How To Water My Bonsai Tree

Knowing how to water a bonsai tree properly is without a doubt the most important part of keeping the tree alive and thriving. If over watered, the tree will get root rot. If under watered, the foliage will dry up and fall off. In this article I show you exactly how to water a bonsai tree and find the perfect routine.


The most important part in watering a bonsai tree is checking to see if the tree actually needs watering. If the tree gets over watered or under watered over a long period of time, it’s going to have serious health problems. There is a very simple technique to knowing exactly when and how to water your bonsai tree, let’s find out more…


How Often To Water Your Bonsai Tree


Unfortunately bonsai trees don’t have a set time to be watered and giving a broad answer of exactly when to water a bonsai tree is impossible. The frequency a bonsai tree needs watering can depend on a huge amount of factors including:


  • The species of tree
  • Bonsai pot size
  • Soil quality and mix
  • Climate
  • Time of year
  • Amount of foliage


As you own a bonsai tree for a period of years you’re going to know exactly how your trees respond to certain amounts of watering and it’s going to make the process of watering extremely simple. This has happened with all of my trees so far, I know how often my Chinese Elm needs watering in the winter compared to my Juniper.


A general rule of thumb will be to check to see if the bonsai tree needs watering at least once per day. This doesn’t always mean you will water the tree daily, just checking to see if it needs to be watered. I would advise checking twice per day, once in the morning and once in the afternoon during the growing months of summer, as most trees are going to get very thirsty and soil tends to dry out very fast.


How To Water A Bonsai Tree, Step By Step Guide –


There are a few very simple methods to watering a bonsai tree properly that have been used successfully for a very long time. I am going to break down the simplest way for beginners to ensure their tree is properly watered.


1. Firstly you need to check if the tree needs watering, to avoid over-watering the bonsai. Push your finger about 3 cm into the top soil. If it feels dry or barely moist, it needs watering. If the soil feels wet or very moist, the tree does not need to be watered yet, check again in 12 hours.


2. From a low height, start pouring either rain or tap water over the soil, evenly covering the whole of the bonsai pot. You’ll want to pour slowly and keep pouring until water is running well out of the pots drainage holes.


3. Stop watering your tree and let the pot drain for the next 3 minutes. 


4. Repeat step 2. again, evenly watering the soil once more.


5. Let the bonsai tree sit and drain fully for the next 10-15 minutes. 


6. Fill the humidity tray with water, to provide extra humidity to indoor grown species.


This is the most effective way to water a bonsai tree properly, ensuring the roots and soil is thoroughly watered. This process should be done whenever the soil is feeling dry. If done too often, with already wet soil, the roots are going to struggle to get oxygen. This over the long term causes ‘root rot’, where the root system is going to start dying and rotting away.


You’ll notice I haven’t included misting the foliage on here, as for most bonsai it is pointless. I would only advise watering if you have a species that produces flowers, like the crab apple. For more information about why you shouldn’t mist a bonsai tree, read my article!


The Best Time Of Day To Water A Bonsai Tree


There is not a preferred time of day to water a bonsai tree but it’s best to avoid watering in the evenings as it can freeze as the temperature drops going into the night. Finding what works for you and your busy schedule is going to be the most important thing to think about, making sure you don’t go a day without checking on your trees.


I personally like to check my bonsai trees first thing in the morning, about 7 am, then once more at around 4 pm. There is no real logic to this, it just suits my schedule perfectly and ensures my bonsai trees are never under-watered. If the only time you can water a bonsai tree is at 9 pm, that’s when you should be watering your tree. The way I like to look at it is any watering is better than no watering. If the tree was growing out in nature, there is never an exact time of when it should be watered, so there doesn’t need to be when growing in a tiny pot.


Problems Caused By Watering


Watering is the most important part of keeping any type of bonsai tree alive but it can also be the cause of some very serious problems. By not getting watering quite right it’s very easy to either give the tree too much water, or too little. These can result in foliage turning brown, leaves falling off, leaves turning yellow, a lack of growth and actually death as well if untreated.


Under-watering –


Under-watering is a huge problem for bonsai trees and can lead to a lot of serious problems or even the death of the tree. This is common with beginners or people who have received a bonsai as a gift and simply forget to water the tree. As trees are in such small pots and have access to such a small amount of nutrients, it’s extremely important to keep a close eye on the soil moisture to avoid under-watering.

The most common symptom of under-watering a bonsai is the leaves turning brown, dry and crispy, leading to them falling off. This can mean a few things but is usually associated with the tree being under-watered for a long period of time. At that stage the tree can usually be saved and nurtured back to full health but if it left untreated, it will lead to the death of the tree.


Some species of tree can tolerate under-watering very well, making them perfect for beginners. One on the top of my head is the Jade bonsai. This species stores a huge amount of water in the branches and trunk, meaning it can be under-watered for a long time without perishing. For a beginner, I would advise picking a species that can tolerate a bit of a lack of care for short periods. For more information on trees perfect for beginners, have a read of my article!


Under-watering can be avoided by routinely checking the soils moisture content, once or twice per day. This simple procedure means it’s impossible to actually not provide the tree enough water. Another option is to add something like moss onto your bonsai soil as this will increase the soils water retention properties a little, meaning you may be able to get away with watering the tree less. For information on growing your own bonsai moss, read here!


Over-watering –


Over-watering can be as fatal to a bonsai tree as under-watering, although it’s usually done with the best intentions. When people first get a bonsai tree they usually care for it too much as it’s new and exciting, which can lead to it being over watered. When over-watered, a bonsai tree will start slowly dropping leaves, getting softer and the roots will start rotting away, eventually leading to the death of the tree.


This issue is usually caused by one of three main reasons:


1. Not understanding when how often to water your bonsai tree – The main cause of over-watering in a bonsai tree is people simply not understanding the requirements of their tree. All trees are completely different and will require vastly different watering routines. Some species are very thirsty, some are not. The amount of water needed by a bonsai tree depends on a huge amount of different factors including soil mix, pot size, tree age, species, growing conditions and time of year.


The only way to effectively water your bonsai tree and ensure you aren’t over-watering is to actually check the soils moisture content daily, instead of watering regardless. Only watering when the soil is drying out, rather than still wet will ensure the roots get enough oxygen and won’t be as likely to rot away. I have an article here you might find really useful: 5 Must Know Tips For Watering A Bonsai Tree.


2. Having the wrong soil mix – Bonsai trees are not like houseplants, they don’t do well in standard soil that retains a crazy high amount of water. A lot of cheaper bonsai trees purchased online will be potted in cheap, high retention soil which will lead to over-watering. These trees need a perfect mix of Akadama, Pumice and Lava Rock, combined to make a soil mix that has the perfect level of water retention and drainage.


If the soil retains too much water, this clogs the air pockets in the soil, meaning the roots are starved of oxygen. When this happen, the roots die and start to rot away, infected the rest of the tree. This can and will be fatal to the bonsai tree unless treated fast, so keeping a check on the soils moisture levels is very important.


To avoid the issue of having the wrong soil mix, you can create your own for relatively cheap. I have a full step by step guide on creating bonsai soil here, so give it a read if you’re interested. No matter how well you care for a bonsai, if it’s grown in the wrong soil eventually it will die off, there’s no avoiding it.


If you think you have over-watered your bonsai tree, it’s best to let the soil dry out and think about repotting the tree if it’s serious root rot. When repotting the tree, ensure you are pruning all of the dead roots back, allowing for new root regeneration in the correct soil mix. For more information about repotting a bonsai tree, check out my article.


3. Not having drainage holes – Although this issue is less common, it will still lead to over-watering and the death of your beloved bonsai. Some bonsai pots don’t actually come with drainage holes. This means whenever the tree is watered, no water is allowed to escape and the soil retains 100% of it. This leads to the roots constantly sitting in water, being starved of oxygen and rotting.


This isn’t so common anymore, it only really happens with extremely cheap trees purchased online, or trees that have been planted in old reused pots from succulents or cacti. To get round this issue, ensure your bonsai pot has one or two large drainage holes, covered by a fine mesh sheet. This allows excess water to drain out of the pot, leading to the soil not being too saturated. Choosing the right bonsai pot is very important, have a read of my article here for help choosing the perfect pot.


Final Thoughts


Knowing exactly how to water a bonsai tree is key to the tree surviving over the long term. Although watering a tree isn’t the hardest aspect of bonsai, making sure you are steering clear or under-watering, over-watering and thoroughly watering the soil are all extremely important to the health of the tree.


Having an exact method for how you water a bonsai tree is the best way to ensure you are meeting all of the trees needs. Slotting the correct watering routine into your daily routine is sure to keep your tree collection alive for years to come! If you have any questions or need anymore information, feel free to leave me a comment and I’ll get back to you!


Relevant Articles – 8 Most Common Indoor Bonsai Trees / How To Care For An Indoor Bonsai Tree

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