Can I Protect That Almost Ripe Orange This Winter?

Advice for the Home Gardener from the Contra Costa Master Gardener Help Desk

Client's Question:

In a telephone conversation with the client, he asked if he havested his navel oranges early, would they ripen off the tree? And if he doesn't harvest them early, what can he do to protect the tree and fruit?

Response from the CCMG Help Desk:
Thank you for your call this morning about your navel orange tree. Fruit should be harvested when it has developed full color and, most importantly, full flavor. Citrus turn color in fall when they are exposed to cold temperatures, but this does not affect the fruit sweetness. Navel oranges may not be ready to harvest until the late winter, and Valencia oranges are usually mature in the summer.

The best place to store the fruit is on the tree. Once you pick the fruit, it does not increase in sweetness or ripen more fully. Unfortunately, freezing temperatures don't care if your oranges are ripe or not! However, if you do pick the fruit, it will keep for about 4 to 6 weeks under refrigeration. (Note:  Commercial orange growers basically use the orchard's trees as their warehouse making multiple pickings as they ripen. If a freeze is predicted, growers will usually pick all the oranges and sell them for juice).

blanket+tomato cage
for young citrus
photo: FarmerFred.com

Frost Protection
large mature lemon tree
photo: RedwoodBarnNursery.com

As I also mentioned concerning protecting your orange tree from cold temperatures, you should make sure the tree is well watered ahead of the cold. Moist soil holds heat better than dry soil. If you can, build a scaffold over the tree and cover with a heavy sheet during the night (or daytime freezing) all the way to the ground. Don't use plastic and try to keep the cover off the leaves as cold temperatures may harm the tree wherever the cover touches. You could also string outdoor lights (not LED) to add warmth.

For even further information on protecting citrus in the winter, I would recommend two publications "Frost Protection for Citrus and Other Sub-Tropicals" (http://anrcatalog.ucdavis.edu/pdf/8100.pdf) and “Citrus for the Home Garden in Contra Costa County”.(//ucanr.edu/blogs/slomggarden/blogfiles/4260.pdf).

Please contact us again if you have more questions.

Contra Costa Master Gardeners Help Desk

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 Note: The Contra Costa Master Gardener Help Desk is available year-round to answer your gardening questions.  Except for a few holidays, we're open every week, Monday through Thursday for walk-ins from 9:00 am to Noon at 75 Santa Barbara Road, 2d Floor, Pleasant Hill, CA  94523. We can also be reached via telephone:  (925) 646-6586, email: ccmg@ucanr.edu, or on the web at http://ccmg.ucanr.edu/Ask_Us/