The Autumnal Equinox is the best time for wheat - sowing.
秋分种麦最相宜.
📖 牛津释义
equinox
n
either of the two times in the year (around 21 March and 22 September) when the sun crosses the equator and day and night are of equal length 春分; 秋分
spring/vernal equinox 春分
autumnal equinox 秋分. Cf 参看 solstice.