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How Often To Water A Bonsai: Learn This Now

How Often To Water A Bonsai: Learn This Now
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One of the most important aspects of bonsai tree care is watering, as proper hydration is essential to keeping your tree healthy and strong. However, many bonsai enthusiasts struggle with finding the right balance when watering, leading to issues such as overwatering or underwatering.

In this article, we will explore the topic of how often to water a bonsai tree in detail, providing you with the information you need to keep your tree healthy and flourishing. Whether you're a seasoned bonsai enthusiast or just starting out, understanding bonsai tree watering needs is essential to the success of your bonsai tree journey. So, let's dive in and learn more about watering your bonsai tree.

Environmental Factors That Affect Watering


Trees lose water through evapotranspiration, where water is converted into gas and released into the air. The amount of water lost by a tree increases with wind speed. Therefore, on a cool and windy day, it's easy to underestimate how much water your trees need because of the absence of direct sunlight. However, strong winds can cause trees to dry out quickly, so it's essential to keep an eye on their water requirements.


Sunshine and heat can increase the water requirements of your trees. This is applicable even to bonsai that are kept in shade, as the increased heat causes greater water loss through evapotranspiration.

Since trees depend on water as their cooling system, it's important to ensure that they receive adequate water on hot and sunny days. Pay attention to your trees' water needs during such times to prevent dehydration.


It's obvious that if it's raining, you're not going to need to water your trees. However, if you live in a very wet climate you need to be even more aware of the levels of rainfall your trees are exposed to.

Overwatering due to rain over the course of autumn, winter and early spring can be very detrimental to trees that havea weakened root system. Consider putting vulnerable trees under a rain shelter to control the amount of water they receive.


The rate at which your bonsai tree dries out depends on the size of its container. Generally, a smaller container will dry out faster than a larger one, which may pose a challenge in taking care of your bonsai tree.

However, it is not always advisable to use a bigger pot for your bonsai tree since excessive watering can be just as detrimental as under-watering, as explained previously. The ideal container size for your bonsai tree depends on various factors like the species and size of the tree, the amount of foliage it has, and the condition of its root system. Ultimately, the container should fit the tree perfectly to ensure proper watering.


Making sure that the roots of your bonsai tree have enough oxygen and air is just as important as ensuring that it is watered. As bonsai trees have limited soil space, it is essential to optimize the area to promote healthy root growth.

If you are new to bonsai, it's worth noting that the most robust roots grow in an aggregate soil mix that has good drainage and many pores to allow air to circulate through the soil system. The optimal soil mix will depend on various factors such as the species, environment, and available components. In the Western world, the common soil mix comprises pumice, lava rock, and akadama, although different substrates can be experimented with to achieve the best results for your environment.

Using general-purpose compost for your bonsai trees will likely lead to water being retained for an extended period since it lacks the free drainage provided by aggregate soils. This can cause stagnant water in the pot, impeding root growth and promoting harmful organisms that lead to root rot and eventually kill the tree. If the soil mix remains too damp, it is advisable to repot the tree.

Bonsai Species And Watering

Different tree species have different water requirements. Deciduous trees, which have thin cuticles on their leaves and a large surface area, tend to pull water from root to leaf quickly and prefer wetter soil than conifers. Deciduous trees lose their ability to move water in winter when they shed their leaves, so their watering requirements decrease more than conifers during this season.

Deciduous conifers like larch and Dawn Redwood require more water than regular conifers. Among conifers, species like Spruce and Fir prefer wetter soil, while Junipers and Pines prefer more air in their system and can be allowed to get a bit drier before watering.

Tropical species such as Jade generally require less watering than deciduous or coniferous trees.

How To Tell When Your Bonsai Needs Water

Watering is considered to be the most important aspect of keeping a bonsai tree alive. In fact, it is often said that watering is the first thing you learn and the last thing you master in bonsai. If you miss a watering on a hot day, or if you leave your trees in the care of someone who neglects them while you're on vacation, there's a high chance that your bonsais will die.

On the other hand, overwatering your bonsai can also be detrimental to your tree's health. It can lead to a slow and prolonged deterioration of growth and aesthetics, which could eventually lead to the death of the tree.

However, watering a bonsai tree doesn't have to be complicated. While there's no hard and fast rule for how often you should water your tree, it generally depends on the species, environment, and container. But there is one key rule you can follow: only water your bonsai tree when the soil is dry.

Of course, there are exceptions to this rule, and compromises may need to be made based on your lifestyle and how often you can check your trees. But ultimately, the most important thing is to ensure that the soil in your bonsai container is not consistently damp, as this indicates that the tree has enough moisture to sustain itself.

Moss and bonsai watering

Moss can serve as a useful indicator for watering. Since the top dressing is constantly drawing water up through the soil, the presence of moisture in the moss indicates there is enough water in the system. When the top dressing begins to dry out, it's time to consider watering your bonsai. This method can help you monitor the soil system effectively.

Signs Of Overwatering Bonsai

Overwatering is one of the most common mistakes made by bonsai enthusiasts. It's important to understand the signs of overwatering so you can adjust your watering routine accordingly and prevent damage to your bonsai.

  • Yellowing Leaves: If you notice the leaves on your bonsai turning yellow, it could be a sign of overwatering. This is because the roots of the plant become waterlogged and can't absorb nutrients properly.
  • Wilting Leaves: Overwatered bonsai trees may have leaves that are wilting or drooping. This is because the roots become deprived of oxygen due to being in water for too long.
  • Fungus and Mold Growth: Overwatering can create a damp, humid environment that's perfect for fungus and mold growth. If you see any white or black spots on the soil or trunk of your bonsai, it could be a sign of overwatering.
  • Root Rot: One of the most serious consequences of overwatering is root rot. This occurs when the roots are constantly in water and begin to rot. The first sign of root rot is usually a foul smell coming from the soil.
  • Slow Growth: Overwatering can also slow down the growth of your bonsai tree. If you notice that your bonsai is not growing as quickly as it should be, it could be a sign of overwatering.

If you see any of these signs in your bonsai, it's important to adjust your watering routine to prevent further damage. Allow the soil to dry out a bit between waterings and ensure that your bonsai is planted in well-draining soil.

Signs Of Underwatering Bonsai

Underwatering is a common issue in bonsai care that can quickly lead to serious problems if not detected and corrected in time. In this section, we'll go over some of the most common signs that your bonsai is not getting enough water and what you can do to address the issue.

  • Wilting leaves: When a bonsai is underwatered, its leaves may start to wilt and droop. This is because the leaves hold their shape through the presence of water in their tissue. When they are dehydrated, they wilt, which reduces water loss by closing the stomata through which water evaporates on the leaves.
  • Yellow or brown leaves: When a bonsai is underwatered, its leaves may turn yellow or brown and become brittle. This is because the plant is not getting enough water to maintain its normal functions, including photosynthesis.
  • Slow growth: If your bonsai is not growing as quickly as it should, it could be a sign of underwatering. This is because water is essential for plant growth, and without enough of it, your bonsai may struggle to develop properly.
  • Very dry soil: If the soil more than an inch down in your bonsai pot feels dry to the touch, it is likely to be a sign that your plant is not getting enough water.
  • Leaf drop: In severe cases of underwatering, your bonsai may start to drop leaves. This is because the plant is shedding its older leaves in order to conserve water for more important functions.

Bonsai Watering Tips And Mistakes

Watering on a schedule

One of the most common mistakes made by beginners is to water their bonsai trees on a strict schedule. While it may seem like a good idea to water your trees every day or every other day, this usually results in trees being overwatered, which limits root growth and slows development of the tree. Bonsai trees should be watered when they need it, not on a schedule. How often you water your bonsai will depend on a number of factors, including the type of tree, the size of the pot, the temperature and humidity levels in your environment, and the time of year.

Not soaking the rootball

When watering a bonsai tree, the entire rootball should be saturated with water. This means that you should water your tree until water starts to come out of the drainage holes at the bottom of the pot. The danger of overwatering comes from a chronically wet soil state. If you just sprinkle the top of the soil, the core of the rootball can remain dry which leads to root death. To ensure that your tree is getting enough water, you can also check the soil moisture level by sticking your finger about an inch into the soil. If the soil feels dry, it's time to water your tree.

Asking neighbors or friends to water bonsai when on holiday

If you're going on vacation, it's important to make sure your bonsai trees are properly watered while you're away. While it may be tempting to ask a neighbor or friend to take care of your trees, I have found them to often not be very reliable unless.

Once of the best things I have bought for managing my bonsai was an automated hose timer hooked up to a regular garden sprinkler. Your neighbor may forget to water your trees or not give them enough water. Instead, it's better to invest in an automated watering system that you can set up to water your trees while you're away. Your neighbor can then just drop in to make sure all the trees are getting access to water. There is no danger of overwatering over the course of a short holiday - it takes months. A tree can die in a day from underwatering, so when you're not there it's better to play it safe.

The timer I uses connects to Wifi and notifies me when it switches on, which gives me piece of mind when I'm not at home.

Save time by finding marker trees

If you have lots of bonsai trees, it can be time consuming checking each one for water. To make things easier, you can find two or three "marker" trees that need to be watered the most in your garden. These can be good time savers, because if they don't need to be watered when you check, it's unlikely that other trees in the garden will need watering either.


In conclusion, the watering needs of bonsai trees are influenced by several factors such as wind, sun, rain, and the species of the tree. Watering a bonsai tree is crucial to keeping it healthy, but overwatering or underwatering can have detrimental effects. Only watering when the soil is dry is a good rule of thumb, but it is important to consider the species, environment, and container of the bonsai. Different species of bonsai trees have varying water requirements, and it is important to understand them to keep the tree healthy. Additionally, moss can serve as a useful indicator of the moisture level in the soil, and it is important to pay attention to any signs of overwatering or underwatering to adjust the watering routine accordingly.

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