Amalaki Ekadasi, also written as Amlaki or Aamalaki Ekadashi, occurs during the waxing phase of the moon in February – March. In 2015, the date of Amalaki Ekadasi is March 1. Ekadasi fasting is dedicated to Lord Vishnu and is observed on the 11th day of waning and waxing phase of moon in a traditional Hindu calendar. The greatness of Amalaki Ekadashi was narrated by Sage Valmiki and is mentioned in the Brahmanda Purana.

It is believed that by observing Amalaki Ekadasi, a devotee attains Moksha and washes away all the sins committed. Special pujas and offerings are made of Amalaki Tree and Lord Parashurama on the day.

There are numerous folk tales and stories in Puranas that extols the greatness of Amalaki Ekadasi.

Most devotees fast on the day and keep vigil in the night. Those people observing partial fasting abstain from food made of rice.

As this Ekadasi falls before Holi festival the day also forms part of Holi celebrations for some Hindu communities. Thus it is also known as Aanwla and Kunj Ekadasi.

Amalaki Ekadashi is also observed as Papanasini Ekadasi in some regions.

source – http://www.hindu-blog.com/2009/02/amalaki-ekadasi.html