Devotees keep a partial or day long fast on this day. They and eat only fruits, vegetables and root plants throughout the day. Peanuts, potatoes and sabudana khichdi are prepared especially to mark this day's fasting. The day's fasting is broken only after the main pooja is done.
The main puja of the day is done in the evening, after the moon is visible. The idol of Lord Ganesha is worshiped with Durva grass, fresh flowers and incense sticks. Lamps are lit, and devotees read the "vrat katha" specific to the month in which the Chaturthi is. The rituals for this day end with the sighting of the moon.
Special sweets or naivedya, including modaks, are
offered to the deity during the pooja. After the katha and aarti, these sweets
are distributed as prasad. Apart from worshiping Lord Ganesha, the moon is also
worshiped on Sankashti Chaturthi. Water, chandan or sandalwood paste, rice and
flowers are offered in the direction of the moon. Finally reciting the Vedic
hymns or mantras devoted to Lord Ganesha garners blessings on this day.
Devotees chant the Ganesha Ashtothra, Sankashtnashana sthothra and Vakrathunda
Mahakaya especially on Sankashti Chaturthi.