Rice is cultivated throughout Japan. In Hokkaido, Japan's northernmost island, hardier varieties are grown. In Honshu, the Japanese mainland, varieties such as koshihikari are grown. The rice seeds are first soaked in water, then planted into trays under cover before being planted out when they have become big enough. Rice fields cover many hillsides in rural Japan. Farmland is limited because so much of the country is mountainous.