Olives
The Willamette Valley is now the northernmost region in the US where olives (Olea europea) are grown commercially.
The biggest hurdle to establishing groves is that the trees lack full cold hardiness when young and are susceptible to dying during cold snaps (lower than 15°F). Once established, though, the trees are perfectly hardy in our climate and can handle snow and ice with ease. The first trees planted here were brought up from California, and subsequently died in cold weather. Now that varieties sourced from more northern regions of the world are being planted, we are seeing the beginnings of a new olive-producing region.
A very new industry, there is a strong push to establish olive groves and olive oil processing in the region. OSU is currently trialing several varieties of olives and growers are steadily planting more trees in the Willamette Valley.
Since it’s a new industry and a premium product at this time, I try to treat our olive oil as a special product and use it in ways that highlight it. I have not been able to source local table olives, but local olive oil is readily available from Durant Mill, which as of 2023 is the only processor in Oregon. Currently, about 100 acres are currently under cultivation by about a dozen growers. At this time, production is limited to the Willamette Valley and the Sacramento Valley.
Olives are originally from an area near Turkey and spread during antiquity to the rest of the Mediterranean Sea. They’re now grown around the world, even in places such as Brazil and Azerbaijan.
Species and varieties
Olives
Olive (Olea europea)
‘Frantoio’
‘Leccino’
‘Ascolano’
‘Arbequina’
‘Arbosana’
‘Koroneiki’
‘Mission’
‘Brava Gallega’
‘Mansa de Figueiredo’
Selected varieties
There are countless varieties that may be viable in our region. That said, some have been tested more than others, and some are from regions that are more similar to ours. I’ll be focusing on those.
For Italian olives, the Tuscan hills are a notable region to examine. Low temperature records for Tuscany are comparable to those in the Willamette Valley. In addition, they seem to have had more extreme low temperature events in the past 100 years than us, so varieties that have succeeded there should do especially well in Oregon. Many Tuscan olive oil groves were severely harmed by snow and ice in 1985, with 90% of the trees affected or outright killed. Those trees were mostly replanted with ‘Frantoio’, which is known for its resistance to cold.
Another Italian region of interest is alpine South Tyrol near Austria, which might very well be the northernmost olive growing area in the world. Information is limited, but local varieties include ‘Casaliva’, ‘Grignano’, ‘Favarol’, ‘Frantoio’, ‘Pendolino’, ‘Leccino’ and ‘Leccio del Corno’.
As for Spanish olives, the ‘Arbequina’ variety is the most common. ‘Mission’, a Californian variety which was originally brought by Spaniards in the 1700s, is another common one. I suspect that more Spanish varieties could be sourced from northern Spain, in particular, from Galicia, which is an area that has some of the greatest similarity to the Pacific Northwest in the world. Galician olives were eclipsed by southern Spanish production long ago and have been largely abandoned, but recent research has been carried out on some old varieties, such as ‘Brava Gallega’ and ‘Mansa de Figueiredo’. There are many others.
‘Frantoio’ is a clear winner for our region, this one has excellent cold-hardiness (down to 0°F once established). It is currently being tested by OSU, and has received praise from several of our local nurseries (Cistus, Xera, One Green World).
Highly regarded in Italy, it produces a dark green, aromatic and herbaceous olive oil. Personally, I’m a big fan of the robust flavor profile. The fresh oil is generally quite strong in flavor and is often blended with other varieties. ‘Frantoio’ olives are usually pressed for oil but are occasionally made into table olives.
‘Leccino’ is currently being trialed by OSU. Many sources seem to state that this tree is only hardy to about 20°F, but given that it’s a commonly grown variety in regions such as Tuscany and South Tyrol in Italy, I doubt that this is truly accurate, and I’m confident that it should be able to handle lower temperatures. ‘Leccino’ olives are often made into table olives. The oil is mild and sweet.
‘Ascolano’ is also being trialed by OSU. In addition, this one is highly rated by Cistus Nursery and is likely to have similar cold-hardiness to ‘Leccino’. ‘Ascolano’ trees produce very large olives, which are often used to make an Italian snack called “olive all’ascolana”, in which the olives are pitted, stuffed with seasoned meat and then battered and fried. ‘Ascolano’ olives produce a light, fruity olive oil.
These olives are currently grown commercially in the northern Sacramento Valley.
‘Arbequina’ is a northern Spanish olive can be found planted all over Portland. ‘Arbequina’ olives are the most common olive oil variety in the world. They produce a mild fruity olive oil. Compared to other olive oils, it has a shorter shelf life.
The olives themselves are small, and I’ve only been able to source cured ones from Spain, but they’re absolutely delicious table olives.
‘Arbosana’ is a Spanish variety commonly grown alongside ‘Arbequina’. Produces a robust, fruity, and slightly peppery olive oil. Besides ‘Arbequina’, this is one of the more commonly grown varieties in Northern California.
‘Koroneiki’, a Greek variety, is said to be less cold-tolerant than other varieties, but is available as olive oil from Durant Mills. Cold-hardiness is still being tested, but it has performed well in commercial groves. I suspect this variety is best suited to the warmer microclimates or areas of our Northwest region. ‘Koroneiki’ produces small olives that make an excellent fruity olive oil.
‘Mission’ olives were originally planted and spread by Spanish colonists and missionaries in the late 1700s. They were likely brought up from Mexico and are thought to have originated from a Moroccan variety.
Although ‘Mission’ olives have not made up the majority of California’s olive production since the late 1800s, Butte County remains one of the top producers of the variety. They are the cold-hardiest olive produced commercially in California.
As table olives, they’re often encountered as the over-processed canned black olives found in the US, but they do actually make a good table olive when brined properly.
Cooking with olives
Olives ripen in mid-fall in our region.
Table olives
Producing table olives involves debittering the olives. There are three methods of doing this: salt-curing or drying, fermenting in brine, or curing with lye. Debittering is done to remove the bitter glycoside “oleuropein”.
Salt-cured/dried: processed by curing in salt or drying and then storing and hydrating in oil
Fermented: fermented in a brine solution.
Lye-cured: lye is used to debitter the olives, which are then rinsed repeatedly and put in brine.
After this, olives can be processed further; they can be pitted, stuffed, cracked, or flavored with spices and herbs.
