Talking plants

Jillian Patrie | University of Minnesota Yard & Garden Extension

What makes a plant go to sleep in the fall and how does it know when to wake up? Plant dormancy is affected by day length and temperature; August, in the FM area is when we start to notice the angle of the sun change and the cooler nights begin.
Acclimation is the term that describes the physical and physiological process that protects plants through the winter months. It is also what allows us to endure the cold and endlessly windy Red River Valley winters. Temperatures have some influence over dormancy, but the biggest player is the long winter nights that we know all too well. The same reasons that make humans tired in the winter affect plants too! Plant hormones are influenced by photoperiodism (daylength), and plants use this que to help them stay asleep for the right amount of time each winter.
The length of dormancy varies by species and duration of cold temperatures, and it is important for plants not to wake up too soon to avoid cold damage. In general plants will break dormancy, when buds (where new leaves push out) experience 24-50 degrees F for 4-8 weeks. With that said, what happens when warm winters like this current one occur?
The answer depends on the future temperature trends and what plants have already been nudged out of dormancy. Some plants like spring bulbs (tulips, daffodils, crocus) are more adapted to fluctuating spring temperatures and can tolerate being nipped by a cold snap and some plants native to northern regions are not easily tricked out of dormancy. In general, hardy plants that are exposed to cold temperatures while leaves are emerging may have some damage to leaves & buds, but the plant will survive. Fruit trees that experience late spring frost after flower buds or flowers have emerged may have lower fruit yields for that growing season. Time will tell, as spring approaches how our hardy plants fared after this warm winter weather.
A few things to consider as this warm winter continues. Tree & shrub trimming: If your tree or shrub is showing signs of waking up; like swollen buds or buds that have already opened, hold off on winter trimming for this season.
***Apple trees: Apple trees can be pruned closer to budswell or even at bloom. If fire blight has been an issue with your apple trees it is best to prune them while dormant to avoid spreading the disease. Lawns are still sleeping; soil temperatures need to be above 45 F for lawns to start waking up and that occurs when air temperatures are consistently 50-60 F.
Avoid cleaning up your gardens and other spaces in your yard. Insects are still sleeping and many of our pollinator friends overwinter in leaf piles, spent plant stalks and other plant debris.

The full article: How will this warm winter affect my plants? Can be found on the UMN Yard & Garden Extension website, extension.umn.edu. If you have any questions regarding this article please contact the University of Minnesota Extension Office, Clay County at 701-299-7338 or by email at patri350@umn.edu.