The great variety and luxuriance of Japanese plant life is mainly caused by the heat and moisture of Japanese summers. More than 17,000 species of flowering and nonflowering plants are found, and many are widely cultivated. The white and red plum and the cherry bloom early and are particularly admired. The Japanese hills are colorful with azaleas in April, and the tree peony, one of the most popular cultivated flowers, blossoms at the beginning of May. The lotus blooms in August, and in November the blooming of the chrysanthemum, the national flower of Japan, occasions one of the most celebrated of the numerous Japanese flower festivals. Other flowers include the pimpernel, bluebell, gladiolus, and many varieties of lily. Few wild flowers are found, because the small area of arable land is heavily farmed and permits little space for uncultivated vegetation in the plains.

The predominant variety of Japanese tree is the conifer; a common species is the sugi, or Japanese cedar, which sometimes attains a height of 46 m (150 ft). Other evergreens include the larch, spruce, and many varieties of fir. In Kyushu, Shikoku, and S Honshu subtropical trees, such as the bamboo, camphor tree, and banyan are found, and the tea plant and wax tree are cultivated. In central and N Honshu the trees are those of the Temperate Zone, such as the beech, willow, chestnut, and many conifers. Lacquer and mulberry trees are cultivated extensively, and the cypress, yew, box, holly and myrtle are plentiful. In Hokkaido the vegetation is subarctic and similar to that of S Siberia. Spruce, larch, and northern fir are the most common trees; some forests contain alders, poplars, and beeches. The most common Japanese fruits are peaches, pears, and oranges.

The Japanese practice a unique kind of landscape gardening. Japanese gardens attempt to reproduce in miniature a stylization of natural landscapes. The Japanese also cultivate dwarf trees, such as the cherry and plum, which, through skillful pruning, are kept as low as 30 cm (12 in). The potted flora that are dwarfed by special methods of culture are called bonsai.