Selecting the right citrus for the Mojave Desert

Q. My oranges haven’t ripened on my two year old tree. Some are green and others yellowish with very hard skin and last year’s fruit wasn’t very sweet or soft.  Should I cover them tonight? It will be freezing.

A. The fruit of many oranges are damaged at temperatures of 30°F or a few degrees lower.  The type or variety of sweet orange is highly variable to freezing temperatures. If you think winter temperatures will drop low enough for damage, then throw a sheet over the tree to protect it from cold and wind. Go outside at night and look at the sky. Clear skies are more likely to contribute to lower temperatures than cloudy skies. If there is wind combined with freezing temperatures, fruit damage is worse.

Fully ripe citrus in the Philippines

            They may not be ripe yet. Depends on the variety and time of year. Cold weather can get them to turn orange when they ripen. Oranges in warm climates never turn orange but they are ripe and it is acceptable. My guess from their color is they should stay on the tree longer. Oranges are tropical to subtropical and are not intended to be grown where it freezes. If they are sweet they can handle SOME temps down to about 28F or so. We grow ours in US in Yuma, Az, Corpus Christi TX, south Florida and southern California where it seldom freezes. If it does freeze farmers have crop insurance.

             Ripe fruit handles temperatures a couple of degrees lower than unripe fruit during freezing weather because of their higher sugar content. The sweeter the orange, a couple of degrees lower in temperature is needed to damage the fruit.

            Our desert climate creates winter temperatures too low for growing and producing citrus. You might have a couple of warm winters in a row followed by low winter temperatures that wipe out the citrus.

            Citrus growing areas have warmer winters than Las Vegas; places like Yuma, Rio Grande Valley in Texas, mid to South Florida and lower elevations in California are the US premier citrus growing regions.

            Will citrus grow here? Sometimes, depending on where they are planted and your choice in citrus. Will they produce fruit here? Sometimes, depending on when they flower and the temperatures just before and after flowering and food production.  

            Talk to your neighbors and look around your neighborhood. If your neighbors had luck growing oranges, you might have the same luck. Be suspicious of neighborhoods that have no citrus growing in them at all. There might be a weather and climate related reason for that.

            Pay attention to the type or variety of orange you have. Your calling yours an orange. It has a name or variety besides “orange”. These different varieties of oranges flower and are harvested at different times. Some perform better here than others.

            The “University of Arizona” has published a fact sheet that you can retrieve online called, “Low Desert Citrus Varieties”. Use your favorite search engine and type in what I have here in quotations and look at the last two pages. It will tell you the harvest time for these fruit. Avoid those varieties which should be harvested in the middle of December or later in the winter.

           Take a look at the last page of this document from the University of Arizona. They can be ripe any time from October through March depending on the type of orange and growing conditions. If it gets really cold the fruit can freeze.