Bonsai Soil

When it comes to bonsai supplies, bonsai soil is one of the most difficult to determine. There are many different formulas and no simple answers. Why special soil for bonsai?

Bonsai are essentially container plants we've made look like small trees.  Because we are asking these plants to live as long as they can in a pot, soil is a major consideration. 

Bonsai Soil Attributes

You can either mix your own or start by purchasing a basic bonsai soil mix.  Today, many hobbyists are using “soil-less mixes.” This just means they do not contain any earth or dirt.  (Never use dirt from your yard for any potted plants.) 

  • Fast Draining - One of the reasons watering bonsai is so difficult to learn, is the different types of soil bonsai are grown in. When watering, the water should run through quickly and come out of the holes in the bottom of the bonsai pot.
  • Water Retention - No matter the soil content, some moisture must be retained. Some components hold more water than others.
  • Aeration –Space between particles is important. This does not mean “air pockets,” which we always avoid.  It means the mix should not be so fine or wet, that it becomes compacted.

Soil Components

Container gardeners and plant nurseries grow in a vast number of soil mixes. Many use a very heavy, wet type of soil to prevent drying out so quickly. That does not mean the plant prefers this type of soil, only that it will survive in it for starter growing purposes. If you purchase a pre-bonsai plant in one of these heavy soils, eventually you will need to remove it.
Once we create our bonsai and they are ready for bonsai pots, very heavy, extra fine and/or muddy soils should be eliminated. Depending upon the species of plant, it may be done gradually or in some cases it can be done all at once. Always consider the time of year!
Remember, when it comes to soil, what someone else temporarily ‘gets away with,’ may prove to be a killer in the long run.

If you decide to make your own bonsai soil, remember all components should be free of dust and be similar in size. This can be resolved with sifting and rinsing. (Dust and very small particles can clog the drainage.)

Try using one of each - organic and inorganic. 

Discover which works best for you and your bonsai. Never repot all your bonsai in a recommended mix, without testing it first.


Some people use peat moss to add acidity for certain plants. However, it retains a lot of water and should be used sparingly.

"Potting soil" from garden centers is a last resort for organics and should only be used with the addition of an inorganic aggregate.  If you choose to purchase potting soil, do not buy the cheapest!  It will most likely be the wettest and heaviest, which is what you do not want!


You will hear about many seemingly odd materials to add to your mix including ‘chick grit’ (a crushed granite available in farm feed stores) and 'kitty litter' a type of calcined clay, as well as imported akadama clay.

Used properly they all work. Lava rock and pumice are other additions used with good results. Overall, a good mix looks like small gravel!

  When you purchase a bonsai, the top soil you see may or may not be what it's growing in.  Take a chopstick and dig down a little to determine the actual soil.  If any gravel is glued on, remove it immediately for better drainage.   

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