Nimba Saptami is observed on Shukla Paksha Saptami in Margashirsha Month. In 2016, Nimba Saptami date is December 6.
Nimba Saptami is dedicated to Neem Tree (botanical name: Azadirachta indica). Neem Tree is worshipped on this day mainly in North Indian states.
Nimba Saptami is also dedicated to Surya Bhagavan. It is also observed as Nanda Saptami, Vishnu Saptami, Mitra Saptami, Bhadraa Saptami, etc..