FIMBY: As the citrus season begins, advice for backyard growers

We’re on the cusp of citrus season, which in the Sacramento area stretches from November well into spring.

But the trees/bushes/shrubs, which are beautifully green during these months when so many other trees are bare, come with some challenges. Raising a crop of oranges, lemons or mandarins is not like growing apples or peaches.

So we’re tackling a few issues that come up with citrus trees in the next several weeks:

Citrus splitting is not from disease or pests, folks with UC Agriculture and Natural Resources note. Often it involves a combination of weather and situational issues, such as stressed trees and hot, dry winds. Fluctuations in soil moisture and fertilizer also can bring it on. Oranges are the most susceptible, but mandarins and tangelos can split, too. So can that autumn non-citrus favorite, pomegranates.

If an orange tree wasn’t being irrigated regularly during late summer and early fall, the tree reacted thirstily when the rain finally arrived.

The moisture gets sucked up from the roots into the ripening fruit, swelling the juice cells. The rind is not able to expand fast enough to hold the extra moisture, and it cracks open. Any fruit that was sunburned during summer will be more susceptible to splitting.

If your fruit is splitting from navel to stem, remove it from the tree and discard it in the green waste bin. It won’t ripen properly, and the exposed flesh will attract pests. Keep your fingers crossed that the rest of the oranges will be able to grow to full sweetness.

Then next year, establish a regular irrigation and fertilization schedule for your citrus, and stick to it through fall, or until rain is a regular occurence.

Also, pay attention to the National Weather Service forecasts, especially in summer and early fall, and water your tree a few days before hot, windy weather is expected. After the hot spell ends, irrigate lightly, then resume the regular watering schedule. Spread out fertilizing the tree through the year. Give it small monthly feedings rather than a single large application. A slow-release organic fertilizer is preferred.

Spread a good layer of mulch — at least 2 inches of compost, leaves, straw or wood chips — over the soil under the tree out to the drip line. But to prevent diseases, avoid mulching within about 6 inches of the trunk.

Oranges tend to go through cycles. A heavy crop year can exhaust it, so it produces fewer flowers and fewer fruit the next year. How to mitigate that somewhat: Don’t leave the fruit on the tree too long into spring, and make sure the tree is fertilized and well-irrigated after the big crop is harvested. Save any pruning until summer.

Ideally, citrus fruit is thinned when it is still small and green — say, 1 to 2 inches across. This allows the tree to put the energy into the remaining fruit.

Sometimes an overloaded tree will thin itself, in a natural phenomenon know as “June drop.” This is perfectly normal. But the tree owner still should check the branches in late spring or early summer, thinning fruit by hand. (Cut, don’t yank it off the branch.)

But if you, like me, believed there were so few oranges on the tree this year that it wasn’t worth examining, you may have some surprises: Now, as the fruit starts to turn color, the few but thick clumps are obvious. I found one branch with fruit so dense it resembled a grape cluster. Time to get out the sharp pruners and take some weight off the tree. Again, cutting, not yanking.

For the remaining fruit, I propped a strong tomato cage under the branch. A length of 2-by-4 wood also works. I’ve seen trees with so many 2-by-4s holding up branches that they look like a small fence. Be sure to check that any supports stay upright during a windy day.

Limes are easiest to determine ripeness: They can be harvested green, but with a little give in the fruit. Fully ripe limes actually are yellow, when they lose some of their bite but retain their lovely flavor.

Lemons of course turn yellow. Be patient and let them come to full color before picking, especially golden-yellow Meyer lemons.

Important: Oranges, mandarins and tangerines aren’t necessarily ripe when they turn completely orange. Pick them too early and they’re likely to be sour.

Best test: Pick one fruit each week. The fruit should give a little when squeezed; avoid ones that are still rock hard. Taste it! Keep doing this until you get a sweet one. Then harvest only what you want right then. Citrus can be “stored” on the tree for several weeks.

No.  The oranges will be at different stages of ripeness and many will be wasted. Citrus does not ripen further after it is picked. Be aware of the ripening schedule. Satsuma mandarins grown here will be ready soon — hence Placer County’s Mountain Mandarin Festival in November — while navel oranges tend to be ripe starting in January, when the fruit has acquired a kiss of sweetness from the cold weather. Depending on the variety, tangelos, tangerines and kumquats ripen in winter to early spring.  Valencia oranges’ harvest season is summer.

Yes, carefully. Grapefruit can be very susceptible to freezing weather, but we have fewer hard freezes during winter these days.  A small tree with small fruit, such as the Cocktail grapefruit, can do well here. Keep an eye on the frost forecasts, and be prepared to cover it if temps threaten to go below 28 degrees F.

As a rule of thumb, lemons and limes need protection below 32 degrees, while oranges should be protected below 28 degrees.

The citrus variety most cold hardy is the yuzu bush, which can tolerate temperatures down to 20 degrees before it needs protection. That’s according to Four Winds Growers, which supplies many of the citrus trees sold in local nurseries.

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For an excellent overview of citrus growing and care, see “Citrus Growing in Sacramento” on the linked page, from the Sacramento County master gardeners.