Autumn is the time of transformation between the growth of summer and the dormancy of winter. Things are winding down, and once the harvest is complete, there is nothing left to do but wait until the next season. Much of the transformation in the poem occurs between stanzas. For example, in the first stanza fruits and gourds are swelling outward before they will be picked for food. By the second stanza, the harvest is already complete, or mostly complete, and the ripe apples have been turned into rich, delicious cider. The third stanza focuses only on one transformative event, the setting of the sun.
The scenery of "To Autumn" changes, but there is no development of themes or ideas.
The end of "To Autumn" is much more ambivalent about the season than the beginning.