We live alongside a natural air conditioner. In summer, the breezes off Maine's Western Bay keep us cool even on days when inland temperatures hit the high 80s. Those same breezes now serve as coastal heaters, fending off the first, flower-wilting frost.
For a while.
By the time we return from our western bird adventure, the resplendent dahlias we first put in starter pots last April (http://naturalistsnote.wordpress.com/2010/04/13/planting-and-painting-dahlias-and-other-april-adventures/) will be gone. We'll have to dig up the tubers and store them in the basement for the winter. I've been reading a little about the genetic complexity of dahlias—they have eight sets of chromosomes instead of two, as most flowers do, which helps explain why there are so many varieties that look so different from each other.
Our garden has dahlias that look as alien to each other as a dachshund and a St. Bernard—which of course are also related (and in fact get along with each other better than many humans do). Dahlias were first cultivated by the Aztecs, then discovered by Spanish explorers, who brought them back home. At first the tubers were thought of primarily as food (they are edible), but the flowers turned out be considerably more enjoyable. Dahlias are still Mexico's national flower.
A beneficial quality of dahlias and other flowers that blossom well into fall is that they provide nectar for pollinators after other flowers have signed off for the year. If you live in frost country, enjoy the days that are left before we say goodbye for 2010 to the bees, the butterflies and the blossoms.