Significance
Dev Uthani Ekadashi (Prabodhini Ekadashi or Devuthani) falls on the eleventh day of Kartika Shukla Paksha and marks the awakening of Lord Vishnu from his four-month cosmic sleep (Yoga Nidra) that began on Devshayani Ekadashi in Ashadha. During these four months (Chaturmas), auspicious ceremonies like weddings were forbidden. With Vishnu's awakening, the cosmic order resumes and the wedding season begins. Vishnu is worshipped with Tulsi on this day -- the sacred marriage of Vishnu and Tulsi (Tulsi Vivah) is also performed.
Preparation
Rituals & Vidhi
Vishnu Awakening Puja
Perform puja to Lord Vishnu at dawn, chanting "Uttishtha Govinda" (Rise, O Govinda). Offer Tulsi, yellow flowers, and panchamrit.
Mantra: Uttishtha Uttishtha Govinda Tyaja Nidram Jagathpathe. Tvam Suthey Jagath Suptham Uttishthey Jaagatham Tvayaa.
Tulsi Vivah
Perform the sacred marriage of Vishnu (represented by a Shaligram stone or idol) to Tulsi Devi. Dress the Tulsi plant as a bride with a red dupatta, bangles, and sindoor. Perform all wedding rituals (Saptapadi).
Amla Worship
Worship the Amla (Indian gooseberry) tree today -- Vishnu is said to reside in it. Sit under the tree and take a meal there if possible.
Dwadashi Parana
Break the Ekadashi fast on Dwadashi morning. The Tulsi Vivah effectively opens the auspicious season -- visit family to announce upcoming celebrations.
Fasting
Observe the standard Ekadashi fast -- no grains, lentils, onion, or garlic. Fruits, milk, and sendha namak are permitted. The fast culminates with the Vishnu awakening puja and is broken on Dwadashi.
Family Guidance
The Tulsi Vivah is a beautiful family ceremony for children to witness and participate in. Dress up the Tulsi plant together, perform the ceremony with full ritual detail, and teach children that the Tulsi plant is itself a form of the Goddess.