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cold-hardy citrus in the Pacific Northwest - update Dec 2019

socalnolympia
last year
last modified: last year

This is the latest update from my cold-hardy citrus collection growing outside in the Pacific Northwest. Olympia, WA.

If you check the latitude coordinates, you'll find this is actually just a tiny bit farther North than Duluth, Minnesota, or Quebec City, Canada.

However, the climate here is far more mild than those places, because of the winds sweeping in from the Pacific Ocean.

The Japan current warms the water by just a few degrees out in this direction, but it is mostly not that. The main reason has to do with the direction of the Earth's spin. When temperate latitude convection air currents move north, they get apparently deflected to the east because the surface of the Earth is spinning at a faster speed towards the equator than towards the poles. (These are known as the Westerlies). This air moves over the Pacific Ocean onto land on the West Coast. The water is cold, but still much warmer than the land temperatures would otherwise be. Another big factor is that, ironically, because the Pacific ocean water always remains cooler, it does not drive storm systems as much as on the East Coast. Storm systems rotate in a counter-clockwise direction, which can pull colder continental air from further north. On the East Coast, there exists both the influence of warmer water coming from the Gulf of Mexico and, off the coast of New England, the Labrador current which brings cold water from the Baffin Bay in the far North - a little bit of the worst of both worlds.

Back to the climate here, this is classified to be in USDA climate zone 8. More specifically, zone 8a here (though I suspect it is closer to zone 8b than 7). The Summers are hot and dry, but tend to be shorter and do not last as long as they do further south. Because of the more farther northern latitude, the length of daylight is noticeably longer in the Summer, but the length of Winter is also noticeably longer. Cooler temperatures last for nearly half the year, where it is not warm enough for citrus to put on growth. It remains pretty constantly cool to cold, but rarely gets very cold.

I am showing these pictures taken as of December 22, 2019 so you will be able to see how the plants looked going into Winter, and then be able to compare with updated pictures later, to see how much cold damage was inflicted and how much the plants were able to recover and grow.

Most of these are some pretty rare citrus varieties (species and hybrids) which you will not be able to find available for sale. Eating quality of these varieties is not as good as the normal varieties sold at a typical supermarket, but that's a trade-off if you are trying to grow citrus this far north, since obviously most regular varieties would not be able to grow in this climate.

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