Watering A Bonsai Tree

Watering is by far the most important aspect of keeping a bonsai tree alive and healthy. Knowing when and how to water your bonsai tree can be tricky at the beginning as it’s so subjective, depending on a lot of different factors. This guide should help you understand everything you need to know to properly water your bonsai tree! 


How Often Does My Bonsai Need Watering?


How often your bonsai tree needs watering is a pretty subjective topic with a lot of variables. These variables include the species, the climate, location, time of year, the height of the tree, soil, moss and more, meaning giving a ‘one fits all’ style answer is impossible. The key is to check each tree individually at a regular interval to learn really what your tree needs to thrive, depending on the current conditions.


As your soil starts to get slightly dry, you need to water. To check this, I push my finger just less than an inch into the soil to see if it is moist or feels more dry. If it’s feeling more on the dry end of things, you need to water the tree. Having to check with your finger every-time really isn’t ideal but as you get more confidence and experience with that specific tree, you’ll begin to understand what to look for, so you’ll be able to gage it by eye instead.


Different bonsai soil mixtures will retain water differently, so if you’re looking to water your bonsai less, you could look at switching up the soil mixture to improve retention. This is what I would recommend if you have a job that means you’re working away quite a lot, so your trees won’t get in too much trouble in your absence.


What Time Of Day Should I Water?


It doesn’t really matter what time you water your bonsai tree during the day, as long as you’re watering it! People like to avoid watering their bonsais late into the day as the temperature is dropping into the night but if that’s when you check your tree, that’s when you should be watering it. I like to water mine during the first few hours of the morning, just because that’s what fits with my routine. Although I don’t ‘routinely’ water my trees, I do check them roughly at the same time everyday.


It’s pretty important to not have a strict routine when it comes to watering as during different times of the year, humidity and depending on the placement, the bonsai will need different amounts of water at different times. Different species of trees will also need different amounts of water as well, making a routine pretty redundant. It’s best to have a routine to check if the bonsai actually needs watering, then watering accordingly, rather than just watering anyway.


What Type Of Water Should I Use?


If you have any sort means of collecting rain water, that is by far the best water you can use to water your bonsai tree, due to it being natural and free of any chemicals that tap water will contain. For a lot of people, including myself, collecting rain water wasn’t really a feasible solution, so I use filtered tap water, which has never given me any problems at all. If you don’t have any means to filter the water, any water is still better than none in terms of keeping the bonsai alive, so use what you can. I would advise adding a small amount of nutrients to the water during growing season, especially if you aren’t able to use the rain water.


How To Water The Bonsai?


Once you’ve checked that the tree needs watering, fill up a small fine nose watering can or something similar, that won’t be too aggressive and wash your soil mix away. Evenly water the soil until water is pouring nicely through the drainage holes at the bottom of the pot. Leave the bonsai to drain for about 2-5 minutes, before repeating the process once more. This is the easiest and most effective way to water a bonsai tree. When doing this, if you desire, you can spray the foliage with a fine mist as well.


Do I Need To Water The Leaves Too? 


When I first got into bonsai, knowing absolutely nothing, this was something I was really curious about but I couldn’t find too much information online. In terms of keeping the bonsai alive, you don’t really need to water any of the foliage, just ensure that you are watering the tree properly down at the soil level.


I personally like to spray my bonsai leaves with a fine mist every day during the summer as in my experience it keeps the leaves healthier and looking a lot nicer during the hot months – whether that’s an actual fact or not I cannot say for sure. When misting the leaves I don’t use anything fancy, just a normal spray bottle that I had lying around from previous gardening projects. As per earlier, if you have rain water available then spraying a fine mist with that would be ideal, however filtered tap water will work just as well.


Using Moss To Retain Water


A lot of bonsai owners use moss on the soil to give the tree a certain aesthetic. However, beyond that, this can actually be extremely helpful in terms of watering your bonsai tree. The moss helps the soil to retain water slightly better, meaning there is less chance of the bonsai soil drying out so fast, especially during the heat. In terms of how much difference it actually makes, it’s hard to gage if it’s worth doing if you’re just looking at the moisture retention, however bonsai moss does look very nice so it’s still worth doing from that point of view.


Watering Doesn’t Seem To Be Helping My Bonsai?


Watering a bonsai is of course essential for its health but there are a few things you need to make sure you’ve done correctly in order to keep the tree healthy when watering.


Firstly, drainage holes. The bottom of your bonsai pot should have one or two holes that allow excess water to freely drain out of the pot when watering. This is absolutely essential to stop water causing the tree to develop root-rot, which will eventually kill the tree. It’s very rare to find a bonsai pot without drainage holes, but worth mentioning.


Secondly, the root mass being too tangled to properly absorb water. If you’ve had a bonsai in one pot for many years, it’s worth checking the root mass to see how tight the rootball is. If the rootball is too tight, the tree can have a hard time actually absorbing the water you’re providing, meaning it can actually still die with regular watering. If the rootball is too tight and compact, look at trimming some of the root mass away and repotting the bonsai into a larger pot.