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Oregon Olive Trees™ |
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Oregon Olives |
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Think global - buy local. |
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Oregon Olives |
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Oregon Olive Oil |
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Oregon Olive Trees |
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Trees for Sale |
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Introduction |
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Planting |
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Growing |
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Cultivars |
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Leccino (2) |
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Winter killed roots This is how I learned that the conventional wisdom that olive trees in the ground are hardier than olive trees in pots is correct. These were trees I was saving for replanting or grafting, but every single one of the trees in black plastic two gallon pots had their roots winter killed. The symptom is just what you see: crispy dead brown leaves that still cling to the tree. |
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Winter killed tops Trees planted in the ground were far more likely to instead have just the tops killed back, more or less, but with the roots still alive. Here is a picture looking down a row of young Frantoio trees (fall planted, last fall). The bad news is all top growth was lost; but the good news is every one of these trees is still alive and re-sprouting from the roots. |
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Moraiolo |
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Tractor “Road Kill” This one I roto-tilled over with the tractor when I was removing the spring cover crop. Oh well! It is coming back as my first true multi-trunk olive tree!
Winter kill - the bottom line
We lost right around 10% of the olive trees in our groves to the December 2008 storms. Some other interesting facts:
- the only trees in the ground for two or more years that died also had fairly extensive rodent damage to the trunks.
- about 75% of the olive trees in pots died. Of course, these were all young trees too, since the largest pots were two gallon size.
- in general, it would be hard to say which cultivars are cold hardier, using tree death as the determinant. Some that are not supposed to be cold hardy, like Koroneiki and Manzanillo, did at least as good as the average.
- the only cultivar that had a high death rate was Taggiasca, with 5 out of 10 trees dying. I guess I wont be going out to the local Benedictine Monastery and trying to convince them to use Taggiasca olives to make traditional Benedictine-style olives any time soon!
- the storms killed both our Windmill Palms (Trachycarpus fortunei, widely considered to be one of the hardiest palms). So, I’d have to say that this is evidence that olive trees in general are slightly hardier than the hardiest palms. |
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Living on the Edge - Growing Olive Trees in Oregon (continued) |
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Winter 2009 / 2010 Weather Update
As those of you in the area know, we had yet another brief spell of extraordinarily cold weather in December 2009. Unlike the winter storms of December 2008, this time the cold was caused by radiative frosts. These happen on winter nights with low humidity, no cloud cover and calm weather; heat simply radiates away into space (it isn't commonly mentioned, but the "greenhouse gas" that contributes the most to global warming is water vapor). If you want to understand the differences between advective freezes (Dec 2008) and radiation frosts (Dec 2009), here is a good link to follow:
Frost / Freeze Protection for Horticultural Crops
Our min/max thermometer recorded 10 F in the olive grove; the nearest official weather station (the McMinnville Airport) reported temperatures down to 7 F. Here is a graph of that station's data from Dec 6, 2009 until Dec 12, 2010 (note the time spent significantly below 10 F must have been very short, as those data points are not show on the time compression shown here): |
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It could have been worse. The record cold temperature for McMinnville, OR is -24 F, recorded in 1919. Here is a graph showing 2009 temperatures (red and green) as compared to the all time records: |
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Winter 2009 / 2010 Final Damage Update We have essentially three different projects / groves; let's consider them from oldest to youngest.
The Reken Estate was our original field planting in the spring of 2006, when we didn't know of -any- olive trees planted in Oregon. Ten cultivars (Frantoio, Santa Caterina, Pendolino, Amfissa, Maurino, Itrana, Leccino, Picual, Coratina and Arbequina) were planted in a 28' hexagonal pattern, meant for minimal input dry farming. Although two trees did die this winter, the remainder of the trees showed almost no damage, and all appear poised to set fruit this year.
Reken Estate, 07/02/10 (intercropped with barley, oats and wheat): |
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Late spring 2010 photos have been added to these cultivar pages:
Aggezi Shami, Aglandau, Amfissa, Ascolana, Azapa, Barouni, Boutellian, Chetoui, Gaidourelia, K18, Koroneiki, Lechin de Sevilla, Manzanillo, Mission, Mission Leiva, Nocellara del Belice, Oeslati, Salome, Saiali Magloue, Santa Caterina, Tanche and Verdale.
You can see photos of the same trees from year to year and season to season, including the effects of the past two winters.
Compare the damage in this Oregon freeze to the report of a 1990 freeze in California:
Freeze damage and coldhardiness in … the 1990 freeze
On a slightly humorous note, if you believe the web posting below, you would think north west Oregon has only dead olive trees, due to the extreme cold:
Got the Right Climate for Growing Olives?
While this climate advise is no doubt useful in California and other traditional olive growing regions of the world, it provides little insight into conditions here in Oregon. |
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The Leccino in the foreground below is the same one portrayed in the story of the December 2008 storms. It has fully recovered, except it has sort of been compacted. All branches lost their tips, so apical dominance was cancelled all over the tree; it sort of just got like a hairball (there is an orange Kubota tractor parked behind it - I can see a few pixels of orange… can you?).
Reken Estate, 07/09/10: |
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Picual was planted in that early grove as a "dark horse" to win a Gold Medal extra virgin olive oil prize upon being grown here in Oregon (hence the name "Dark Horse Field Blend" above). So far, so good!
Reken Estate, 07/10/10: |
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If these about to open blooms are any indication, Picual ought to be just dripping with olives this year!
Reken Estate, 07/10/10: |
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But I'd have to say this Coratina tree takes the "Olive Blossom 2010" prize this year!
Reken Estate, 07/10/10: |
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I think the message from the Reken Estate is: if Oregon can get some olive trees growing in the ground for just a couple of years, temperatures as low as 10 F (full USDA Zone 8) is do-able! Of course, don't count your olives while the tree is blossoming: this falls harvest will have another chapter to add to the story!
Our next project is Kathy's Grove: a experimental production grove of Tuscan olive oil trees and table olive cultivars from around the world. The 2 gallon size trees were mostly planted in the fall of 2008, right before the December 2008 winter storms. The grove took major damage (see our Introduction page) resulting in about 10% tree loss in 2009; and lots of damage to the remaining trees. Of the trees that lived through the December 2008 storms, about 20% died in the December 2009 radiative frost event. The one - two punch KO'ed them.
Interestingly, of the 10% of the grove that were replants, not a single tree died (this will become even more significant when you see the results of the last of our "groves"). The message here: we are on the edge of where it is possible to grow olives, and if events conspire to drain the trees of energy, any subsequent negative effects will be multiplied.
Kathy's Grove, Tuscan olive trees (e.g. Lucca in the foreground), 07/04/10: |
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There were some trees planted at Kathy's Grove from the same batch as the initial plantings at the Reken Estate. These trees, in particular the Leccino in the back, are always our top yielding trees (Kathy's Grove was soil amended according to soil analysis, and then heavily cover cropped for a year).
Kathy's Grove; Tuscan olive trees 07/04/10: |
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Our third "grove" is actually our tree nursery. Coming through the 2009-2010 winter, this was mostly small olive trees (less than 1 gal), with a fair amount of 1 and 2 gal trees. The sad news is virtually 100% of our cuttings / transplants (size less than 1 gal) were killed. Ouch. That was thousands of trees. Of the 1 gal and 2 gal plants, perhaps 50% were killed.
I find that extremely interesting. Putting the data from Kathy's Grove (no loss on the very same plants as lost 50% or so in our nursery) with the symptoms of the dead plants in the nursery - it is the olive tree roots that died as a result of the 10 F winter. This (of course) caused the rest of the plant to die.
And with that conclusion we all can do something! Winter mulch, deep winter mulch may be able to prevent some of the field tree death in the future. Caveat: to help the soil warm in the spring, the mulch should be removed or dispersed before spring growth should start.
As for our nursery, the conclusion I draw is that Oregon Olive Trees needs a greenhouse. |
