What you should know about winter citrus fruit in Southern California

One of the greatest blessings of California living is winter’s crop of citrus fruit. Just when vitamin C is most needed, we have a ready supply of it on hand. Now is the time that navel oranges and their varieties — Robertson and Cara Cara prominent among them — begin to ripen and will do so over the next four months. 

Indeed, residents of Southern California reach the conclusion, sooner or later, that the most desirable fruit trees to grow are citrus – oranges, mandarins (tangerines), grapefruits, lemons, limes and kumquats. This is not to say that apricots, plums, nectarines, figs and apples won’t produce. In fact, certain varieties of these trees may yield so much fruit all at once that you end up giving most of it away. 

But this is part of the problem with deciduous fruit trees; the fruit ripens during a period of a few weeks. With evergreen fruit trees – citrus, avocado and guava – harvesting takes place over a period of several months. Where citrus harvest is concerned, there is a bonus to being lazy: the longer the fruit stays on the tree, the sweeter it gets.

If you had one Valencia orange tree (for spring-fall eating) and one navel orange tree (for winter-early spring consumption) in your backyard, you would have fresh oranges to eat practically every day of the year. There are also varieties of lemon (Eureka and Lisbon) and lime (Bearss) that produce year-round. Finally, certain kumquats and their hybrids fruit nonstop and are used for ornamental purposes either individually or in hedges. Kumquats are the hardiest of all citrus.

Once a citrus tree is established, it should not require much maintenance. Many homeowners with 20- or 30-year-old Valencias proudly testify to their complete neglect of these trees. Yet there they stand – botanical marvels of greenest green foliage and orangest orange fruit. They have lived through a multitude of California droughts and earthquakes, implacable as the original Valencias that once grew upon the rugged Spanish plain. The oldest orange tree in California today is a Valencia in Valley Center (north San Diego County), planted in 1869. It still produces a respectable crop, while the oldest navel orange, also still producing, is located in Riverside and was planted in 1873. 

Pruning of citrus is only necessary for removal of dead or diseased wood or to keep the tree in bounds. Lemons require the most pruning, primarily of vertical growing water sprouts that show great vigor but no fruit production. Lemons and limes are more sensitive to cold than other citrus. Now that the coldest part of winter is gone, you will want to apply fertilizer. It will soak into the ground with our seasonal rainfall, which is typically most abundant in February.

Citrus in containers may defoliate during the winter. When this happens, replace the soil in the container, prune, and fertilize lightly. As the weather warms, foliage will return. Containerized plants may require fertilization several times during the year; an occasional liquid feeding with fish emulsion or seaweed, combined with application of slow-release Osmocote granules should keep your potted citrus happy.

A common complaint concerns homegrown grapefruit that lacks sweetness. If you try to grow the red-fleshed grapefruits – such as Ruby – that are produced commercially in Arizona and Texas, you will be disappointed. The grapefruit variety most suited to our area is Oro Blanco, which you can also grow as a hedge.

An excellent choice for a small ornamental tree with year-round interest is the kumquat or one of its relatives. The kumquat is to the orange what the crab apple is to the apple – a small, tart version of the larger fruit. The limequat – a cross between a kumquat and a lime – has the taste of a lime and the cold tolerance of a kumquat. It is laden with soft-skinned yellow fruit during the winter. The calamondin – a cross between a kumquat and a mandarin – is also cold hardy, and when mature, is adorned with hundreds of fruit at all times. Any of these kumquats can be used as a 4- to 6-foot evergreen hedge.

Most of our citrus tree species trace their origin to China from where they migrated to the Middle East and, eventually, to Europe. The oldest European citrus trees — citrons or sweet lemons — on record were planted in Pompeii, as evidenced by seeds found there, buried in the hardened lava that quickly inundated the city after the volcanic eruption from Mount Vesuvius in 79 AD. 

When I first moved to Los Angeles, I thought there must be a neighbor who didn’t like me. Each morning, I would find large orange peels in my backyard. “Someone is eating oranges and throwing the peels over the fence,” I thought. 

After several weeks of peel collecting, I discovered the source of this nefarious littering. Orange peels were indeed falling out of the sky, but not through human agency. Running along telephone wires above my yard were squirrels — whose deterrence has been the subject of a recent column. These squirrels often carried oranges and, stopping to suck out the sweet pulp, let the peels fall where they may.

John Lingle, who gardens in Long Beach, has found a solution to squirrels that run along block walls, from where they leap onto adjacent fruit trees. He utilizes plastic spikes that are advertised for deterrence of birds, raccoons, and cats as well. Lingle affixed the spikes to his block wall with double-sided Gorilla tape. To protect strawberries and blueberries from squirrel predations, he covers the plants in green chicken wire, a material from which he also makes tall circular barriers around his fruit trees.

Janice Liebee, from La Palma, recommends a product called Repels-All, which she found at a home improvement center.  “It’s safe for animals,” she writes. “It causes a mild irritation to their nasal passages and they don’t come back. I use it in my front yard and it works great for raccoons” — so I imagine it would be effective with squirrels, too.

Gary Dailey, in Riverside County, has learned to keep rabbits out of his vegetable garden by growing crops that rabbits won’t eat, including zucchini, watermelon, and potatoes. “Rabbits will eat the leaves of sweet potatoes,” he adds, “but usually the plants grow faster than rabbits can eat them so it’s not a problem.” 

Due to citrus greening disease and the citrus quarantine established throughout large areas of Southern California, there are a limited number of nurseries selling citrus trees at the present time. I learned from Lingle that Armstrong Nursery in Long Beach is one such nursery. If you know of other nurseries that currently sell citrus trees, please advise. If you do purchase a citrus tree and live in a quarantined area, you should not take fruit you grow outside your property, consume it solely at home, and dispose of any fruit you don’t eat in the trash.

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Remembering the smudge pots of long-ago Los Angeles: How do trees stay warm now?

California native of the week: If you are looking for a living fence that, once established, does not need water, is cold hardy to 17 degrees, and has seeds that provide a precious cosmetic, consider jojoba. Jojoba (Simmondsia chinensis) develops into a large shrub or small tree, up to eight feet tall and eight feet wide, or even larger, and lives for a century or two. A California native xerophyte found in the Sonoran Desert, jojoba (hoh-HOH-bah) can thrive in sand and is being used around the world as a crop for marginal land and as a species that can halt desertification.

This unique plant produces fruits that contain one to three seeds from which jojoba oil, which makes up around 50% of the seeds’ weight, is extracted. Jojoba is dioecious, meaning there are male and female plants and that you will need at least one of each to produce a crop. In the manner of dioecious plants generally — from pistachio trees to date palms — jojoba is wind-pollinated. Although jojoba can survive on little to zero irrigation, it is best to soak it once a week during hot weather during its first few years in the ground. This is done to establish a strong root system so that it can reach its maximum growth rate of around 12 inches per year. Evergreen jojoba has attractive, waxy gray-green foliage and demands a full sun exposure and fast-draining soil.

Please send questions or comments to joshua@perfectplants.com. 

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