The word “research” is a part of the title of the Oregon State University North Willamette Research and Extension Center (NWREC) in Aurora, Oregon, and it is certainly worthy of it. My dealings with this research center have just touched the tip of the iceberg as to the depth of research being carried on there.

Neil Bell, a semi-retired community horticulturist with Oregon State University Extension, has been one of the primary researchers whose work I have followed. Over the years, his research has included trials of Arctostaphylos, Phlomis and Ceanothus, just to name a few. Now it includes olive trees.

Testing for suitability

The purpose of Neil’s trials is to broaden the palette of plant selections that may be new to our area and perhaps have not yet been readily available locally. His research has focused on testing plants that may have been considered marginally winter hardy or may not withstand the summer’s heat for a home gardener.

Within a plant genus, which can contain from 1–1,000 or more species, there can be great diversity as to a plant’s requirements. Such diversity is, in many ways, very similar to the great diversity here in the Pacific Northwest with our many microclimates.

In 2019, unrooted cuttings of olive trees arrived at NWREC. It was a mix of species, cultivars, varieties and some with just numbers. Because of this mix, Neil refers to the collection as “accessions,” which was a new word to me that I had to research.

The best definition that is meaningful to this topic is “a distinct, uniquely identified sample of seeds or plants, that is maintained as part of an active collection.” There were 116 accession cuttings and the majority had four cuttings of each.

Two years after their arrival, in 2021, the rooted cuttings were planted in a large, open field at NWREC.

Survival of the fittest

When plants go into this open field, there is no protection from the elements. They are exposed to wind, rain, snow, cold, and heat. The newly planted olive trees are irrigated at the time of planting and then watered on an as-needed basis.

This trial is a true survival test. One of the most crucial weather situations occurred in January 2024, with two nights of 15 F temperatures. While this resulted in some devastating damage to some of the trees, in some ways it was a good test of which trees survived with no damage, and which had very little damage.

This trial was a test to determine if olive trees can not only be grown as a commercial crop in the Willamette Valley, but also as a shrub or tree in a home garden setting. With their gray-green evergreen foliage, they can make a striking specimen planted in a home garden, either in the ground or in a large pot. Being native to the Mediterranean region, they grow well in areas with hot dry summers.

In the past few years, there have been a limited supply of olive trees available at local garden centers, with Arbequina as the most prevalent. Sean Hogan, (Cistus Nursery, Portland, Oregon), has been a strong advocate for olive trees. His website lists Arbequina as “self-fertile and fruits at an early age, heavily used for oils. Wonderful for small gardens or containers.” Another one is Leccino, which has performed well in the NWREC trials.

Suited for Oregon

For home gardeners, Neil suggests planting olive trees in the sunniest location available. Good drainage is essential. Neil also commented that he has noted that the trees seem to withstand cold winter temperatures better if they are multi-trunked rather than grown as a standard with a single trunk. Just thinking of pictures of olive trees growing in the Mediterranean area, the trees are almost always multi-trunked.

An update from Neil on Saturday, November 8, reported that the first batch of OSU olive oil from the olive harvest was produced!

“We picked (with the invaluable aid of our crew of volunteers) 707 pounds of fruit, which after weight and fruit size data were collected, were then taken to the mill,” Neil said. “The oil was produced by Beth Wendland of Coyote Hill Nursery, who processed the fruit in her Mori-Tem olive mill. In general, the fruit was sorted in totes according to level of ripening and they were milled that way.

“Greenish-yellow fruit were milled in batches and purple-ripe fruit were milled in separate batches to allow for some very broad comparisons on the effect of stage of ripeness on oil characteristics. The yield from this was 11 gallons of oil. The oil is still to be filtered by Beth, after which we will receive it for bottling. We are all very excited about this outcome and grateful to our volunteers, as well as Beth and partner Bruce for this service!”

The information from Neil and the crew at NWREC can be invaluable for a garden center. Gardeners are aways searching for something new and different and an olive tree might be just what they need. They can be excellent as container plants and with our increasingly hot summers, they might be just perfect in that hot and sunny spot. Just think of the displays that garden centers can design to show off these Mediterranean beauties!

From the January 2026 issue of Digger magazine | Download PDF of article