For the past few weeks at GH in Sebastopol, we have been anxiously anticipating the opening of the swelling blossoms on our beautiful ornamental plum trees. The presence of flowers is surprising to see since winter has barely begun, and fall is still lingering in the background (apparent by looking at our Liquid Amber trees at the peak of their display of brilliant leaf color). While it is unusual to see trees flower so early, this is not necessarily an indicator of global warming, but instead the result our ability to breed trees that have very little dormancy requirements. As you know, some plants flower due to photoperiod (the amount of uninterrupted darkness it receives at night), while others simply flower after a certain amount of time has passed. Many trees go dormant in the fall/winter and drop their leaves, and are only able to overcome dormancy based on how many chilling hours they receive. In other words, they are ready to flower once they have been exposed to a certain temperature (typically between 45ºF and 32ºF) for a specific amount of time. Breeders have been able to reduce or extend required chilling times by selectively crossing varieties that flower under specific numbers of chilling hours; development of varieties with altered chilling requirements allows for crops to be cultivated in regions where they would otherwise never grow.
Before the winter blues get you down, just take a moment to enjoy what nature( and thousands of years of human driven breeding) have given you. Spring will be here before you know it.