Tulsi Vivaha celebrates the divine Tulsi plant; a favorite of Vishnu. For the complete story listen to the Tulsi Vivaha podcast or read the story in the show notes on puja.net. For the pujas in this celebration, they replace a traditional murti with the tulsi plant as representative of the simple devotion of Lakshmi.
A full puja is performed and then the traditional vedic marriage ceremony is performed (called Kalyana Utshavam).
By the end the puja areas is full of flowers!