Cherry blossom in Japan

The Japan Meteorological Agency observes designated sample trees (hyōhon-boku) in cities across the country. The blossom is declared open (kaika) when five or six flowers have opened on the sample tree, and in full bloom (mankai) when about eighty per cent of the buds are open. Tokyo's sample tree stands in the grounds of Yasukuni Shrine.

Most observations use the somei-yoshino, a grafted cultivar from the late Edo period that now dominates Japan's parks. Because the trees are clones, they flower almost simultaneously in a given place, which produces the spectacular mass bloom. In Okinawa and in northern and eastern Hokkaido, where somei-yoshino does not grow well, other species are observed.

The dates below describe a typical year; the actual timing shifts by a week or more depending on the winter and early spring temperatures. Warm springs bring the blossom forward, and in recent decades average opening dates in many cities have become earlier.

Within one region, altitude matters as much as latitude: mountain towns and higher parks bloom later than the nearby coast, which extends the season for anyone willing to travel inland.

Many of the most famous spots combine blossom with a castle, temple or river. The busiest are crowded from dawn during full bloom, and some are illuminated in the evening (yozakura, 'night cherry').

Somei-yoshino is only one of hundreds of cultivars. Early-flowering kawazu-zakura, with deep pink flowers, blooms in February on the Izu Peninsula in Shizuoka. Weeping cherries (shidarezakura) often open a few days before somei-yoshino, while the double-flowered yaezakura follow one to two weeks later, prolonging the season in cities such as Kyoto and Nara.

Some individual trees are famous in their own right, such as the ancient Miharu Takizakura in Fukushima, a weeping cherry more than a thousand years old according to local tradition.

Forecasts from the Japan Meteorological Agency and private weather services are published from late winter and updated frequently; long-range predictions are only a guide. Because the blossom lasts about a week in each place, a trip that moves north or into the mountains, for example from Kyoto to Tohoku, has a better chance of catching full bloom than a fixed stay in one city.

The season coincides with a peak in domestic travel, so rooms in Kyoto and near famous spots should be booked early. Hanami etiquette asks visitors not to shake or break branches, to take rubbish home and to follow local rules on sheets, alcohol and barbecues.