Which poetic device is used here "love is a garden of flowers - some sweet smelling, some foul.

metaphor

A metaphor is a comparison between two things without using like or as. In this sentence the speaker is comparing love to a garden of flowers. The purpose is to show how sometimes love can be sweet and sometimes love can be foul. The speaker does not use the word like or as to make the comparison. Other examples of metaphors are My pillow is a cloud. The road race was run by cheetahs.

often a noun phrase is just a noun or a pronoun:

people like to have money.

i am tired.

it is getting late.