Can't remember if it was year before last or the year before that but we had a very wet summer here in S.W. Ontario . For the first time in about 12 years of growing daylilies I had H. Flava rebloom. Now that was a real shock to me as it usually blooms the end of May here and then that's it for the season , but not that particular year . So was it because it was a wet summer or cooler grey sky summer ? I have no clue . I do recall this distinctly because it was such a shocker . I even dragged my DH off the porch to see what to me was a real oddity.