Olive trees are native to the Mediterranean, grown in rocky soil without irrigation. Rocky soil without irrigation? Sounds like a perfect fit for Amador County! They are good drought tolerant landscape trees for our area and over the last few years many homeowners planted mini olive groves.
Planting olive trees comes with a major responsibility, even if used as part of a landscape. They can be messy and if you allow the fruit to rot on the ground you can get an infestation of olive fruit fly. Your fruit flies can travel to commercial olive groves, impacting their crop. To control the fruit fly, use traps and pick up fallen fruit. Learn more about controlling the olive fruit fly at http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn74112.html.
If you want to harvest olives for home use, they fruit best with deep monthly irrigation. Be sure to plant them in well-draining soil; they do not like to sit in wet soil in the winter. Olive trees need long summers, heat and full sun. Pay attention to winter temperatures; below 10 degrees will kill them, below 17 degrees will damage them and below 28 degrees will damage the fruit. Sunset Western Garden Book puts them in zone 9, but they grow locally in Sunset zone 7 with the preventative care used to grow citrus. Cold-hardy varieties include Ascalano, Mission, Arbequina and Picual.
Fall is the season to harvest olives, but olives aren’t a fruit you pop into your mouth right away. When I was a child my family lived in Michigan for a few years. We visited relatives in Winters one fall and my father picked fresh olives to play a joke on friends back home. He offered California olives, fresh from the tree – what a treat! His friends weren’t sure how to react when they tried to eat one; fresh olives are incredibly bitter. They didn’t know if they should be polite and eat this gift or spit it out. My dad would laugh and explain that olives must be cured to make them edible. Curing methods to leach out the bitter oleuropein compound include using dry salt, brine, water or lye.
If you want to harvest and cure olives for eating, different varieties are preferred for different curing methods. Manzanillo works well for a lye-cure; Mission is preferred for a dry salt cure; Kalamata is ideal for Kalamata-style water-cured olives; and Sevillano is best for Sicilian-style lye-fermented olives. UC ANR has a great free publication (#8267) on processing olives at http://anrcatalog.ucanr.edu.
To learn more about how to grow, harvest, cure and preserve olives, join UCCE Master Gardener and Master Food Preserver volunteers from 9-12 Noon on Saturday, October 17 at the GSA Building at 12200B Airport Road in Jackson. The class is free and no reservations are required. UCCE Master Gardener Debbie Hillel will explain how to successfully grow olive trees and UCCE Master Food Preserver Sue Mosbacher will demonstrate multiple curing and preservation methods.
UCCE Master Gardeners of Amador County are available to answer home gardening questions Tuesday through Thursday, 10 am to noon, by calling (209) 223-6838. Walk-ins are welcome at our office, located at the GSA Building, 12200B Airport Road in Jackson. You can also email your questions to firstname.lastname@example.org. UCCE Master Food Preserver volunteers are available to answer home food preservation questions by calling (209) 223-6857 or by emailing email@example.com. Visit both groups online at http://cecentralsierra.ucanr.edu. Both groups are also active on Facebook.