The Koshu grape vine is robust and treelike, difficult to plant in compact vineyards. Thus recent years have seen experiments with vertical shoot positioning in addition to the traditional trellis method. Long cordon pruning has also been tried as an alternative to the traditional Japanese pruning technique. Significant advances have been made in limiting production and crown management technology. For winemaking as well as viticulture, international experts have been invited to Japan to contribute their expertise. Improvements in winemaking have resulted in production of authentic, dry wines which retain the delicate bouquet and flavour of the Koshu grape.
The Koshu grape is strongly disease-resistant and has had centuries since its introduction to adapt to the terroir of Japan. It is grown in vineyards totaling 480 hectares, with 95% of total production grown in Yamanashi Prefecture. The Koshu grape belongs to the same Vitis Vinifera family as European grapes and has long been part of the Japanese diet. The skin is thick and pinkish-grey. The clusters are long and the fruit of medium size. A distinctive and refreshing bouquet and a nicely balanced acidity are among its distinctive characteristics.