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big beautiful deciduous tree covered in snow and ice after a storm

If you're wondering what happens to them in the winter, you've come to the right place. Do they keep growing even when it's cold or do they hibernate like animals?

Here is our guide to the winter months of a tree's life, and the science of what happens to these magnificent plants.


Trees are still alive during winter. They're dormant, but they aren't dead, even though the leaves fall out and they look dreary. Wintertime is when trees gather abscisic acid at the base of leaf buds, which signals them to drop off.

The acid prevents cell growth, so the tree doesn't use nearly as much energy in the winter. It's similar to when animals hibernate.

Leaves dropping off a tree is called abscission. Another reason trees do this is so that they aren't using water. When leaves exist, they participate in transpiration, the process of allowing water to leave through the leaves' stomata.

As water exits through the stomata, the tree knows to send more water upward through the xylem. Because the water in the ground is frozen in winter, dropping their colourful leaves allows the tree to halt the water flow through the xylem.


Sometimes you can prevent tree dormancy in the winter. If your trees are potted or small enough, you just need to bring them inside and keep them at a regular temperature. Make sure they have plenty of light.

Be aware that eliminating the dormancy period can shorten a tree's life. Dormancy is an important part of a tree's natural life cycle. The season changes help trees reset and get ready for spring when they push out buds and new leaves.


Evergreen tree needles are covered in wax. The wax helps protect them from the cold, and it's also helpful for holding in water. Some trees, such as pine trees, can even still use photosynthesis to make food even in below-freezing temperatures.


Trees do not usually grow in winter. However, trees can protect themselves by way of supercooling, a process that allows them to withstand temperatures even down to -40°C.

To form ice or snow, water molecules need particles to attach to. Snow forms crystals because of the dust in the air. The fluid in trees doesn't have any particles in it, so it's not able to form crystals of ice. That's why, even though they're full of water, trees don't crack and break in the cold winter months unless a heavy snowfall or strong winds are at play.

Even in temperatures colder than -40°C trees can still avoid cracking. The fluid gets pushed in between the cells so that the cells can't get ruptured when it freezes.


Between the abscission or dropping of leaves, and changing into dormancy, trees experience a lot of changes in winter. These season changes are a necessary part of the tree life cycle. Yet hazardous damage to trees still happens in the winter. If you need some help with trees on your property in the Edmonton region, contact us today!


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