The birthday of the historical Buddha is celebrated on different dates by various schools of Buddhism. In most of Asia, it is observed on the first full moon date of the fourth month in the Chinese lunar calendar (typically May). But in other parts of Asia, the day falls earlier or later by a month or more.

Theravada Buddhists combine observance of Buddha's birth, enlightenment, and death into one holiday, called Vesak or Visakha Puja. Tibetan Buddhists also combine observance of these three events into one holiday, Saga Dawa Duchen, which usually falls in June.

Most Mahayana Buddhists, however, separate observance of Buddha's birth, death, and enlightenment into three separate holidays held at different times of the year. In Mahayana countries, Buddha's birthday usually falls on the same day as Vesak. But in some countries, such as Korea, it is a week-long observance that begins a week ahead of Vesak. In Japan, which adopted the Gregorian calendar in the 19th century, Buddha's Birthday always falls on April 8.

Whatever the date, Buddha's Birthday is a time for hanging lanterns and enjoying communal meals. Joyous parades of musicians, dancers, floats, and dragons are common throughout Asia.

In Japan, Buddha’s birthday—Hana Matsuri, or “Flower Festival”—sees those who celebrate going to temples with offerings of fresh flowers and food.

Washing the Baby Buddha

One ritual found throughout Asia and in most schools of Buddhism is that of washing the baby Buddha.

According to Buddhist legend, when the Buddha was born, he stood straight, took seven steps, and declared "I alone am the World-Honored One." And he pointed up with one hand and down with the other, to indicate he would unite heaven and earth. The seven steps the Buddha took are thought to represent seven directions—north, south, east, west, up, down, and here. Mahayana Buddhists interpret "I alone am the World-Honored One" to mean 'I represent all sentient beings throughout space and time'—everyone, in other words.

The ritual of "washing the baby Buddha" commemorates this moment. A small standing figure of the baby Buddha, with the right hand pointing up and the left hand pointing down, is placed on an elevated stand within a basin on an altar. People approach the altar reverently, fill a ladle with water or tea, and pour it over the figure to "wash" the baby.