We often say that plants “go dormant” in the fall and winter, but what does that mean? As we see our environment change with the season, the plants around us reveal unique characteristics that can be useful for plant identification.
Today, we’re taking a closer look at what really happens to plants in the fall!
Going Dormant
You might have heard the phrase that plants “go dormant” in the winter, so what does it mean?
It’s kind of like hibernation, but the plant version. Essentially, it’s a period of reduced activity during which the plant’s growth either slows or stops. In this period, many trees and shrubs shed their leaves to reduce water loss and protect themselves against freezing temperatures. Perennial herbaceous plants completely retreat underground, keeping their energy stored in their roots.
Even though these plants may look dead, they are very much alive!
What does the term “die back” mean?
Dieback is closely related to plant dormancy. In the context of fall, when a plant is said to “die back”, it refers to the loss of leaves, stems, and other above-ground growth. These plants are withdrawing all their above-ground growth and returning to their roots.
Herbaceous vs Woody Plants
Herbaceous plants have soft, green, non-woody stems. These plants typically die back to the ground at the end of the growing season. For example, invasive orange hawkweed or invasive spotted knapweed are both herbaceous plants.
Orange hawkweed is a herbaceous plant.
Spotted knapweed is a herbaceous plant.
Woody plants, on the other hand, produce wood as part of their structural tissue, and have a hard stem. For example, the tree of Heaven, Scotch broom, and Himalayan blackberry are all considered woody plants.
Woody stems of Scotch broom plant
Tree of heaven (photo: R. Gardner, Bugwood.org)
Himalayan blackberry (Photo: L. Scott)
Most often, herbaceous perennial plants will be said to “die back” in the fall and return in the spring. Woody plants may also “die back”, although for the most part, their above-ground stems and branches will remain.
Do all plants die back in the winter?
No! Not all plants die back in the winter. Some plants are annuals, which means that they complete their full lifecycle in one season and die in the fall/winter (although if they produced seeds, their seedlings will sprout next year). Only biennial and perennial plants can die back.
Nearly all biennial and perennial plants go dormant in winter, but some plants can keep their leaves all year round. These are called evergreen plants.
Evergreen plants keep their leaves year-round. In the Sea to Sky region, common evergreens include pine, fir, and cedar trees. Instead of broad, flat leaves, these trees have needles or scales—an adaptation that reduces their surface area, helping them retain water during the winter. The needle shape also offers protection from wind, snow, and ice, allowing evergreens to survive the cold months without shedding their leaves.
This native Western red cedar has scale leaves and is an evergreen tree. (Photo: Wikimedia Commons)
English ivy is an invasive evergreen known for its waxy, leathery leaves. It is remarkably resilient and can withstand winter conditions.
English ivy leaves
Deciduous plants lose their leaves in the fall and winter. Their broad, flat leaves make them more vulnerable to water loss and freezing, so dropping them helps the plants conserve energy and survive harsh winter conditions.
There are many native and invasive deciduous plants in the Sea to Sky region. One example is the invasive tree of Heaven.
Tree of heaven is a deciduous tree (Photo credit: R. Gardner, Bugwood.org)
Plants in the Fall
As the seasons shift, many plants begin to change. Some die back completely underground, others lose their leaves, while a few stay green all year long. How a plant behaves in the fall and winter reveals a lot about how it grows—and the special adaptations that help it survive harsh conditions.
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