If you live in a temperate region, chances are your trees and shrubs are all still bare. Perennial plants go dormant throughout the winter, which means they cease to grow. Actually, perennials go through two forms of dormancy, and they need to break both forms before any of us can have spring again.
Starting in the fall, frosty weather and dwindling daylight cause plants to enter endo-dormancy. Chemical signals from the plant block growth at buds, which will not grow even if the conditions somehow change to become favorable. Endo-dormancy must be broken by a prolonged period of cold. Plants track the amount of time they spend in temperatures just above freezing. When the proper amount of time has been reached, the buds become competent for growth again. Different plants require varying amount of time in the cold. If the period of chilling is disrupted, it resets the entire process and the buds remain dormant.
If the plants are sufficiently chilled they enter the second phase of dormancy, eco-dormancy. While the buds are capable of growth, the dark, chilly winter weather keeps them in a slumber. The plants continue to track the hours of daylight, temperature and moisture and when all three are just about right… Spring. Turns out it takes a lot of hard work to wake up a plant. I think that’s something the majority of humans can relate to.
Brian Rutter, PhD, is the cofounder of Thing in a Pot Productions and a postdoctoral researcher in plant biology at Indiana University. Subscribe to our newsletter to receive our “Things About Things – Odd Facts About Plants” and video production tips in your inbox every month!