As the season turns towards winter, your bonsai tree will start preparing for the freezing weather ahead just like its big tree counterparts. Because a bonsai tree isn’t rooted in the ground, it is especially vulnerable to the extremes of winter and so some precautions must be taken. Your tree will be depending on you to help protect it through the winter.
Changes in Bonsai Foliage
If your tree is a deciduous tree, it will probably lose its leaves in the fall and go dormant. Some deciduous trees don’t lose their leaves annually (for example, many boxwoods will keep their leaves for more than a year).
If your tree is an evergreen, it won’t lose its foliage, but it may experience a change in color during the winter dormancy.
If your tree is a tropical, make sure to research what temperature ranges your tree will tolerate. Some tropical trees can handle temperatures around 40° F (4° C), but others will be stressed by such cool temperatures and prolonged exposure may eventually weaken the tree and lead to death.
Storing Dormant Bonsai Trees
Bonsai trees that are winter hardy need to go dormant in the winter. There are many methods of storing your bonsai trees during the winter. Some bonsai enthusiasts place their trees in a temperature-controlled environment, keeping the temperature around 34° F (1° C). Others place their trees in an unheated garage that is attached to their house (the garage usually receives residual heat from the house). Trees can be placed on the ground and mounded with mulch to protect the roots. You can also “plant” the whole container in the ground then lift it back up in the spring. The general idea is to keep the roots at a more stable temperature and not going through daily swings between freezing and thawing.
Bonsai Light Requirements in Winter
Bonsai trees need a minimal amount of light during the winter. In fact, too much exposure to winter sun can dry out the bare branches of deciduous trees and the foliage/needles of evergreens. Place your plant in a shady or partially shaded location through the winter if possible.
Watering Bonsai in Winter
Bonsai trees will still need a small amount of water in winter. Storing trees in an unheated garage and placing snow on the trees for watering is a great way to tend to your tree if you live in an area where it snows. When the snow melts, the trees receive water! Otherwise, you will want to lightly water when the soil becomes dry to the touch. No fertilizer is necessary in the winter since the plant is dormant and not actively growing.
Protect Your Bonsai from Wind
If you’re overwintering your bonsai trees outdoors, instead of in a garage or other shelter, it’s a good idea to place your tree where it can get some protection from strong winds. The east side of a wall or fence provides a windbreak from cold westerly winds.
At some point, your tree will need to be repotted. Repotting is most successful when done early in the spring. That makes winter the perfect time to go online to shop for a container, view instructional videos, locate a bonsai club or seek out a class to learn more about how to repot bonsai trees. As soon as the weather warms and spring growth begins, you’ll be ready to go!
Thinking about adding a tree to your collection? Many folks try to have at least one deciduous tree, one evergreen tree and a tropical tree or two in their bonsai tree collection. That way they always have a tree to work on no matter what the season. Learn more about some especially easy trees for use in bonsai in our article, 10 Beginner-Friendly Bonsai Plants.