Ok, so in this new scenario, there are still people? Still grass? Still flowers in the grass?
The people still mow the grass during the warmer months? Presumably to make things look nice still (the virtue)? And this keeps the flowers from growing? Or at least blooming? Because they are taller than the grass?
Global warming (the vice) has caused shorter winters? And at some point, approaching winter, they stop mowing (practical consideration)? But not just when the grass stops growing? Before the grass stops growing? Do they stop mowing at the same time of year as before? Which leaves a gap for the flowers to grow?
Yes to all, and good enough for the SPOILER:
The bureaucracy dictates that mowing of parks and other public grass should end in the beginning of october. If winters keep being as mild as this one, and bureaucracy as tenuously connected to reality as always, this will give bluebells a chance to flower on public grass in the autumn, while those in wild grass flower during summer. If the october bluebells only get to pollinate other late bloomers, we may get two separate species.
I'm no botanist and have no idea if this is likely to happen, but last year was the first time I saw bluebells in october.