The Myth of the Indoor Bonsai

Sitting on the magazine table, under the glare of the institutional lighting in my dentist’s office, a Juniper bonsai was proudly displayed. I mentioned that it wasn’t getting much light to the receptionist and she assured me not to worry because it was, after all, an indoor tree. Too bad she had no idea that there is no such thing. All trees are outdoor trees.

It probably seems like a foolish point to make, but if there is any hope that you’ll ever understand more about the care and nurturing of your bonsai, it’s important to make a clear distinction between an indoor tree and one that just can’t handle the cold. Sometimes the heat can actually be the problem, but take it from me, a resident of Toronto, Ontario. The real defining factor is the cold. But the question is “How cold?”

When you’re looking at “indoor” bonsai trees you need to try and learn a little more about them than that. Tropical trees don’t have warm and cold seasons, but they do have wet and dry seasons. They have times of active growth, flowering, fruiting and they have a time that they rest. Many warm weather trees are not leafed out year round. The Barbados Cherry (Malpighia pendiculata) for example, will drop its leaves in the winter. What no tree has is a natural environment that mirrors a coffee table in a dimly lit room.

What are even more perplexing are the trees that are very accurately labeled as outdoor trees. Not only is there a huge variation between the relative degrees of hardiness among outdoor bonsai, there isn’t one that will make it though a subzero winter without some protection.

But I’d rather focus on the warm weather trees and what you can do to keep your bonsai healthy and thriving. Do them a big favor and after you’ve done some research on their temperature range and any wet/dry or cool/hot variation they need – let them spend as much time as possible outside. Even though it will mean more work for you to watch out for bugs, and squirrels and hot sun, wind and the odd soccer ball.

Taking a tree like a Chinese elm outside for the summer and allowing it to run through the fall, pretty much guarantees that it will drop its leaves and go dormant for the winter. On the other hand, left indoors all year round your Chinese Elm will be evergreen, but it won’t have the vigor that the deciduous version enjoys. Another tree that is regularly brutalized by being seen as an indoor bonsai is the ubiquitous Juniper procumbens bonsai. They can survive inside for a long time with the right care, but for the most part they’re slowly dying from the minute they’re brought into the average home which is hot, dry with bad air circulation and not nearly enough light.

Every tree is different. Learn more about where your tree lives in the wild. Is it a tropical rainforest diva, or a scrappy little subtropical tree that can handle some temperature fluctuations? You might also find that the tree a Southern California grower confidently labels as outdoor absolutely needs to come inside for your winter. Start here. With an eye on the warmest and coldest temperatures that it will happily endure, (modified to accommodate that little pot it’s in rather than the ground) take the extra steps to give it the longest dose of outdoor weather that you can reasonably provide. Your tree will love you for it – as long as you don’t forget about it.

The Black Olive Bonsai grows best where it can get lots of heat. As a Bonzi tree you must keep it from any threat of frost or you’ll lose it.