|Thanks for your review, Holden Caulfield!
"Whose brilliant red will surely stain?" I don't think the question mark should be there.
"The sky an empty canvass, Broken only by a plane..." I would suggest replacing broken with a word like marked or marred. The plane isn't necessarily breaking the canvass, is it? With your metaphor of the sky is an empty canvass, I think it would make more sense for something to mark or mar the canvass rather than break it.
Favorite lines: "The sky reflects the soul, the clouds our passing thoughts" "Whose brilliant red will surely stain the dewy grass"
In this poem, there seems to be a sense of disappointment in the turning of summer to autumn. Is this correct?
Great imagery, personification, and metaphor.
Overall, a good poem that conveys feelings about the change of seasons in a thoughtful, pensive way.