Updated: Jan 23
One of the most asked questions among Bonsai Beginners is "How Do I Water My Bonsai Tree". It is very easy to see the information given as conflicting but if you understand the "Why" rather then just following the "How To" you will have a better understanding.
So lets tackle this together.
Bonsai Watering Routine
Now that headline is slightly deceptive because there is actually no set routine for watering a bonsai tree but it is a good headline to use so we can debunk it straight away.
The reason there is no Routine for watering a bonsai tree is because we go through 4 different and unique seasons and each species of trees has a different need for water and tolerance to it. For example we have Junipers here in our Garden and they really dont like to be wet for long, But on the other hand we have Tea Trees which are native to Australia and grow near bodys of water so they LOVE water and cant get enough. If i was to water a Juniper like i water my Tea Trees i would hate to see the Results....
This comes back to my reasoning to understanding the "Why" rather then just following a "How To" Guide. There can not be 1 Simple "How To" guide on watering as it is different from tree to tree and zone to zone.
"But your article is named How To Water A Bonsai Tree"
Ok you got me... But the reason i named it that is i want people who are searching that term to end up here and get the right knowledge rather then ending up on an actual " How To " Guide with little useful knowledge.
Now that we have that out of the way lets get back to the Watering Frequency.
How often you water your Bonsai Tree doesn't just come down to Species but also comes down to Seasons. In winter we dont water as often as a lot of the trees are dormant meaning they are essentially sleeping through the cold and living off stored energy they saved through out summer and autumn. How ever they still need water during this period, Just not a lot and not as often as the soil does not dry out very quick in winter and you will find out why that is bad later in this article.
In summer we need to water more often as the high heat drys soils out quickly and trees transpire a whole lot more. What do i mean by transpire? that is basically water loss through the foliage, Think of it like an athlete that sweats a lot during physical activity, They need to keep their fluids up a lot more then some body who is relaxing on the Couch. So in summer as it gets hotter the tree loses more water through it foliage so we need to replace that water.
Depending on how hot it gets in your region you may even need to water twice a day!
A good way to help battle this problem in summer is to Mist the foliage to help keep it cool. Some people may tell you that this will burn the leaves but if it is hot enough the water is not going to stay on the foliage long enough for the sun to use it as a magnifying glass and do any damage. On the other hand you may hear people saying to never mist a Bonsai Tree. The details they are leaving out is you should never mist in winter or late at night when there is no sun, The reason for this is that the water wont evaporate and will just sit on the foliage all night and this can cause fungus problems and attract unwanted pests. But you should understand why you mist now and have better knowledge on how to put it too use.
Wind is another factor that can cause water loss through transpiration in a tree, Next time you have a windy day take notice at how quickly your trees dry out, sometimes trees can dry out quicker on a windy day then a hot day. If you have noticed contestant wind through out the day its worth checking your trees and watering again if they need it, most of the broad leaf trees can signal low water by curling their foliage.
How Much Water Should i Use On My Bonsai Tree?
A General rule of thumb here is to do 1 sweep back and forth over the surface of the soil. So from left to right. Let the water soak in then repeat another 2x or until the water is coming out the bottom of the pot like a tap. If your water is not draining out the bottom of the pot like a tap then you may have soil that is a little too anaerobic meaning it holds too much water and not enough oxygen. What you want is a more aerobic soil that has an equal amount of water retention, oxygen and Nutrient retention. But that is a much larger discussion we will tackle later. But for now the general rule of thumb is if your tree is in a bonsai container it will need to drain well so a more coarse bonsai soil mix is very helpful. This will also help in situations where it rains for a week straight, Yes the Tree will be constantly watered but it will be draining just as fast pulling oxygen through the mix behind it. If you had soil that was anaerobic and it rained for a week you soil would be wet all the time leaving no oxygen in the mix.
Another problem that occurs with too much water in an anaerobic soil mix is Root Rot.
This is caused when there is water log in your pot and a bacteria infection forms and your roots start to rot, Once this happens the tree will no longer be able to take up water thus the tree will die once it runs out of its stored energy. This is similar to what happens when you use to much fertiliser, This is called reverse osmosis where you burn the root tips and they can no longer take up nutrients.
What Should I Use To Water My Bonsai Tree?
I do highly suggest getting your self a proper Bonsai Watering Nozzle. This is not just because we sell them in our store but because they are specially designed for the purpose of Watering Bonsai and they do have their use. A Special Bonsai Watering Nozzle has a softer flow head that still delivers a good amount of water too the plant but its not as powerful as a regular garden nozzle or even a watering can. If you use a regualr garden nozzle then there is a good chance you can wash everything you need off the top of your Bonsai Tree including the soil itself!. But you can also blast away your fertiliser, top dressings and figures. Thats why having a softer flowing head helps you water properly with ease.
I Hope this article has helped equip with with the knowledge of Why rather then How To and you can make some better choices on how you water your trees and how often. My best advice is study each species individually and adjust your soils and watering to suit each tree and adjust to each season.
Until next time Enjoy your Bonsai Journey!
If you want to further your education check out our Master Class Series Online Bonsai Course! https://www.bonsai-en.com.au/master-class-series