Blooming in Winter
Rosie Lerner, Extension Consumer Horticulture Specialist, Department of Horticulture and Landscape Architecture, Purdue University
Many gardeners have observed plants blooming out of sync this month. At the Purdue Horticulture Gardens, West Lafayette, Indiana the following plants were notably flowering on December 19, 2012. Our gardens are in a unique mild microclimate thanks to underground steam utilities, but other gardeners have noted similar action in their flower beds.
Bearded iris, Centaura montana, flowering cabbage, foxglove, Jupiter's beard, 'Knockout' roses, shasta daisy, snapdragon, sweet alyssum, and sweet William.
Some are annuals, some biennials, some are biennials more typically grown as annuals in our climate and some are perennials. All would typically be dormant and not in flower in December. This fall, we received enough cold weather to satisfy the chilling requirements needed to initiate flowering (known as vernalization), yet not cold enough to kill the stems or, in some cases, new stems have grown. And in some cases, they just never really shut down.
Click image to enlarge
Knock Out Rose