'prolonged-blooming' is a compound formed from 'prolonged' and 'blooming'. 'prolonged' originates from Latin, specifically the word 'prolongare', where 'pro-' meant 'forward/toward' and 'longus' meant 'long'. 'bloom' originates from Old English, specifically the word 'blōma', where it meant 'flower'.

'prolongare' (Latin) passed into Old French as 'prolonger' and into Middle English as forms such as 'prolongen'/'prolong', eventually producing the Modern English past participle 'prolonged'. 'blōma' (Old English) became Middle English 'blome'/'bloom' and developed into Modern English 'bloom', with 'blooming' as the present participle; the compound 'prolonged-blooming' is a modern descriptive compound used in horticulture and plant descriptions.

Initially, 'prolongare' meant 'to make long' and 'blōma' meant 'flower'. Over time the elements retained their senses and the compound came to mean 'having an extended flowering period' in modern usage.