Watering Bonsai: How Much And How Often To Water The Small Tree?

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For the bonsai to thrive, the right watering is crucial. Here you can learn what you should pay attention to when watering bonsai. Due to the shell culture, there is hardly any room for error when caring for a bonsai. Watering in particular can quickly become a source of error here. This is because the limited shell volume and the rather permeable bonsai soil make frequent watering necessary – and even too frequent watering a problem. How often watering is ultimately necessary depends on several factors, which we would like to present to you in the following.

Like any plant, the bonsai needs water to survive. Due to the isolated cultural form of the bonsai in a bowl, meticulous attention must be paid to watering as needed. This is even more difficult with bonsai than with most other potted plants because the bowls usually offer particularly little substrate as a water reservoir. In addition, bonsai soils consist to a large extent of inorganic materials and can store water poorly anyway. Thus, bonsais must be watered at relatively short intervals. But not only the watering intervals and the watering method is crucial – the choice of a suitable culture tray and a suitable bonsai soil is also essential. We clarify all questions around the watering of bonsais.

Tip: Unfortunately, increasing the size of the bonsai bowl is not an option that could solve the watering problem. This is because enlarging the root space would lead to – bonsai-untypical – strong growth. Substrates that store water too well are also not a good idea: they lead to low root aeration and thus quickly to oxygen deficiency at the root and root diseases.

When should you water your bonsai?

For bonsai, the watering rhythm should be adapted to the individual plant. If your water without taking the bonsai into consideration, you risk waterlogging or the complete drying out of the substrate particularly quickly in the case of tray culture. However, both should never happen. Therefore, you should water your bonsai as soon as the substrate has dried superficially. With conifers and succulents, the substrate can also be a little drier at times. You can easily tell when the substrate has dried by the way it lightens or by simply feeling it.

It is best to check your bonsai substrate daily. Especially in summer, it can happen that you have to water several times a day. On hot days, water only in the morning or evening hours. In winter, too, you should always keep the substrate moist. Here, however, watering intervals are much longer due to the reduced water consumption of the bonsai. Bonsais that overwinter in the garden are only watered on frost-free days. When a bonsai needs to be watered thus depends on the species’ drought tolerance, the substrate, and the climate.bonsai-landscape

Summary: Bonsai when to water?

  1. Water as soon as the substrate has superficially dried (check daily!).
  2. Conifers and succulents are more drought-resistant than deciduous bonsais
  3. Keep substrate moist even in winter
Tip: High-quality bonsai soils are airy and still store and distribute irrigation water effectively. This is due, for example, to swellable clay minerals, which at the same time also absorb nutrients and release them as needed.

How often and how much you need to water bonsai?

So for the watering interval, there is no fixed period. Rather, the length of time until the next watering of your bonsai depends on a whole series of factors:

  • Water requirements of the respective plant species: in general, conifers are watered rather little. The rule here is, depending on the substrate, let it dry out as much as possible.
  • Growth rate and age of the plant: The faster your bonsai grows, the higher the water consumption. Older bonsai grow much slower than younger plants and therefore need less water.
  • Season and temperature: In summer, water requirements are higher than in winter due to evaporation from sunshine and shoot growth. Here the plants are dormant and therefore watering is reduced. It is true that the warmer the bonsai is in winter, the more water it needs even in the dark season. Indoor bonsai, which are located in the heated apartment, therefore need regular watering even in winter.
  • Water storage properties of bonsai soil: the higher the proportion of organic substrate, the higher the water storage capacity. This also extends the watering intervals.
  • Size of the plant: A large bonsai has more biomass that evaporates water compared to a small bonsai. As a result, the basic water requirement is also higher.
    Location: the sunnier your bonsai is, the more watering water is lost to the tree through evaporation. Evaporation is highest in a sunny window spot.
    The surface of the planting tray: The surface of the planting tray also has an influence on evaporation. The larger this is, the more water evaporates and it must be watered more often.

It’s best to pay attention to more than just the environment and substrate of your bonsai. Also, learn about the specific needs of your bonsai species in terms of water requirements to better plan your watering.bonsai-small

What is the proper way to water a bonsai?

To properly water your bonsai, you need to completely saturate the substrate. Follow these steps when watering your bonsai:

  • Always use rainwater or soft tap water at room temperature.
  • Water with a watering can until the water flows out of the bottom of the tray.
  • Repeat the process after a few minutes.


Hard tap water should be avoided to prevent buildup on the roots and the container, as well as an increase in pH. Alternatively, you can use the immersion method for smaller bonsais. This involves immersing the tray in a container of water for a few minutes until no more bubbles rise to the surface. During this time, the substrate can soak up well. Then let the excess water drain off.

Tip: High-quality bonsai soils are airy and still store and distribute irrigation water effectively. This is due, for example, to swellable clay minerals, which at the same time also absorb nutrients and release them as needed.

In order to water your bonsai properly, your bonsai tray absolutely needs a drainage hole. Otherwise, the water will not be able to drain away, and waterlogging will form. If waterlogging occurs, your bonsai will react by dropping brown leaves and dead branches sooner or later. You can find more reasons for leaf drop in bonsai here. For bonsai species that come from tropical areas and are used to a humid climate, you should regularly reach for the water sprayer. This way you will increase the humidity. In winter, this is especially important for indoor bonsais to compensate for the dry heating air.

Summary: Bonsai how often and how much watering?

  • How often to water depends on many factors: Therefore, keep an eye on your bonsai.
  • Water soaking with soft tap water or rainwater.
  • Use immersion methods for clayey substrates.
  • Spray bonsai that need high humidity regularly.
  • Always use a tray with a drainage hole to avoid waterlogging.

However, bonsais need not only water but also nutrients to grow properly. You can read all about the proper fertilizing of bonsais here.

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