Watering Bonsai Trees 💦

Watering is a very important pillar in bonsai care, considering that being in pots with limited space, resources will also be limited.

Is it good to always water with osmosis water?

Osmosis water has a minimal concentration of minerals. Most bonsai species need minerals to develop correctly, so if we always water with osmosis water, we must provide these nutrients with fertilizer.

Some species like acer palmatum or Siberian elms are very sensitive to an excess of dissolved minerals like lime. Their roots have very small pores that can be easily clogged if we water with hard water. In these cases, we will be forced to water with osmosis water unless our tap water is already soft.

Other species like ficus or Chinese elms on the other hand, will not suffer from this problem and will give us the freedom to water with harder water.

If we live in the center of Spain, like Madrid, we will already have very soft water. If, however, we live in the Mediterranean part, like Barcelona or Valencia, we will have much harder water, which may require us to get an osmosis system if we want to grow certain species.

In the end, the best way to achieve success is to adapt to which species we can grow without it being a headache when it comes to providing quality watering for our trees.

How often should I water my bonsai?

There is no exact frequency. It will all depend on the type of substrate, the species, the environment… Generally, we should aim for the top part of the substrate to dry out between waterings. To do this, we must use very draining substrates that also retain some moisture inside.

It will also depend on the stage the specimen is in. For example, an acer palmatum that has not yet budded will not evaporate as much water as one that already has fully formed leaves.

Similarly, if the environmental humidity drops, the temperature rises, and if it is windy, we must increase the watering frequency to the point of having to water up to three times a day.

Should I use drainage plates?

We do not recommend it as it is good for the substrate to dry out. If we use plates, water will always remain in the plate, which can cause the roots at the bottom to always be wet, and that could attract fungi and other diseases.

If we want to use plates, it is best to remove them during watering or empty them without leaving water for a long time.