Best Type of Rocks for Bonsai Trees

In general, the best type of rock for a bonsai is pumice rock. Its ability to absorb water and retain water keeps the Bonsai healthy. It is also great for absorbing nutrients and allowing the roots of the bonsai to ramify well. Mixed with other soil components, it is a great rock for the bonsai tree.

Bonsai are known to symbolize peace and harmony. But shopping for the best type of rocks for your bonsai is anything but peaceful! Choosing the right kind of rocks/soil can be stressful but is necessary for your plant to develop healthily. 

Bonsai trees require care and nurturing. This includes care of the soil mixture and the rocks that go in them. Read on to learn more about the best rock for your bonsai and all of the details around picking the best combination of rocks for your bonsai’s soil.

What Is the Best Type of Rock for The Soil of A Bonsai?

The “soil” used for a bonsai tree is made of different substrates and this includes different types of rocks. The best type of rock for this soil is the pumice rock. The pumice rock is a volcanic rock. Here are some reasons why it is the best rock to have in your soil mixture.

  • It is fairly cheap compared to other substrates on the market
  • It is a lightweight rock which makes it easier to move the bonsai
  • It absorbs and retains water well, but does not absorb enough to make drainage a concern.
  • It is a very hard substance and will not break down like other substrates. Meaning it won’t need to be replaced every few years.

Pumice rock is a great rock for the bonsai tree for many reasons. When mixed with other substrates it creates a healthy soil for your bonsai to thrive in.

What Other Rocks Are Good for the Bonsai?

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Pumice rock isn’t the only rock that’s good to use in your bonsai’s soil mixture. The other rock you may want to include in your mix is lava rock. Lava rock is also a volcanic rock and is similar to pumice in many ways. It is a very popular choice when creating bonsai soil mix. Here are some attributes of lava rock.

  • It retains water well, but will not create drainage concerns.
  • It is a rough and jagged rock.
  • It is also a fairly cheap rock compared to other substrates.

Lava rock is a cheap option that retains water well and is also lightweight. It is another rock to consider adding to the mix of your bonsai’s soil.

Where Can You Find Rocks For Your Bonsai?

If you’re really lucky, you may live near a bonsai nursery! Then you will have access to premixed bonsai soil and don’t need to go looking for rocks and other substrates to make up the soil.

If you aren’t that lucky then no worries. There are plenty of online shops that sell both premade mixtures and individual substrates.

Just keep in mind, when shopping online for rocks or premixed soil, always remember to check the reviews and the estimated shipping time. You don’t want your bonsai to be without soil just because shipping took longer than expected.

What Qualities Should You Look for In a Mix of Substrates?

bonsai tree care

No matter what substrates you use in your soil mixture, when mixed together your soil should have these three qualities.

  • Aeration- Roots of a bonsai need oxygen to survive, and if there’s not good aeration If then it can be difficult for them to receive that oxygen. In addition, good aeration allows for good bacteria and mycorrhizae. 
  • Drainage- Nothing kills a bonsai faster than excess water at the bottom of the pot. When you water your bonsai, that water can remain in the soil for up to a week so good drainage is a necessity.
  • Water retention- Even though drainage is a necessity, so is retention. A bonsai is a plant after all! Water is necessary to supply moisture to the Bonsai, so you need to make sure your soil has a good level of water retention.

What Else Should Make Up My Soil Besides Rocks?

There are several other substrates that will make up your soil. Below is a chart with  different substrate options for your perfect soil concoction.

Akadamainorganic-A hard-baked Japanese clay.  It is a rather expensive substrate and is sometimes substituted with similar clays that are less expensive. -Akadama must be sifted before use.-This clay begins to break down after two years.
Organic potting compostorganicA catch-all for organic materials such as peat moss and retains a lot of  water and because of this shouldn’t be used as the only component in your soil mixture.
gravelinorganic-A material commonly used as a bottom layer in Bonsai pots.- This substrate helps with draining and aerating. -Most experts no longer use this substrate.

Does Every Bonsai Tree Need The Same Soil Mixture?

Your soil mixture will change greatly depending on the type of bonsai tree that you have. Although the substrates in the mix will most likely be the same, the amount of each substrate will vary depending on the type of tree you have, your climate, and the amount of time you are able to spend with your bonsai.

For deciduous trees, your soil mixture will mostly consist of Akadama. In fact, Akadama will make up half of the mixture.

Then pumice rock will make up one quarter and lava rock will make up the other quarter. For pine or coniferous trees, it’s more of an equal mixture. You will still use the same three substrates, but each one will make up about a third of the mixture.

Keep in mind that this soil formula will vary depending on your location and your circumstances. For example, if you live in a dry climate, you’ll want less grit or lava rock.

Or if you don’t think you’ll be checking in on your bonsai as often as recommended, then add more organic potting mix so you have better water retention.

How Do You Mix Your Rocks to Make Soil?

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You can create your own soil in a few easy steps. Here are the things you will need to do.

  • The first step (and an obvious step) is to buy your equipment. This includes your substrates and your soil sifter.
  • Next, you will need to decide on your ratio. Different types of bonsai’s need different ratios. So while some mixes may have 3 substrates and one-third of each substrate. Others might have large amounts of one substrate and smaller amounts of the others.
  • Once you’ve decided on your ratio, you can begin sifting! This is a very important step, so don’t overlook it.
  • After sifting is done, you can mix your substrates together to create your soil. 

Keep in mind that this is not a foolproof plan for soil creation. Each bonsai is different and each soil mix is different. Remember that you can always test out your soil mixture before plating your bonsai in it.

Bonsai are magnificent trees known for symbolizing peace and harmony. Shopping for the best type of rocks to make up their soil is an important part of properly caring for a bonsai.

Remember, pumice rocks are always a great rock for your bonsai’s soil mixture. And when mixed with other substrates they create a good base for your tree. Good luck and happy planting!


The best type of rock for a bonsai is pumice rock. This rock absorbs water and looks great. If you’re looking to buy a rock that isn’t too expensive and looks good, the pumice rock is definitely the way to go. If you’re interested in reading more about bonsai trees, check out this article here.

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Can Tulips Survive Snow

Can Tulips Survive Snow?

Yes, Tulips can Survive snow without a problem. Although, heavy snowfall could get too heavy on the tulips, which could crush them. However, generally speaking, snow shouldn’t be a problem for tulips.

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Can You Plant Store-Bought Tulips?

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