When the weather becomes colder or more yin in autumn and winter, leaves die, and the energy of plants descends to the root system. Root vegetables, such as turnips and radishes, are hardier and more concentrated as a result. When the atmospheric and vegetal energy begin to rise in spring, and the weather becomes warmer, or more yang, new shoots, which are yin, start to appear. Summer vegetables, such as cucumbers, are watery and perishable. Fruit, which is very watery and sweet, ripens when the yang energy reaches its peak in late summer.
Yang plants warm the body in the colder months and activate the metabolism, while yin fruit and vegetables have a cooling effect, slowing down the body’s metabolism when it’s hot. To maintain balance with the shifting atmospheric conditions, one should eat plants that grow in season, with their complementary yin-yang energy.
Grains can also be classified along this continuum. For instance, millet and buckwheat are warming and are recommended for regular use in autumn and winter, whereas barley, corn, and long-grain rice are cooling and should be eaten more in spring and summer.
(figure from The Book of Macrobiotics, Michio Kushi)