Olives are the earliest crop known to be cultivated by humans, having been grown and harvested for at least six thousand years. Originating from the Turkey/Syria border area, olives are a quintessential Mediterranean tree, and thrive in Benicia’s warm summers and mild winters. Several artisanal olive oil companies have sprung up in the area. In local gardens, their familiar gray-green foliage lends an immediate air of classical antiquity. But pressing and curing olives at home has become something of a lost art in this country. For the adventurous foodie with access to productive trees, it can be a richly rewarding pastime.

You may already have a fruiting olive tree or two in your yard, and wondered about how to bring it into production. John Mikolajcik, owner of Mid City Nursery in American Canyon, says, “Olive trees are not that picky—they’re easy to grow.” If you don’t know what variety your tree is, some trial and error with harvesting and curing might be in order. According to Rey Robledo of The Olive Tree Farm in Sonoma, Tuscan varieties (Cerignola, Frantoio, Leccino, and others), the Spanish Manzanillo and the French Picholine are ideal for Benicia’s soil and climate. These bear excellent fruit for both curing and pressing. Sold only in containers, olive trees can be purchased in a wide range of sizes and prices and planted year-round.

Unlike many other fruits, the different colors that olives come in are due to the ripeness of the fruit, not the variety. Most olives are ready to harvest when the juice turns cloudy, at the “green ripe” stage in late September. They ripen to an uneven reddish-brown through November, finally darkening to the “naturally black ripe” stage by early December. Olives in this stage have a high oil content and are easily bruised. If harvested for eating they need to be handled with care; handpicking is essential as damaged fruit will usually not survive the curing process.

For edibility, olives are processed, or “cured,” to remove the oleuropein, which is found in the leaves and fruit of the tree. Oleuropein is non-toxic but extremely bitter. Curing neutralizes this compound in different ways, each resulting in particular tastes and textures. The easiest and quickest way to cure olives at home is with water. In this method, the freshly picked olives are sliced or cracked to expose the interior of the fruit, and then immersed in water, which is changed once a day for five to eight days and then soaked in finishing brine with salt and vinegar. Kalamata olives are the most commonly known of water-cured olives, which retain some of the oleuropein and its bitterness.

Brine curing is also an easy method where the olives are soaked in a solution of water and pickling salt over a number of months. A fermentation process takes place during brining, which alters the flavor profile in characteristic ways. Dry salting is another simple option, resulting in a shriveled olive that is slightly bitter and quite salty. Lye curing is perhaps the last frontier for home olive processing, but it needn’t be intimidating. Following some basic precautions, lye will quickly and completely neutralize the oleuropein in the olives, leaving a buttery flavor that is most recognizable in the canned olives we grew up with.

After curing, olives can be preserved in different ways. The UC Davis Division of Agriculture and Natural Resources publication, “Olives: Safe Methods for Home Pickling (Publication 8267),” was written specifically for the home olive canner and includes recipes, curing methods, precautions for handling lye, and preserving methods.

In addition to curing for eating or cooking, olives can be processed at home for their precious oil. Historically relying on large stone grinding wheels drawn by livestock, DIY olive oil production is currently something of a wild-west scenario. Expensive grinders and oil presses may be purchased, but with a streak of “maker” inventiveness and experiments of others posted on YouTube as a guide, the necessary equipment can be rummaged or cobbled together for much less depending on the scale of the operation.

Whether the final product is olives eaten out of hand or from golden bottles of silky oil, harvesting and processing olives at home is a nutritional, gratifying reconnection with a deep agricultural and culinary history. 

Additional Resources:
UC Davis Publication 8267
Il Fiorello Olive Oil Company
Sepay Groves Olive Oil
Olive Tree Farm Nursery