'long-blooming' originates from Modern English, specifically a compound of the adjective 'long' and the present participle 'blooming' (from the verb 'bloom'), where 'long' meant 'of great duration' and 'bloom' meant 'to produce flowers'.

'long' changed from Old English 'lang' (meaning 'long') and 'bloom' derives from Old English 'blōma' (noun) / 'blōwan' (verb); the compound 'long-blooming' is a straightforward Modern English formation combining these elements to describe extended flowering.

Initially the elements meant 'great duration' and 'to produce flowers'; over time the compound 'long-blooming' came to be used in Modern English specifically to describe plants that have an extended period of flowering.