The speaker of the poem has a direct hotline to speak with the seasons. He also has an omniscient viewpoint on this woman named "autumn" who likes to relax in various autumn-y places. He manages to track her down from place to place, which sounds like no small feat. He has a keen imagination and takes notice of things the rest of us might miss, like the "bars" in the clouds or the moss on the cottage-trees. His perspective has the effect of a magnifying glass.
He assumes that everyone knows who this lady autumn is, and that all of us readers have seen her sitting in granary. What he really wants to say is, "I've seen autumn on the granary floor." He's also slightly aggressive when it comes to springtime. At the beginning of the third stanza, he puts his hand to his ear and is like, "Where are you at now, Spring?" He looks around and shouts, "I can't hear your songs, Spring!" He's obviously protective of autumn and, on the plus side, he would make a loyal friend. He's the kind of person who always wants to remind you of your good qualities when you're feeling a little inadequate. "But what about the time you did this cool thing?" Oh, yeah, thanks!