Shaka Vrata is observed mainly in South India by certain Hindu communities and is dedicated to Srihari Vishnu. Shaka Vrata is a month long ritual and begins on the 11th day of the Shukla Paksha or waxing phase of moon in Ashada Month. Shaka Vrata in 2011 begins on July 11. Shaka Vrata ending date is August 9.
The Vrata begins on the Shukla Paksha Ekadasi in Shravan month. This is the famous Devshayani Ekadasi and the Chatur Masa Vrata also begins on the day.
The Vrata ends on the Shukla Paksha Ekadasi in Ashada month. This is the Putrada Ekadasi.
The popular belief is that Srihari Vishnu enters into a deep slumber on Devshayani Ekadasi – the night time of Devas.
There is no fasting associated with the Shaka Vrata. People follow a strict vegetarian diet.