Ambuvachi is a rite observed in most of North and central India, but most elaborately in Bengal. During four days in the Hindu month of Ashadha (June–July), just before the rainy season is to begin, the earth goddess is said to menstruate in order to prepare herself for fertility. During this period all plowing, sowing, and other farm-work are suspended. Widows may be required to observe special taboos during Ambuvachi, as they are not involved in procreation.
Further reading: Abbe J. A. Dubois, Hindu Manners, Customs and Ceremonies. Translated from the French by Henry K. Beauchamp (Oxford: Clarendon Press, 1959); Swami Harshananda, Hindu Festivals and Sacred Days (Bangalore: Ramakrishna Math, 1994).
Encyclopedia of Hinduism. A. Jones and James D. Ryan. 2007.