I don’t want to bump an old thread, but I’m looking to plant some Hojiblanca here in Olympia, WA 8a and this thread came up.
I went ahead and translated the article shared by Patanx, which was a great read. I might now have to get a couple different varieties! My elementary translation is below, for those who want the gist of what it says.
Side Note: if anywhere knows of a way to buy Belica olive trees and get it here to the States, let me know!
Thousands of years ago, the Romans, in their empire, which at that time extended far into the north, attempted to find olive varieties that could best cope with local conditions wherever possible. Today, we know that most of the approximately 2,000 olive varieties are the result of Roman selections, but also of advanced civilizations before them. Few are aware that a vast gene pool exists here—with significant differences in winter hardiness, but also in the tolerance of varying rainfall, weather conditions, and subsoil. Today, only a few varieties are still cultivated, and since the olive-growing regions are located far in the south of Europe, winter hardiness is a negligible criterion, less important than yield, flavor, and disease resistance. However, at the northern edge of olive cultivation in Europe, we find the most interesting varieties, which in recent years have also been shortlisted for cultivation in Europe.
THE RIGHT VARIETY
The old varieties from Galicia in northwestern Spain demonstrate the unusual types of olives that exist. Until about 500 years ago, there was commercial olive cultivation there, with many indigenous varieties (for example, ‘Brava’, ‘Mansa’, or ‘Dócil’) that were adapted to fog, humidity, and high rainfall. For political reasons, olive cultivation was suddenly banned at that time, and the crops had to be cleared. Today, only a few of these moss-covered, centuries-old olive trees remain, hidden in the damp forests of the mountains of Galicia. Resourceful landscape designers have dug up some of these olives in Galicia and planted them in stylish villas on Mallorca – unfortunately, with the result that these old trees withered hopelessly after a short time
With this example, I want to illustrate how important it is to use the right variety for gardens in Central Europe. The run-of-the-mill olive from the hardware store freezes to death at temperatures below -10 degrees Celsius and in permafrost. Even mass-produced olives from nurseries in Mediterranean countries are hardly winter hardy enough for planting attempts here. In particular, the centuries-old specimens with the gnarled trunks available commercially mostly come from Spain, by far the largest olive-growing country in the world. They all grow in regions where temperatures almost never drop below -10 degrees Celsius and permafrost is a foreign concept. To get hold of the truly winter-hardy varieties, you have to look at specialized nurseries further north
A LONG ROAD
My experiments with olives began almost 20 years ago. At first, I tried varieties from Spain that were inexpensive. There were only setbacks. Contrary to popular belief, Spanish varieties such as ‘Hojiblanca’, ‘Picual’, or ‘Arbequina’ are far too sensitive for garden cultivation here. Even varieties from Italy that are also cultivated in Tuscany, such as ‘Frantoio’, ‘Leccio’, or ‘Cipressino’, are not hardy enough for long-term cultivation. Even the wild olive Olea sylvestris did not prove sufficiently winter hardy
After numerous visits to northern Italian nurseries and discussions with their owners, I slowly found varieties that seemed very interesting for cultivation here. I was explained several times that the substrate is particularly important for olives: The olive needs the worst soil available—by which they meant dry, stony, and nutrient-poor; only then can it develop its full winter hardiness.
In the Po Valley, even in the past, olives in nutrient-rich soil regularly froze to death in colder winters. Only on the edge of the Alps and on stony ground or slopes with terraced cultivation and stony ground was commercial cultivation possible
moderate olive cultivation in northern Italy. Now I finally realized what I had also experienced in relatively mild winters: The young olive trees still had some green leaves after the winter, but the bark cracked at the soil level, and the entire tree subsequently died in the spring. Therefore, moist and nutrient-rich soil must be avoided at all costs when growing olives.
PASSED ALL HARDNESS TESTS: ‘MORCHIONE’
The first supposedly legendary winter-hardy olive variety I used as a test plant was ‘Morchione’ from Tuscany. Supposedly, all offspring come from a tree that survived -20 degrees Celsius in the mid-1980s with green leaves and no damage. I planted ‘Morchione’ in 2012 in a planting hole filled with plenty of gravel, and in its first winter, it had to endure -14 degrees Celsius. While other varieties, such as ‘Frantoio’, froze to the ground that same year, ‘Morchione’ actually survived with green leaves and only slight damage to young shoots.
To this day, ‘Morchione’ is one of the hardiest varieties tested in my garden. The winter of 2017, with the coldest January in 30 years, several weeks of persistent frost and strong storms, with temperatures reaching -15 degrees Celsius, was a Another endurance test for the varieties planted at that time. This was followed by the otherwise mild winter of 2018, which, however, ended with a low of -16 degrees Celsius on the morning of March 1. I’ll say it right away: ‘Morchione’ survived all these winters with green leaves, while ‘Frantoio’, by comparison, was completely frozen after these winters and could no longer regenerate from the base.
FURTHER SUCCESSFUL EXPERIMENTS
In 2016, I began planting olives on gravel hills. Since my property is in the Seewinkel region, the terrain is actually unsuitable for olive cultivation. However, the substrate on the gravel hills is perfect. In an initial test, the ‘Bianchera’ variety performed very well, so I began planting several trees of this variety.
‘Bianchera’, known under the name ‘Belica,’ was the olive of the Austro-Hungarian Empire because it is the standard variety in Istria, and this variety produces a particularly high-quality olive oil. Empress Elisabeth supposedly only used olive oil from this variety. Adapted to the extremely cold winds, the Bora, it is also particularly hardy in my area and even survived the harsh winters of 2017 and 2018 with green leaves after replanting. Relatively hardy varieties, the ‘Leccino’ from Tuscany, had either lost all their leaves or froze to the ground that same winter.
It is important to remember that the winter hardiness of olives is very closely linked to the weather. Some varieties tolerate fog poorly, others wet winter weather or persistent frost less well. With increasing global warming, it will be necessary to test which varieties are better suited to which regions
The olive from the southern edge of the Alps in Italy is ‘Grignano’. Tests have shown it to be very hardy and it probably tolerates higher rainfall better. ‘Maurino’ is also remarkably hardy. For those who only want to use the olive as a garden design element, I would recommend ‘Morchione’. However, if someone also wants to produce olive oil in the future, ‘Bianchera’ is the first choice. For table olives, the hardiest variety is ‘Ascolano’, which unfortunately cannot tolerate temperatures below -14 degrees Celsius. For a successful harvest, pollinator varieties are recommended. However, many of the optimal pollinators have low frost hardiness.