Bonsai Terrarium: The Guide for Beginners

A bonsai terrarium can be a real eye-catcher in any home. But how can you keep a bonsai in a terrarium? In order for the little tree to do well in your terrarium, you need to pay attention to the right composition of your substrate and also closely control the amount of water.

Important for your substrate are a good water-retaining property, fast drainage of excess water and a strong aeration. In this article, you will learn how to create all this.

What is a bonsai anyway?

Bonsais are in fact not a species nor a biological term.

It is a Far Eastern art form in which trees are kept as small and delicate as possible, for example, to be presented on a table. So, in pure principle, any tree, including domestic plants here, could be a bonsai tree.

Of course, some species are better suited than others. And we'll take a look at them now.

You'll find a lot more details in the article on general bonsai care and design.

Bonsai infront of white wall
A bonsai in front of a white wall. Source: piqsels.om

Choosing your bonsai

Bonsai trees can be divided into different forms. These differ in the attitude among other things in the amount of water they need and especially the temperature. Specifically, two varieties of trees can be selected for your closed terrarium. These are the tropical and the subtropical form.

Subtropical bonsais for your closed terrarium

Subtropical bonsais are native to southern Europe. Especially in the area of Italy and Spain you can find them. Examples are small olive trees (e.g. Olea europaea) or wild pistachios (e.g. Pistacia lentiscus).

Subtropical bonsai trees do very well at 20°C (i.e. room temperature) and thus fit wonderfully into your living room. However, keep in mind that they go into hibernation during the cold months, when they prefer it at around 10°C.

Here you can view subtropical bonsais.

The tropical form

Tropical bonsais originally come from China. However, there it is also not much warmer than here in Europe, which is why you with 20 ° C is still very well positioned.

Unlike subtropical species, tropical species usually don't require hibernation, so you can leave them indoors all year round.

Examples of tropical bonsai are the small-leaf Szechuan pepper (Zanthoxylum spec.) and the Chinese tiger bark fig (Ficus microcarpa). You can check them out here.

How to keep a bonsai in a closed terrarium

Whether you have a tropical or subtropical bonsai tree in front of you for your closed terrarium, it likes it warm and humid. The 20°C in your living room are optimal for him and it can be a few degrees warmer. So at least for now you don't have to worry about this.

In winter, when the temperature is below 10°C, you can place your closed terrarium with subtropical bonsai outside close to the house wall. There your closed terrarium will absorb some heat and will not be quite so cold.

You probably won't be able to put your bonsai in a refrigerator, because the glass of your closed terrarium will probably be quite large.

Three bonsais in contrasting shapes and colors in simple white pots. The pots are placed on a wooden bench in a glass greenhouse with a variety of plants and flowers in the background.
Three different bonsais in white pots

Bonsais need a lot of sunlight

Similar to succulents, bonsai need a lot of light to grow properly. If you want to keep your closed bonsai terrarium indoors, you should place it in a south or southwest window where the afternoon sun will arrive. Make sure you don't put your bonsai terrarium in full sun, but provide bright, indirect light.

The sun is strongest in the afternoon, giving the bonsai tree in your closed terrarium a lot of energy. You're good to go if you give your closed bonsai terrarium around 10 hours of sunlight every day. More is even better!

If your bonsai terrarium is left in full sun for a long period of time, problems may arise. The strong sun will cause a lot of water to evaporate from the leaves, making the bonsai very dry.

Although the humidity in your closed bonsai terrarium will also increase, it will harm the bonsai if this happens at the expense of its own water. In addition, the water on the pane can act like a lens and even burn holes in the leaves of your bonsai.

Alternatively, you can also think about fluorescent tubes or LEDs. They are by far not as strong as the sunlight and definitely do not burn holes in your bonsai. Of course, they also give him not so much energy. However, there are special grow lights that are designed specifically for plant growth. You can learn more about lighting in this article.

A bonsai in a closed terrarium
A bonsai in a closed terrarium

Bonsais in closed terrariums need a well-ventilated substrate

While bonsai like moist soil, it must not be soggy and have standing water under any circumstances. For the bonsai in your closed terrarium, it is even more important that you use a loose substrate with large pieces (e.g. expanded clay, stones, charcoal), in which the water can drain well into the false soil below.

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How you can mix a substrate in principle, I have already described in this article. You can use exactly the same methods here. The following materials are particularly suitable for bonsais:

Puffed clay and akadama are both made of clay and absorb water very well. You can choose one of them or use both. With them you get a water retentive property in your substrate.

Pumice, pebbles and volcanic stone are meant to make your substrate more coarse-grained so that water drains better into your fake soil. To hold everything together and help your bonsai root well, add potting soil. The Bonsai Empire recommends a different composition for deciduous and coniferous bonsai.

For deciduous trees, they recommend a mix of 2:1:1 akadama/pumice/lava granules, and for conifers, 1:1:1 of the same ingredients. To learn how to build the wrong soil for this, see this article.

Bent bonsai
Bent bonsai. Source: piqsels.com

Caring and cutting your bonsai

To keep bonsai small and manageable, they need to be pruned regularly. You may need to open your bonsai terrarium for maintenance every few months.

If you find that your bonsai is leaning too much to one side, you may need to trim a branch or pull it to another side with a ribbon. If this doesn't bother you, you can of course stop caring for your bonsai altogether and just let it grow.

In general, there are two types of pruning: the maintenance pruning and the aesthetic pruning. The maintenance pruning is used to control and promote the growth of the bonsai. You should do it in spring or summer when the bonsai is actively growing. You cut back the new shoots that have become too long or too dense.

Aesthetic pruning is used to give the bonsai a certain shape or to change it. You should do it in the fall or winter when the bonsai is dormant.

Here you cut the branches and twigs that do not fit the desired style or disturb the harmony. For both cuts you need sharp and clean scissors, specially designed for bonsai. You should always cut carefully and considerately, so as not to injure or weaken the bonsai.

A bonsai and several tools in a garden at sunset
An aesthetic bonsai with pink flower

Summary

Keeping a bonsai terrarium is quite possible. You just need to make sure that your substrate is loose and your bonsai is at a comfortable temperature. In summer you won't go wrong with your room temperature of 20°C. In winter, however, you will have to cool down closed terrariums with subtropical bonsai. Light is also important for your bonsai terrarium. It needs about 10 hours of sunlight a day, but it does not like to be in full sun, otherwise the bonsai will dry out too much.

By the way! If you like flowers more than bonsais, check out the article about orchids in a closed terrarium.

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