Khordad Sal is the birthday of Zoroaster (Zarathustra), the prophet and founder of Zoroastrianism. The holiday usually falls sometime after Nowruz and is often called “Greater Nowruz.” Celebrants pray, hang fresh flowers in their home, and make vibrant drawings (rangoli) on the floor.
Sourced from https://www.vanderbilt.edu/isss/khordad-sal