What is the connection between Devuthani Ekadashi and Tulsi Vivah?

According to the Skanda Purana (Vaishnavakhanda, Chapter 33), Lord Vishnu sleeps during the four rainy months (Chaturmasya) and awakens on Prabodhini Ekadashi (also called Devuthani Ekadashi) — the eleventh day in the bright half of Kartik. The text specifically instructs that as part of the Tulsi Vivah procedure, the devotee must first “awaken the Lord by prayers” before performing the marriage. This is why Tulsi Vivah is celebrated the day after Devuthani Ekadashi on Kartik Shukla Dwadashi — it celebrates Vishnu’s return to active governance of the universe, and his wedding to his beloved Tulsi (Vrinda) marks the end of the sacred Chaturmasya period and the official start of the Hindu wedding season.