Challenging climate
The decision to select Koshu stems initially from its long-time presence in Japan, along with the variety’s suitability to the country’s climate – a challenging one for cultivating grapes because of rain during the growing season. The main vine-growing areas of Japan are, after all, based in a sub-tropical climate, albeit relatively dry examples of such prevailing weather systems.
Koshu is believed to have arrived in Japan via the Silk Road from the Caucasus around 1,000 years ago, but it wasn’t until the 1870s that the grape was used to make wine – it had previously been grown for eating. But the use of Koshu is inextricably linked to the birth of the Japanese wine industry, because the country’s first bottles of wine were made with the grape, and hailed from the city of Kofu – in the heart of the Yamanashi wine region, where to this day, 95% of all Koshu is grown.
It is a hybrid grape, believed to have originated naturally by a crossing of the European Vitis vinifera and an Asian Vitis species. It excels in Japan’s humid conditions, and produces wines of finesse. In 2009, Koshu of Japan was founded to champion the grape, and in 2013 it was recognised by the OIV, adding greater impetus to Japanese wine producers to promote the variety more widely.
There is something so distinctly Japanese about it too. In part, this relates to its appearance. With beautiful deep-pink berries, it complements the slightly paler shades of the cherry blossoms that Japan is so famous for.
Not only that, but its primary growing area, Yamanashi, is overshadowed by the perfectly cone-shaped, snow-capped, volcanic wonder that is Mount Fuji – the most powerful visual symbol of Japan. Combine the translucent pink of Koshu with the instantly recognisable background of Mount Fuji on a clear day, and you have an image so striking, any wine lover will not only remember it, but will want to try the product featured within it.
Then there’s the growing technique. In keeping with Japan’s reputation for precision in technology, the country’s viticulturists go to extraordinary lengths to protect the Koshu grapes, choosing to train them high in pergolas, improving airflow around the bunches, while also shading the grapes from temperature extremes. They also protect the Koshu grapes from summer rainfall with little wax paper hats stapled together above each bunch, ensuring that the water doesn’t get inside the bunches. Otherwise, the water might start the spread of rot, which would spread rapidly in this warm and damp climate.
It’s an effective, if quite expensive technique, not used anywhere else in the world. As for the rainfall that does wash onto the ground, the free-draining soils of the Yamanashi area, many of them volcanic in origin, ensure that the berries themselves don’t swell too much, preventing the resulting wines from suffering from dilution.
Nevertheless, Koshu-based wines are delicate. Naturally around 11% ABV – and rarely above 12% – they are never tiring to drink, or forceful in character, but deliver something subtly intriguing. As we reported in an article last month that focused on introducing the Japanese wine scene as a whole, the wines made from Koshu tend to have a combination of flavours, from citrus to yellow fruit, and in general, to draw comparisons with well-known European whites, have some of the flavours of Muscadet, with its freshness and breadiness – the Japanese tend to give Koshu relatively extended lees contact – but also Albariño, with its lime-acid and peach fruit. Koshu also has something more unique, in the form of a gentle salty note, as though someone has added a drop of soy to the glass.
