Astronomical and solar reckoning
In some cultures in the Northern Hemisphere (e.g. Germany), the astronomical vernal equinox (varying between 19 and 21 March) is taken to mark the first day of spring, and the summer solstice (around 21 June) is taken as the first day of summer. In Persian culture the first day of spring is the first day of the first month (called Farvardin) which begins on 20 or 21 March. In other traditions, the equinox is taken as mid-spring.
In the traditional Chinese calendar, the "spring" season (春) consists of the days between Lichun(February 3–5), taking Chunfen (March 20th-22nd) as its midpoint, then ending at Lixia (May 5–7). Similarly, according to the Celtic tradition, which is based solely on daylight and the strength of the noon sun, spring begins in early February (near Imbolc or Candlemas) and continues until early May (Beltane).