How to Overwinter Bonsai: Placement

The cold of winter is starting to set in.
Typically, the roots of trees anchored in the ground extend deep underground, so they don't require special protection against freezing in winter.
However, bonsai are planted in shallow pots, so their roots need protection during the winter months.
This journal offers advice to help your bonsai survive this winter and thrive next spring.

First, bonsai are trees that originally exist in nature.
Being moderately exposed to cold can also make them stronger.
Even in cold environments, they can survive the winter without issues if you take proper measures.

However, different species vary in their cold tolerance.
Conifers like pine and cypress are highly cold-hardy, while evergreens such as citrus and gardenia are less tolerant of cold.
Deciduous broadleaf trees like Japanese maple and zelkova fall somewhere in between.

Now, let's get into the specifics of overwintering your bonsai!

・Place in a winter shelter
First, prepare your winter shelter.
A “winter shelter” refers to protective equipment for sheltering bonsai trees during winter.
Any structure will do—prefabricated units, vinyl greenhouses, etc.—as long as it provides a closed, enclosed space protecting against cold winds, snow accumulation, frost, and frozen pots cracking.
Commercial vinyl greenhouses are perfectly suitable.
Styrofoam boxes or storage containers with lids can also serve as a mero.
After placing the bonsai in the “winter shelter”, do not leave it unattended. Check on it every 2-3 days.
If the temperature inside the “winter shelter” rises too much, the bonsai may suffer, so air exchange is necessary.
Furthermore, introducing fresh air also helps prevent mold.
On sunny days, open the “winter shelter”'s lid around midday.

・Indoor care
You can also overwinter it indoors.
However, avoid placing it in warm, heated areas.
It's important to overwinter it indoors in relatively cooler spots like unheated rooms or entryways.

Please overwinter them using one of the methods described above.
In the next blog post, I plan to discuss the timing and precautions for overwintering.

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