The dates below are days that are not good days to put up new prayer flags.
February (2021):
March: 17, 29
April: 9, 16, 28
May: 9, 12, 14, 26
June: 20
July: 1, 16, 27
August: 12, 23,
September: 4, 7, 18
October: 1, 15, 27
November: 14, 26,
December: 10, 23
January (2022): 6, 18, 30
February: 1, 14
These days in the year 2021 are not the best days to raise prayer flags, according to the Tibetan calendar.