The green teej of Shravana, kept by married women through the monsoon.
Hariyali Teej is Shravana Shukla Tritiya — the Tritiya of the shukla fortnight of Shravana. It is kept at sunrise, so the date is the day that tithi is running the tithi that is running when the sun comes up.
Computed from the Moon’s elongation with the Swiss Ephemeris, sidereal, Lahiri ayanamsa. A tithi begins and ends at a real minute rather than at midnight, which is why the moment above decides the day — and why the same tithi read at a different hour can name a different date.
Cast a free kundli, or ask any of 24 astrologers what this year actually holds for you. Billed by the minute, and only while somebody is answering.