C is for Citrus

Left to right: Meyers lemon, Bearss lime, Valencia orange.

Left to right: Meyers lemon, Bearss lime, Valencia orange.

We have had nine citrus trees in our yard: Meyers lemon, Bearss lime, Kaffir lime, Valencia orange, tangerine, calamondin, Nagami kumquat, and two Navel orange. What a lucky break. Just as the weather turns cold, the herbs freeze and turn brown, the squash (finally) give up, and the long shadows threaten to never allow sun in the yard again, we are rewarded with citrus. The evergreen trees keep their waxy green leaves, and the fruit turns from green to orange or yellow. Out of the dirty neglected yard comes sweet treasures. The fruit on the trees resemble Christmas ornaments. We can’t eat all of the fruit; the trees are so abundant. We sometimes forget to even go pick oranges because the cold weather tells us no fruit should be available at a cold time like this.

We take it for granted.

We shouldn’t.

Citrus trees are absurdly popular, planted in nearly every yard where we live. Yet we continue to ignore them. I wrote about Asian Citrus Psyllid in an earlier post. Citrus trees have other enemies, too. In the mid-1800s, cottony-cushion scale threatened to destroy California citrus. A natural predator was introduced from Australia and saved the day. You might have heard of the Vedalia beetle, more commonly known as the lady bug, and more accurately the lady bird beetle?

California and citrus have a rich and entangled history together. In particular, the navel orange has its roots in Riverside, California.

The evergreen trees lose leaves throughout the year, a few at a time. The first few years that citrus are in the ground, the tree’s concentration is on the root system. The thick leaves engage in photosynthesis as do other fruit trees, but citrus also store the plant’s food there for winter. The maximum amount of food storage in the leaves is in February and March. Hence, pay attention to not prune your tree at this time of year right before the  spring bloom. (Prune may be too harsh word to use in conjunction with citrus. I cut my citrus a little at a time when it starts to grow into a space where I don’t want it. I also cut water spouts–the light green thorny shoots the tree sends upward. Heavy pruning leaves the tree susceptible to sunburn. Thinning to allow light into the tree is a good thing every now and then. Taking out deadwood keeps the tree more productive, and limiting the size of the tree means fewer critters stealing your harvest.) Citrus never has a dormant period as so many deciduous fruit trees do.

Part of the allure of planting citrus is the abundant landscaping options that citrus offers. For example, citrus comes in many sizes: typical tree size, semidwarf, and dwarf size. No matter what type you plant, the actual size of the fruit remains the same. Citrus does great planted directly in the ground, but does just as well in containers or espaliered along a fence or wall. Citrus can also be used as a privacy shrub. Because the tree doesn’t shed all of its leaves at once, it truly is an “evergreen.”

Citrus can suffer from damaging freezes which happens about every decade in California. If the tree is young and a hard frost is forecast, you can put a sheet over the young tree or shine a flood light on the tree on the coldest nights. Old-school Christmas lights can do the trick, and look nice. The halogen lights won’t provide any frost protection, however. Don’t prune frost damage right away, as that damage will protect the tree from further damage if another frost happens. Do cut off the affected fruit.

Tonight is our first expected freeze (December 3). We should probably put a sheet over our lime tree, as it is relatively young. Limes thrive in warmer areas, we just happen to be lucky–after a few years of establishing itself in the ground, our lime tree is picking up pace in lime production. We should harvest most of these limes today so they are not lost in the frost. We will probably have lime honey chicken for dinner, with lime slices in our water. We can juice the limes, too. The lime juice (lemon and Valencia oranges work, as well) in ice cube trays and use them for the next several months in cooking or in glasses of ice water. The juice of Navel oranges (which taste the best) develops “off” flavors a day or two after juicing.

Limes are actually ripe when they turn yellow, not green.

Limes are actually ripe when they turn yellow, not green.

A little-known fact about citrus: yard waste is the perfect mulch. Yard waste (wood chips grass clippings, fallen leaves) actually protect citrus by enhancing the growth of two biological control agents: Trichoderma harzianum (a beneficial fungus) and Pseudomonas fluorescent (a beneficial bacterium) which protect the trees from Phytophthora root rot that are present in much of the native soil.

About master kindergardener

Santa Clara County Master Gardener since 2007, Mom since 2009, Gardener since birth.
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