Citrus Trees in Arizona: When to Pick Your Fruit and How to Protect It From Frost

In the Phoenix area, most backyard citrus is picked from late fall through spring: many mandarins and early navels in November, most navels and grapefruit starting in December, and Valencia oranges around March. Citrus stops sweetening once it is picked, so taste one before you harvest the whole tree, and cover tender trees on clear, calm nights when frost is forecast.

One of the best surprises for people who move here is walking out the back door and picking an orange or a lemon off their own tree. Here is what to know about picking it, watering it and getting it through a cold night.

When Is Citrus Ripe in Phoenix?

Timing depends on the variety. The University of Arizona Cooperative Extension's guide to low desert citrus varieties lays it out:

• Navel oranges: Early types like Fukumoto are ready by the end of October or early November, Marrs is best in November, and the classic Washington navel usually starts around Thanksgiving or the first of December. Lane Late can be picked starting in January.
• Valencia oranges: These are the late ones. The fruit is not mature until about March.
• Mandarins and tangelos: Clementine types and Fairchild ripen in November, Dancy starts in December, and Kinnow is ripe around January. Minneola tangelos are mature starting in January.
• Grapefruit: Marsh, Redblush, Rio Red and Flame can be picked starting in December, but grapefruit keeps improving on the tree. Many people think it tastes best in March, April or May, once the acid comes down. Rio Red can hang on the tree as late as July.
• Lemons: You can pick lemons while they are still green and use them before the rind turns yellow.
• Limes: Mexican (Key) limes ripen in September, and Tahiti (Bearss) limes ripen in June.

Not sure what kind of tree came with your house? Taste a piece every couple of weeks starting in the fall, and you will learn its timing within one season.

How to Tell If Your Fruit Is Ready

The most important thing to know is that citrus does not keep ripening after it leaves the tree. Lemons, for example, can be picked and used while still green. The safest test for any variety is to taste one.

The tree is also the best place to store your fruit. Fruit left on the tree keeps getting sweeter, so pick what you need over several weeks. That is especially true for grapefruit.

A couple of picking tips: mandarins have thin peels that can tear at the stem end if you pull them off. If you plan to keep them for a while, clip the stem with hand pruners instead. And if you juice navel oranges, drink the juice fresh. Navels contain a compound called limonin that turns stored juice bitter.

Watering Citrus the Desert Way

Daily, shallow watering is a common mistake. The UA Extension guide on irrigating citrus recommends wetting the soil from the trunk to just past the drip line (the outer edge of the canopy) and at least two feet deep. Depending on season and soil, that means every 7 to 28 days, not every day, with sandy soil needing water more often than clay.

Let the top 6 inches or so of soil dry out between waterings, and keep soil and mulch from piling up against the trunk. Leaves that turn dull green and curl in from the edges are a sign the tree needs water.

Hard water can leave white buildup on drip emitters; more on that in Hard Water in Phoenix: What It Does to Your Home.

Protecting Citrus From Frost

Phoenix winters are mild, but frost does happen. A UA Extension frost guide lists average first frost dates ranging from late November in Buckeye to mid-December in central Phoenix. The coldest temperatures usually come right around daybreak, and clear, calm nights carry the most risk.

Some citrus handles cold better than others. According to UA Extension, kumquats and mandarins are the most cold hardy, followed by grapefruit and oranges. Lemons and limes are the most tender, and they can see damage once it drops below about 25 degrees. New growth and blossoms are the most sensitive, then fruit, then mature leaves, then the trunk and branches.

When a frost is forecast:

• Cover the tree all the way to the ground. Frost cloth, blankets or burlap work. The cover should reach the ground at least out to the drip line. Do not use plastic.
• Take covers off in the morning once it warms up. Leaving covers on all winter is not recommended.
• Add a little heat. Old-style incandescent holiday lights or a shop light under the canopy can help.
• Keep the soil moist. UA Extension lists moist soil as one of the simple ways to help a tree through a frost.

What to Do If Frost Damages Your Tree

Resist the urge to grab the pruners. UA Extension advises waiting until the tree pushes new growth in spring, because it is hard to tell dead wood from live wood until then, and early pruning can trigger tender growth that gets hit by the next cold snap. Once spring growth shows you where the damage stops, cut back to live wood and paint any newly exposed bark with white latex paint or whitewash to protect it from the sun.

Frozen fruit can look fine outside but turn dry inside within a week or two, so pick it quickly and juice it.

Questions People Ask

When do you pick oranges in Arizona?
Most navel oranges in the Phoenix area are picked from about late November through winter, with early varieties ready by November. Valencia oranges ripen later, around March.

Does citrus ripen after it is picked?
No. Citrus does not ripen or sweeten after it comes off the tree, so taste one before harvesting and leave the rest on the tree until you need it.

What temperature hurts citrus trees in Phoenix?
Lemons and limes can be damaged below about 25 degrees, while oranges, grapefruit and tangerines may handle about 20 degrees without major damage, according to University of Arizona Extension.

Comparing parts of the Valley? See my Moving to Phoenix guide, compare areas on the Arizona cities page and the cost of living in Phoenix, or start on my home buying page.

Terry Day, REALTOR®, DeLex Realty, 10115 E Bell Rd, Scottsdale, AZ 85260.