus are a good choice for a small, drought tolerant evergreen, and are one of the easiest fruit trees to grow in our area. They can also be used as screens due to their dense foliage. Just be aware that most trees will likely die in the coming decades as HLB spreads north.