By Barbara Fair
I have received a number of questions regarding Callery pear, cherry and other typically spring-flowering trees and shrubs blooming and leafing out again this fall.
It is likely a stress response related to Hurricane Florence.
Late winter and spring flowering trees and shrubs begin to develop new flower buds for the following year after they finish flowering, and during the summer when they are in full leaf. There is a complex relationship between flowering response, plant hormones and plant chemistry. Day length and temperature play an important role when plants flower in general. When seasons change, plants respond by altering their internal chemistry and hormone levels.
This is normal, but when storms come through and change the conditions directly around the plant, it can trigger an unusual response, such as plants blooming out of season. The storm can lead to stress, which leads to a change in the plant’s hormone levels and chemistry. Thus, plants bloom at strange times and may even produce leaves where others were lost.
It is rather complicated and no one factor seems to explain it. As with most issues with plants, it is usually a suite of factors that play into a plant’s response to stress.
It is unlikely these trees will bloom again in the spring. They may have a few blossoms left over after this flush, but blooming will be much diminished, if at all. There should be no problem when it comes to developing new leaf buds and leafing out in the spring/early summer, but they are using some of those performed leaf buds as well now, so you might see some regrowth, late leaf flushing or reduced leaves at the beginning of the season. If the trees are otherwise healthy, there should be no long-term effect on the production of new leaves. Callery pear is one of the toughest plants in the landscape and should be fine despite the hurricane’s effects.
Dr. Barbara Fair is an Extension Landscape Specialist & Associate Professor at North Carolina State University.