Watering bonsai: when, how often & how much?

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For the bonsai to thrive, the right water supply is crucial. Here you can find out what you should consider when watering bonsai.

Water the bonsai with a small watering can
Bonsai need special attention when it comes to water [Photo: Karin Lirapirom/ Shutterstockc.om]

Due to the pot culture there is hardly any room for error when caring for a bonsai. Casting in particular can quickly become a source of error here. Because the limited shell volume and the rather permeable bonsai soil make frequent watering necessary - and too frequent watering a problem. How often watering ultimately has to be done depends on several factors, which we would like to present to you below.

Like any plant, the bonsai needs water to survive. Due to the isolated culture form of the bonsai in a bowl, meticulous attention must be paid to the need-based water supply. This is even more difficult with bonsai than with most other potted plants, because the pots usually offer very little substrate to store water. In addition bonsai soils consist to a large extent of inorganic materials and are poorly able to store water anyway. Bonsai have to be watered at relatively short intervals. But not only the watering distances and the watering method is decisive - also the choice of a suitable culture dish and a suitable one

bonsai soil is essential. We clarify all questions about watering bonsai.

tip: Unfortunately, enlarging the bonsai pot is not an option that could solve the watering problem. Because enlarging the root space would lead to strong growth, which is not typical for bonsai. Substrates that store too much water are also not a good idea: They lead to insufficient root aeration and thus quickly to a lack of oxygen in the roots and root diseases.

When should you water your bonsai?

With bonsai, the watering rhythm should be adapted to the individual plant. If you water without considering the bonsai, you run the risk of waterlogging or the substrate drying out completely with the pot culture. However, neither should ever happen. Therefore, you should water your bonsai as soon as the substrate has dried on the surface. In the case of conifers and succulents, the substrate can sometimes be a little drier. You can easily recognize the drying off by the lightening of the substrate or by simply touching it. It is best to check your bonsai substrate daily. Because especially in summer it can happen that you have to reach for the watering can several times a day. On hot days, only water in the morning or evening hours. Even in winter you should always keep the substrate moist. Here, however, watering intervals are much longer due to the reduced water consumption of the bonsai. Bonsai that overwinter in the garden are only watered on frost-free days. When a bonsai needs to be watered depends on the drought tolerance of the species, the substrate and the climate.

Bonsai landscape on wooden table
Due to the small substrate volume, a bonsai needs water particularly often [Photo: 3000ad/ Shutterstockc.om]

Summary: when to water bonsai?

  • Water as soon as the substrate has dried on the surface (check daily!)
  • Conifers and succulents are more drought resistant than deciduous bonsai
  • Keep substrate moist even in winter

tip: High quality bonsai soils are airy and still store and distribute the irrigation water effectively. Swellable clay minerals, for example, are responsible for this, which also absorb nutrients and release them when necessary.

How often and how much do you have to water bonsai?

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

  • Water requirements of the respective plant species: In general, coniferous trees are watered less. Depending on the substrate, let it dry 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 the water requirement is higher than in winter due to evaporation from sunshine and shoot growth. Here the plants rest and are therefore watered less. The following applies: the warmer the bonsai is in winter, the more water it needs in the dark season. Indoor bonsai that are in the heated apartment therefore need water regularly, even in winter.
  • water storage properties 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 irrigation water the tree loses through evaporation. Evaporation is highest on a sunny window seat.
  • surface of the planter: The surface of the plant pot also influences evaporation. The larger this is, the more water evaporates and it has to be watered more often.
Small bonsai
Of course, a small bonsai needs less water than a large outdoor bonsai [Photo: kathayut kongmanee/ Shutterstockc.om]

It is best not only to pay attention to the surroundings and that substrate of your bonsai. Also find out about your specific needs Bonsai Art regarding the water requirement in order to be able to plan your waterings better.

How is a bonsai watered correctly?

To water your bonsai properly, you need to completely soak the substrate. Proceed as follows when watering your bonsai:

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

Hard tap water should be avoided in order to avoid deposits on the roots and the vessel and an increase in the pH value. Alternatively, you can use the immersion method for smaller bonsai. To do this, immerse the bowl in a container of water for a few minutes until no more bubbles rise to the surface of the water. During this time, the substrate can absorb water well. Then drain off the excess water.

Tip: With strongly clayey bonsai soils you should always resort to the immersion method.

So that you can water your bonsai properly, your bonsai pot absolutely needs a drainage hole. Otherwise the water cannot run off and waterlogging forms. If waterlogging occurs, your bonsai will react with brown leaves that will be shed sooner or later and dead branches. You can find more reasons for leaf shedding in bonsai here. at Bonsai Specieswho come from tropical areas and are used to a humid climate, you should regularly reach for the water sprayer. How to increase humidity. In winter, this is particularly important for indoor bonsai to compensate for the dry heating air.

Water the bonsai with a spray bottle
Bonsai that are used to humid climates will appreciate an occasional misting to increase humidity [Photo: jayjued/ Shutterstockc.om]

Summary: watering bonsai how often and how much?

  • How often it needs to be watered depends on many factors, so keep an eye on your bonsai
  • Water soaking with soft tap water or rainwater
  • For substrates containing clay, use the immersion method
  • Spray bonsai that need high humidity regularly
  • Always use a bowl with a drainage hole to avoid waterlogging

However, bonsai need not only water but also nutrients to grow properly. Everything to the right Fertilizing bonsai you can read here.

Many thanks to Floragard for the support!