After reading the forum challenge, I can definitely appreciate what you've done here. I myself am tempted to try my hand at it and accept the challenge.
In the end this simple bit of poetry possesses so much imagery for me. I see a gorgeous portrait throughout changing with nature and magic. You have a lovely way with words - I especially adore the use of "yearlings" and "delphiniums".
The last stanza is simply enchanting.
"Lady youth has seldom met temptation, now woes struggle, each horse enchants, she exalts."
"she exalts" in itself leaves me pondering. I love poetry with the power to inspire. This is fantastic poetry. Wonderful work.