Old English, present-participle adjective from grow (v.). Growing season is attested from 1729; growing pains by 1752.
growing (n.)
late 14c., "a gradual increase, action of causing to increase," verbal noun from grow (v.). Meaning "that which has grown, a crop" is from 1540s. Dialectal growsome "tending to make things grow" is from 1570s.
the growing season for corn
good growing weather
grove
grovel
grow
grow up
grower
growing
growl
growler
grown
grown-up
growse