Even if you grow your bonsai trees indoors all year round, there are definite seasonal changes and understanding them and how those changes affect your bonsai. How you care for your tree(s) can be the difference between a tree that is thriving next spring and one that is not.
Of all the trees, I think that junipers, jades and black olive are the most affected.
If you keep your trees outside in the summer, the first factor you need to deal with is the change in conditions from outside to in. If I had written this post about 2 months ago, you could have started in August with gradually bringing your tree inside for a few hours each day and overnight to help cushion the change. Maybe some of you already did! But if you're seeing the signs of frost on the immediate horizon and realize your trees have to come in NOW- then sorry for this late article.
As is the case with almost any sudden or dramatic change in growing conditions- your trees will likely drop leaves and for some trees - like chinese elm, pomegranate and bouganvillea- this leaf drop might be a signal that your tree is ready to shut down for the next month or so and take a nap (see Winter Dormancy)
For others its just a bit of grousing. But please understand that winter in Canada is not a season for rapid growth and almost every tree will be slowing down- often a lot.
Light. The sun is lower in the sky than it's been over the warmer months. Have you noticed that warm, rich yellow tone that the light takes this time of year. It's beautiful - unless you're trying to find a golf ball, then it's a pain. The light is not as strong and the day length is shorter.
What does it mean for care?
The spot where you tree sat in the spring and summer and got plenty of light might need adjustment. If you can't move your tree to another place in the house then supplemental lighting might be in order. Not to worry- some plant lights are quite inexpensive and not even ugly. Here's an example
In reduced light black olives will often stop growing and drop leaves (not dead- just sulking). Some trees will show elongated internodes ( more stem between leaves- best known as getting "leggy"). Jades will get leggy, refuse to back bud and even drop leaves.
Less light slows growth and slower growth means you tree needs less water.
Next article - Air Circulation - The Good, the Bad and (you guessed it) the Ugly