Why the days are inauspicious
Tradition holds that in these eight days Hiranyakashipu tormented his son Prahlada, trying again and again to kill him for his devotion to Vishnu, until on the full Moon Holika sat with him in the fire. Another story says that Kama, the god of love, was burned by Shiva on the Ashtami, and the world mourned him for eight days. Astrologers add that the grahas are in a fierce state through these days, one on each day.
What is done
On the first day a pole or a branch is set up at the place where the Holi bonfire will be lit, and wood and cow-dung cakes are added to it day by day. Weddings, housewarmings, the first haircut of a child, the thread ceremony, buying property or vehicles and starting a business are put off. Devotion, charity and the worship of Narasimha and Hanuman are encouraged instead. The custom is kept mostly in Punjab, Haryana, Rajasthan, Uttar Pradesh and Madhya Pradesh.
When the bonfire burns on the full Moon, Holashtak ends, and auspicious work can begin again after Holi.
Holashtak and astrology
Astrologers explain that in these eight days the grahas are in a fierce or unsteady state: the Moon on the Ashtami, the Sun on the Navami, Saturn on the Dashami, Venus on the Ekadashi, Jupiter on the Dwadashi, Mercury on the Trayodashi, Mars on the Chaturdashi and Rahu on the Purnima. Decisions taken now are thought likely to be hasty, so new ventures wait until after Holi.