Sigh...."summer blowing away"......as it always does. Poignant, kiddo!
I'm thinking about the concept of just surrendering to the changes - even seeing beauty in the death of things. I've caught "wabi sabi"!!! Just saying...still, loss is loss.
the poem pivots, both formally and philosophically, on "shaping," doesn't it? the recognition that time is not simply a flowing away, but a contour, a work of shape ... and of course that the garden one has shaped will ultimately be re-shaped by natural process ...very good :-)).
Thanks for your thoughtful comment. If I had titled it, I would have named it Cycle, or even Rebirth but, with haiku, titles are a too clunky and you are right, the focus is on the shaping, not where it is going.