Bohag Bihu is observed from the last day in the last month of Assamese calendar Chata (called Sankranti, transit or passage from one zodiacal sign to another). Earlier Bohag Bihu was celebrated for seven days together and each day had a different name like Goru Bihu (for cows), Manuh Bihu (for mankind), Tator Bihu (for loom), Gossain Bihu. (for Gods), Nangalor Bihu (for plough), Bihu for domestic animals and Chera Bihu (concluding day of the Bihu). Bohag Bihu is the season of unfettered greenery with early monsoon, and with Nature clad in beautiful colours. Such variety is not to be found elsewhere. On the first day of this Bihu, which is meant for the cows, in the early hours of the morning cows are taken out for washing in .the nearest ponds and ‘Beels’. With the help of a small three pronged shaped Bamboo implement, brinjals and water gourd are cut into pieces and hurled at the cows. Other vegetables like bitter gourd, turmeric and Thekera (the gamboze fruit) are also used. These implements are interchanged with others to ward off the evil. Later in the evening when the cows return ho-me they are tied to new Pogha (rope for tying cow) and the shed is filled with smoke to prevent any evil. Cows are indispensable for cultivation and thus such treatment on the special day.

Another important ritual of this day is that ladies and girls apply henna and mehendi on their hands and feet. Mehendi (locally known as Jetuka) is a way of bringing colour to life, apart from its medicinal properties. Manuh Bihu follows Goru Bihu when people visit relatives and exchange Garnochas (a kind of towel woven in cotton). Bihuwan or this Gamocha is a symbol of dignity in Assamese society. Jalpaan, a special food item, is an important part of Bihu.