Devi Damanotsav is observed during Vasant Navratri in Chaitra Month. In 2017, Devi Damanotsavam date is April 5.
It marks the end of Navratri Durga Puja as it is observed on Durga Navami, 9th or final day of Navratri (Shukla Paksha Navami in Chaitra maas).
Goddess Durga is worshipped with Damana or Dhavanam leaves (botanical name: Artemisia pallens).
This day is also observed as Durga Navami, Maha Navami & Sri Ram Navami.