Roger's tree pick for April: olive

The olive tree is a plant native to the Mediterranean region, tropical and central Asia and various parts of North Africa.

Its classification is in the Oleaceae family and the main genus is Olea europea (pronounced “OH-lee-uh yoo-ROE-pee-uh”).

The olive has a history almost as long as that of Western civilization and has been a profitable tree crop in the warm growing regions of the world for centuries.

It is believed to have originated in Syria or southern Turkey and has been grown in the dry Mediterranean region since 3000 BC. The spread of the olive tree migrated to Greece, Rome and beyond for its fruits and the olive oils at that time.

The olive requires a long, hot growing season to properly ripen the fruit, no late spring frosts to kill the blossoms and sufficient winter chill to ensure fruit set.

Trees will reach a height of 25 to 30 feet or more at maturity and can be as broad in the overall canopy as well.

The olive tree is evergreen and maintains wonderful blue-gray willow-like foliage that blends well into a California-style drought-tolerant garden.

As the trees mature they begin to take on a gnarled, picturesque trunk and branching structure that can become quite handsome and almost like a living sculpture.

I have used the olive tree in my landscape craft for years and am always in awe of some of the real old trees that can be found around Fallbrook and in Southern California that can be well over 100 years old and still surviving with no additional irrigation other than the natural rain season.

Due to their tenacious hardiness, olive trees can be easily transplanted and the olive has in more recent times become a popular landscape tree that gives a dramatic mature look to any garden, be it an old or a new landscape setting.

I have imported some ancient 100-year-old olive trees from the central California valley for some of my projects and they have become the main centerpieces of the gardens that I have designed.

I have gone on tree-hunting expeditions up to northern California and walked amongst these ancient giants and picked out certain character trees for specific projects and it is like strolling in a living art gallery when selecting the one-of-a-kind olive tree and I return all charged up again from that arboricultural and spiritual experience with the ancient ones.

It is always important when placing trees of any type out into a garden setting to have the right tree in the right place. And this is very important if you are using any of the fruiting types of olive trees.

“Fruiting trees?” you ask. “Aren’t all olive trees fruiting?” No, and I will describe those later.

Plant olive trees in full sun and away from sidewalks, hardscape and pools to avoid stains from fallen ripe fruit, for they can be messy if you don’t harvest the fruit.

Non-fruiting trees are available which can be planted in areas where the fruit may be a problem. Some of those cultivars are Swan Hill and Wilsoni, which bear little or no fruit.

Olive trees look best when grown in deep, rich soil, but they will also grow in shallow, alkaline or stony soil and with little fertilizer.

Olive trees can be thinned with skillful pruning shears over the years to allow the wonderful internal branch structure to be viewed as a work of art created with proper and diligent tree care.

There is one little olive tree that needs attention as well, called “Little Ollie,” and grows to about 12 feet or so in time. This little olive tree can be used for some of the smaller garden settings and it’s great to espalier on a hot stucco wall or even used to screen a chain-link fence.

“Little Ollie” can also be used as an ornamental hedge with directional pruning and it bears almost no fruit. I have used them in red Italian terracotta containers on patios and they can become lovely container plants in the right place.

There are so many varieties with so many different qualities in their selection and the following is just a few of the cultivars in the trade.

• Ascolana bears fruit, small pit

• Majestic Beauty is airy and fluffy looking and suitable as a specimen tree, almost no fruit

• Manzanillo is a commercial grove type and a specimen landscape tree

• Mission is a commercial-grove type also used in landscaping

• Sevillano, another commercial-grove, is also sold as a landscaping specimen

And there are many, many more.

The olive fruit is a green drupe botanically, becoming generally blackish-purple when fully ripe. A few varieties are green when ripe and some even turn a shade of copper brown.

The cultivars vary considerably in size, shape, oil content and flavor. Raw olives contain an alkaloid that makes them bitter and unpalatable to eat right off the tree. This is when the process of curing and treating the olive fruits goes into motion.

There are several classical ways of curing olives. A common method is the lye-cure process, in which green or near-ripe olives are soaked in a series of lye solutions for a period of time to remove the bitterness and than transferred to water and finally a mild saline solution.

The marinating process can be quite involved, but more and more mini farms are springing up in California producing organic olives and homemade high-quality virgin olive oils. Olive oil is titled “virgin” after extensive pressing and curing of the fruit.

Fallbrook, with its dry summers and rolling hills, became an ideal location at the turn of the century for the production of olives as a viable agricultural tree crop prior to the avocado industry.

The Fallbrook olive industry was booming in the 1900s and continued for some decades here in north San Diego County with patches of olive groves dotting the landscape.

The Loma ranch in Fallbrook had a large olive orchard with its own olive oil press and bottling plant, producing approximately 15,000 gallons of high-grade olive oil annually until 1919.

The Red Mountain Ranch was another of the large olive oil producers on the east side of Fallbrook and had its own processing plant as well.

The hybrid virgin olive oils that are available today are like the fine couture industry and olive oils have become a mainstay in the culinary trade to add just that special flavor to a variety of foods.

With the current water cutbacks in the local area, olives once again might return as a viable tree crop under the current availability of water and the ideal climate for growing these beautiful ornamental and fruit-bearing trees.

So whether you are looking for that fabulous artistic shaped olive tree to anoint your garden or looking for an alternative potential tree crop to be grown, consider the wonders of the olive tree. “Viva olivos!”

For those of you who would like additional news on olives, send me a self-addressed envelope and I’ll pass along some added information.

Certified ISA Arborist Roger Boddaert, a horticultural landscape designer, can be reached at (760) 728-4297 or PO Box 1806, Fallbrook, CA 92088.