I cut my blooms back when they turn brown and yucky and sometimes when they are still nice for arrangements and mine just started getting a few new blooms. Since they bloom on new growth i say go for it. Maybe you'll get more, and even if not the plant can save it's energy for roots and growth for next year. And if your end of season blooms look anything like mine they aren't worth leaving on anyway. Not sure if it's all the heat and humidity but mine turned a rusty brown and shriveled. Not pretty.