The Equinox March Flag shows the Earth in balance between night and day. The day side is light blue with a full yellow Sun, while the night side is black with a crescent moon and seven stars. In the center is the Earth in a blue ringed ocean. The modified Yin and Yang symbol represent the Spring and Summer. As Spring is starting in the North, Autumn is starting in the South. The Spring colours are green with an eye of yellow, pink, and red, while the Fall colours are brown with an eye of yellow, orange, and red.
The Equinox is when daytime and nighttime are in nearly perfect balance, which only happens two days out of the year.
September Equinox Flag
For the September Equinox all one has to do is flip the flag. Also note that Summer ends in late September! Culturally in America it ends after Labor Day, but mid-September is still Summer. Likewise Summer begins in the end of June, but culturally it starts the day after Labor Day, in Late May in the USA.