Use the adjective Frostian to describe a piece of writing that resembles the style or themes of the poet Robert Frost. If your cab driver starts regretting "the road not taken," then call him Frostian.
Your poem might be called Frostian if it's traditional in form — especially if it rhymes and falls in regular meters, and if its subject is New England. It's not truly Frostian, however, unless there is some modern theme or idea that's communicated in a striking, direct way. Robert Frost's work managed to straddle the nineteenth and twentieth centuries in style and subject, bringing the old and new together in a way no other American poet did.