The Truth About Moss for Bonsai: Good, Bad, or Both?

The Truth About Moss for Bonsai: Good, Bad, or Both?

Moss For Bonsai, Good or Bad?

This is an argument I see all too often with people in Bonsai on whether putting moss on your bonsai is good or bad for it, and honestly in the argument both people are correct. It is both good and bad but understanding the use of moss on Bonsai can hopefully shed some light on this topic. In todays article we are going to look at the good the bad and the ugly of moss on bonsai to give you a better understanding of if this technique is for your trees or not.

Lets Start With The Good Uses For Moss On Bonsai

Water Retention : In arid areas trees will need all the help they can get when it comes to hanging on to moisture, but this isn’t true across the board. Most professionals and enthusiasts use a very open mix of Akadama, Pumice and Lava Rock or something similar. The soils drain exceptionally well but are also more aerated meaning they can dry quicker. So in this case having a layer of moss on the surface actually helps slow the evaporation, the root system will still take up the same amount of moisture so keeping an eye on your watering will still be necessary, but having a blanket of moss on the surface can help slow down the un necessary loss of moisture due to wind and heat.
Extra Root Growth : Roots don’t like over exposure to air and light which is in abundance at the surface layer of your mix, we do try to reduce this with a finer particle layer on top but its not a magic bullet. Having a layer of moss on the surface both reduces the amount of air and light at the surface meaning roots will be more likely to grow all the way up to the top of the soil surface and occupy more soil mass within the pot. When we have a tree in a small pot we want to try and get as much root mass as possible inside the pot so the tree has a better chance of fighting of pests and disease, can re hydrate itself more efficiently and can take up nutrients more efficiently. Most pots without moss wont have the top inch or so of the pot occupied leaving much needed real estate vacant.
Water Filtration : Moss is good at filtering harmful chemicals and minerals out of your town water. Minerals aren’t bad for a tree in small amounts but we all know the towns go overboard on what’s in the water to protect the pipes underground, You only have to smell the water and taste it to know its very mineral rich. They also put chlorine in the water which can be evaporated over night if you have a holding tank. But moss is a good thing to have to help filter out some of the hardness of your water.
Aesthetics : This is the main reason most people moss the surface of their pot. It just looks good, especially if you can grow moss properly by propagating it your self and growing it on the soil surface. It can look soft and vibrant and makes your tree look like its in a landscape. Some people only moss their trees for shows just to get this aesthetic appeal and then later remove the moss to avoid some of the pit falls it can have which we will talk about now.

The Bad Side Of Moss For Bonsai

Too Much Water Retention : We just said this was a good thing right? Well not in the case of those that use organic soils in their bonsai pot. Organic soils hold a high amount of moisture in a bonsai pot and have a hard time draining to begin with, so put a layer of moss over the top that will help trap in that moisture and you could be in for disaster. So if your still using organic potting mix I would avoid moss for your trees.
Moss On The Trunk : Moss can sometimes get out of control and begin to climb the trunk, this is not healthy for your tree as the amount of moisture held by moss directly on the trunks surface can start to rot the base of the trunk away if not taken care of. This is easy to avoid though with regular checks while you water your trees and regular maintenance of your moss.
Covering Up The Nebari: When you first apply moss you can place it in between the nebari and around it but eventually like we mentioned above it can start to take over and hide all the hard work you have done to build a nice root structure. Once again though this is easy to take care of with some observation and regular maintenance.
Over Watering Caused By Moss : This is probably the biggest problem, When people apply moss to their tree and they are still relatively new to the hobby they can accidentally over water the tree because the moss begins to look dry. We call this watering for the moss and not for the tree. Moss will always dry out faster then the tree will so its important to keep in mind if your moss begins to dry and you want to bring it back then you need to mist the moss not water the tree. Always check the actual soil of the tree to gauge if the tree needs water or not, don’t ever gauge off the moisture levels of the moss.

So what about the Ugly Side Of Moss For Bonsai?

Well this comes down to a few things really, What moss is used, how its placed, and how its grown. So lets take a look at these things.
What Moss Is Used : Its important when collecting a moss for your tree that you get one that is as close to your environment as possible and is used to the same light and weather conditions that your tree is used to. For example if you collect some moss from a forest floor and apply it to your juniper that sits out in the sun all day long you will struggle to keep that moss looking good as its used to a lot of shade and moisture. In this case you would want to find some moss that has high exposure to sunlight and limited moisture. There are also some moss species that just look nasty so try to pick moss that is clean and vibrant looking.
How Its Grown : This can make or break your moss, most people go out and collect moss then place it directly on the surface of the pot. This is what I would call the wrong way. This can be ok though if you have been growing the moss in a tray and are just placing it on the tree for a weekend show. But if your planning on having your moss live with your tree full time the best way to do it would be to propagate the moss directly on the surface of your soil.
This is done by collecting moss and letting it completely dry out. You’ll then want to grind it down into small particles and use a sieve to separate the moss spores from the fine dirt with small 1mm screen. You will then want to grind up some sphagnum moss into smaller particles and mix the 2 50:50 and place it on the surface of your tree. The moss will actually grow using the surface of the soil as its base medium and the moss will look the best it can. This does take a few months for the moss to actually grow though so it’s a game of patience. But youll find your moss stays hydrated and looks nicer for longer periods of time like this.
How Its Placed : How you either grow or place your moss on the surface can be the difference between a nicely mossed surface and a car wreck. There are some people that go right into detail and use different shades of moss to create depth in the design of the composition. But be carful because if you get that wrong the pendulum can swing in the other direction. For most people evenly placed moss without too many undulations is the best option until you can start getting a little more creative with your designs. Just remember leave the base of the tree exposed and keep the moss off the trunk.


So there you have it, The good bad and ugly of moss and hopefully now you can use this information to make informed decisions on whether moss is good for your situation or not. As mentioned its hard to take peoples answers on the internet as fact as there is a lot of context missing from their arguments so getting a blanket answer of if moss is good for bonsai or not needs to be taken with a grain of salt, or you can link them to this article so they can help to educate better.

1 comment

Other bad things about moss.
Eats/roots bark causing reverse taper.
Slows gas exchange.
In the northwest North America it is a pain. So prolific.


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Author : Joshua Hooson

Joshua Hooson is an author and enthusiast of the art of bonsai. He has built his knowledge and understanding of bonsai through a combination of self-experience, lessons learned through hands-on practice, and extensive research. His articles reflect his passion for the subject and offer insights gained through his own personal journey in the world of bonsai. All the information provided in his works is a result of his own experiences and the knowledge he has gained through his studies. He is dedicated to sharing his love of bonsai and helping others grow in their understanding and appreciation of this ancient and beautiful art form.

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