Everybody who has bonsai knows the worry at the end of winter. A tree is a little slow in responding to warmer weather. No bud is swelling. No green line is showing. Has the bonsai died over winter? This post is part of a series of posts exploring why bonsai die in winter. In this post: The effect of the sun and wind exposure, and how to avoid problems.
Why do bonsai get damaged by sun and wind in winter?
To understand what happens in winter to a tree standing in full wind and sun, let’s take a mental exercise. I think all of us have once had a cold drink with ice cubes in them. And as a kid many of us have played with the ice cubes: Using a straw you drink until an ice cube blocks the straw. You can then even lift the ice cube out of your drink. No drink enters the straw. Now let’s take this to your tree in winter. The sap in the tree is fluid, and evaporates. In the sun, branches warm up very rapidly, and in combination with the wind, the tree evaporates a lot more than in a sheltered position. However, the root ball of the tree is frozen: All the water is solid in the form of ice, and cannot be pulled into the roots of the plant. As such, the tree loses a lot of water, but is unable to bring water up. As a result, the tree slowly dries out.
What to do to avoid bonsai damage due to sun and wind in Winter
The easiest method to avoid desiccation of your tree in winter is to ensure they are not placed in the sun and wind. This is wat I do for the frost hardy species: They are in a sheltered corned in the garden out of direct sun and wind.