Chaucer’s General Prologue to the Canterbury Tales has a famous beginning; it states the season:
Whan that Aprille with his shoures soote,
The droghte of March hath perced to the roote,
And bathed every veyne in swich licour,
Of which vertu engendred is the flour
[When April with its sweet-smelling showers
Has pierced the drought of March to the root,
And bathed every vein (of the plants) in such liquid
By which power the flower is created]
It hits all the tropes of spring: growth, fecundity, moisture. It explains that this is the season of pilgrimage: