In the South Indian lunar calendar it falls on the fourth day of the bright moon of Bhadrapada — usually late August or September. Hindus everywhere bring Ganesha into their homes on this day, honour him for ten days, and finally release the murti into flowing water. The ritual is called Visarjana, and it means: the divine doesn't come to stay, it comes to be given away.
In Berlin we concentrate the festival into a single day: Abhishekam in the morning (anointment of the murti with milk, yoghurt, honey and ghee), bhajan and Vedic recitation through the day, the great Aarti in the evening, and modaka — Ganesha's favourite sweet, filled with coconut and jaggery — for everyone who comes. Afterwards Mahaprasadam for the whole community.