Mahalaya
A week before Navratri begins; the idols of Goddess Durga are painted and made ready except for the eyes. On the occasion of Mahalaya, the Goddess is invited on earth with rituals and so on this day, the eyes are drawn on the idols in an auspicious ritual called Chokku Daan. It is believed the Goddess descends to earth at the time of drawing the eyes on the idols.

Saptami
This is the ritual of invoking the presence of the Goddess in the idol. This takes place on the seventh day, when early in the morning; a small banana plant called Kola Bou is taken to the river to be bathed and dressed in a red-bordered sari and carried back in a procession to be placed near the idol of the Goddess. This is then followed by ritualistic prayers and puja, that will take place for all the remaining days of the festival.

Ashtami
Legend has it, before Mahishasura’s annihilation, his two generals, Chondo and Munda, were slayed by Devi Durga, transformed as Devi Chamunda in the transition period of Ashtami and Navami, known as Sondhikhon. Sandhi Puja is celebrated to worship the Chamunda form of Goddess Durga. A special prayer is offered to the deity during the symbolic time of dusk in the last 24 minutes of Ashtami and first 24 minutes of Navami. This 48 minute period of Sondhi is considered the most pious and powerful period of the festival.
It is considered as the highest form of the worship. During this ritual 108 lamps are lit and 108 lotus flowers are offered. Many rituals and traditions are associated with Sondhi Khan (literally meaning minute).
In ancient times, it was a ritual to sacrifice animals in order to complete the Puja but now, only a symbolic sacrifice is performed with vegetables like banana, cucumber or pumpkin.

Dashami
On the tenth day Durga returns to her husband the ascetic Shiva. After the feasting on the tenth day the food is plain vegetables and fruits to accustom her to her husbands Spartan lifestyle. The women feed her sweets and smear sindoor to bid her goodbye till next year. The sindoor represents marriage and fertility

 

The nine plants of Nabapatrika represent nine Gods / Goddesses. These are the Banana plant (Goddess Brahmani), Colocasia plant (Goddess Kalika), Turmeric plant (Goddess Durga), Jayanti plant (Goddess Kartiki), Bel leaves (Lord Shiva) Pomegranate leaves (Goddess Raktadantika), Asoka leaves (Goddess Shokarahita), Arum plant (Goddess Chamunda), Rice paddy (Goddess Lakshmi)

(Source: Free Press Journal)