plant life vs half-hardy

plant life is a noun but half-hardy is not a noun.

Word	Noun	Adjective	Verb	Adverb
plant life	Yes	No	No	No
half-hardy	No	Yes	No	No

plant life (noun)	half-hardy (noun)
(botany) a living organism lacking the power of locomotion

plant life (adjective)	half-hardy (adjective)
	(of plants) requiring protection from frost