Regional Gardening Reports :: National Gardening Association

In the Garden:
Northern California Coastal & Inland Valleys
December, 2011
Regional Report

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Olives trees are shapely, long-lived, and perfectly suited to our climate -- but you have to love olives!

The Truth About Olive Trees

Do you want the truth about olive trees (Olea europaea)? Here it is; If you don't want olives, don't plant olive trees. Yes, I know that they are very sculptural, and their gray bark enhances a dark landscape. I know that the multiple trunks are handsome, and I know that the silver foliage provides an airy feeling. Yes, they are perfectly suited to our Mediterranean climate. However, if you don't want olives, don't plant olive trees. I know this from experience.

Olive trees thrive in deep rich soil, but they are equally at home in alkaline or shallow soil, being native to the dry, rocky hills and mountains of the Mediterranean region. They are very drought-resistant and thrive in areas with hot, dry summers. Sounds perfect, right?

The grounds of Sunset Magazine and Books in Menlo Park were spangled with 43 beautiful olive trees that had been transplanted as mature trees to the property at great expense. They thrived in the heavy clay soil, and because they were so happy in their environment, produced an abundance of fruits. Therein lies the rub.

The patios at Sunset Magazine are made from expensive terra cotta tiles. Tiles plus olives equal stains -- dark stains that were impossible to clean. Great lengths were gone to in order to prevent the trees from dropping their abundant crop all over the patio tiles.

Every spring the head gardener tried to gauge when the trees were in full flower. At that point, the entire garden team arrived very early in the morning to cover or move every container or flower bed under each of the many trees. Once the surrounding plants were protected with plastic sheeting, the head gardener came in to spray with Florban, a product used to inhibit fruit production by interfering with the flowering of the tree. This type of product is usually used on liquidambar trees to discourage the production of those little "ankle biting" balls.

Once the olive trees had been sprayed, they were given an hour or so to drip dry before the plastic covers were removed, the pots set back in place, the patios swept and everything was once again presentable for public viewing.

The problem was that spraying only made the olive trees mad. Instead of the usual process of natural selection causing most of the flowers to drop, leaving only the strongest to develop into fruit, a secondary crop of flowers bloomed after the treatment. Left to mature, this second crop of flowers, although smaller, produced thousands and thousands of seedy little olives. I think the trees were trying to overcome what they perceived as an attack and produced more fruit to ensure survival. So, instead of a few large fruits which would normally be carried away by hungry birds or people, the trees produced as many seeds as possible. Those pithy little fruits dropped in abundance all over the tiles in spite of our best efforts. Many man hours were spent sweeping up and throwing away zillions of tiny olives.

There are varieties of olive trees that are supposedly fruitless and are sold that way. However, they all eventually revert to their natural state, so don't trust the claims.

With and average life span of 500 - 900 years, and some living to 2,000+ years old, an olive tree is going to be with you for a very, very long time. So, my advice to you is; if you don't want olives, don't plant olive trees.

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