A juniper bonsai tree is a beautiful miniature tree that can thrive for many years with proper care. One of the most important factors in caring for a juniper bonsai is using the right kind of soil. The soil provides essential nutrients, drainage, and moisture retention for the health of the roots and the entire tree. In this article, we will look at the ideal properties of soil for juniper bonsais and the best ingredients to use.
Why Soil Matters for Juniper Bonsai
The soil is the foundation that supports the growth of any plant, and juniper bonsai trees have specific soil requirements. Junipers prefer soil that drains well yet retains some moisture. The soil must also have the proper pH balance and nutrients for the juniper. Using the wrong type of soil can lead to poor health and stunted growth. The ideal soil will have these key features:
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Good drainage and aeration – Excess water must be able to drain away easily so the roots don’t get waterlogged. The soil also needs air pockets for oxygenation.
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Moderate moisture retention – The soil should be able to hold enough water between waterings without drying out completely
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Slightly acidic pH – Junipers thrive best in soil with a pH between 55 to 65.
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Low in nutrients – Too many nutrients like nitrogen can burn the sensitive juniper roots.
Recommended Ingredients for Juniper Bonsai Soil
To create soil with those ideal properties, certain components are better suited than others. Here are some of the best ingredients to use:
Akadama
Akadama is a clay granule made specifically for bonsai soil mixes. It offers good water retention while still allowing drainage and air circulation. Akadama maintains a stable pH in the optimal range for junipers. It is often used as the main component of juniper soil.
Pumice
Pumice is a porous volcanic rock that improves aeration and drainage. The many tiny air pockets allow oxygen to reach the roots. Pumice also helps keep the soil loose.
Lava Rock
Like pumice, lava rock contributes excellent drainage and air circulation. Lava rock creates spaces in the soil for unrestricted root growth.
Peat Moss
Peat moss can help increase moisture retention in the soil. It also contributes to a slightly acidic pH preferred by junipers. When mixed appropriately with drainage components, peat moss offers beneficial qualities.
Pine Bark
Pine bark assists with drainage while providing some moisture retention. It breaks down slowly to give a steady supply of nutrients. When used sparingly, pine bark can complement the other inorganic ingredients.
Making Your Own Juniper Soil Mix
With the right components, you can easily create a custom soil blend for your juniper bonsai. Consider these simple recipes:
- 2 parts akadama, 1 part pumice, 1 part lava rock
- 2 parts pumice, 2 parts lava rock, 1 part peat moss
- 2 parts akadama, 1 part pine bark, 1 part pumice
Always use a coarse gritty texture for optimal drainage. Combine ingredients in ratios that balance moisture retention with ample aeration. Test the drainage of your mix by watering thoroughly and checking that excess flows out the bottom.
Buying Pre-Made Bonsai Soil
For convenience, you can purchase pre-made bonsai soil mixes specifically for conifers like junipers. Look for these traits when selecting a commercial blend:
- Mainly inorganic materials like akadama, pumice, and lava rock
- Little to no fine particles that can compact
- Lack of added nutrients
- Low or neutral pH rating
- Components like peat moss to retain some moisture
Reputable bonsai soil brands will offer blends already suited for juniper health.
Soil Types to Avoid for Juniper Bonsai
On the other hand, some soil types available at garden centers can be unsuitable for junipers:
- Regular potting soil often stays too wet and contains excess nutrients
- Succulent or cactus mixes drain too quickly
- Pure compost or coconut coir retains too much moisture
- Soils with added chemical fertilizers can burn roots
Always check the ingredients and descriptions before using a generic potting mix.
Testing and Adjusting the Soil
Once you have obtained a suitable juniper bonsai soil, verify that conditions are right:
- Use a pH meter to test for a slightly acidic level around 6.0.
- Check drainage by watering thoroughly and watching excess water flow out the bottom.
- Feel for a loose, crumbly texture without thick mud or dust.
Adjust as needed by adding amendments like lime to raise pH or peat moss to improve moisture retention.
Refreshing the Soil Over Time
Each time you repot the juniper, replace at least 30% of the old soil with fresh mix. Discard any depleted or compacted portions. Introducing new soil components replenishes nutrients and minimizes diseases.
With the proper soil that meets their requirements, juniper bonsai trees will thrive with vibrant green foliage and shapely form. Carefully follow recommendations for creating the ideal soil environment. A quality growing medium lays the foundation for many years of bonsai enjoyment.
Organic or Inorganic Soils
Soil mixes are described as being either organic or inorganic. Dead plant matters such as peat, leaf-litter, or bark are described as being organic soil components. The potential problem with organic soil components is that organic matter breaks down and reduces drainage over time. Some organic components deteriorate at varying speeds, so itâs hard to say how quickly organic soil becomes harmful. If youâre adamant about using an organic soil mix, we recommend choosing a mixture that uses pine bark. Most potting composts absorb water very poorly once they are completely dry. This is one of the biggest problems for cheap indoor Bonsai trees purchased at garden centers. Youâd think you watered the tree but the water runs past the soil into the bottom of the pot!
Inorganic soil components contain little to no organic matter such as volcanic lava, calcite, and baked/fired clays. They absorb fewer nutrients and water than organic soils but are great for drainage and aeration. The limited absorption capacity also gives us more control over the amount of fertilizer in the soil.
A particle-based, well-structured, inorganic soil allows water to drain quickly and fresh air to continually enter the soil. A compacted organic soil that lacks structure also lacks aeration and drainage which deteriorates the overall health of your tree, and without swift action, will eventually cause root rot and kill your bonsai.
The most common components for Bonsai soil mixtures are Akadama, Pumice, Lava rock, organic potting compost, and fine gravel also known as grit.
From left to right; organic potting compost, Akadama, Pumice, and lava rock.
Akadama is hard-baked Japanese clay specifically produced for Bonsai purposes and available on all online Bonsai shops. If you purchase Akadama, keep in mind that It needs to be sifted before use, and after about two years it does start to break down which reduces aeration. This means that regular repotting is required, or that Akadama should be used in a mix with well-draining soil components. Akadama is rather expensive and is therefore sometimes substituted with similar fired/baked clays that are easily available at any garden center. Even cat-litter can be used as a substitute, check our Bonsai forum to see which brands are available in your country.
Pumice is a soft volcanic rock, which can absorb water and nutrients quite well. When used in a Bonsai soil mix it helps to retain water and allows the roots to ramify very well.
Lava rock also helps retain water and create a good structure when part of a Bonsai substrate. Roots cant grow into the Lava rock.
Organic potting compost is made up of peat moss, perlite, and sand. On its own, it retains too much water and doesnt allow for proper aeration and drainage, but as part of a soil mixture, it can work very well.
Fine gravel / grit helps to create a well-draining and aerated Bonsai soil. It is also used as a bottom layer in Bonsai pots to enhance drainage. Most experts have stopped using it, as they tend to stick with a mixture of Akadama, Pumice, and Lava rock.
Recommended Bonsai soil mixtures
Different tree-species demand different soil-mixtures, so make sure to check our Tree species guide to find the optimum mixture for your specific trees. However, we can describe two main mixtures we use for either deciduous or coniferous trees. Both mixtures consist of Akadama for water retention, Pumice for good substrate structure, and Lava rock for aeration and drainage.
Note that both mixtures can, and should, be adapted to your circumstances and/or location. If you know you wonât have enough time to check on your trees twice a day, then add more Akadama or organic potting compost to your mix for increased water retention. If you live somewhere with a wet climate, add more lava rock or grit to enhance the draining qualities of your mixture.
- 50% Akadama
- 25% Pumice
- 25% Lava rock
Greenwood Bonsai – Bonsai Compost Alternatives
FAQ
What’s the best soil for juniper bonsai?
Juniper Bonsai Tree does best in well-draining soil. A good soil will contain lots of organic matter such as coco coir as well as perlite or vermiculite to help with drainage. Adding a handful of perlite to regular store-bought potting soil should do the trick!
What kind of soil is best for juniper?
Junipers prefer open, sunny locations in well-drained soils. They will tolerate a wide range of pH levels. They are very tolerant of dry, clay soils and many varieties will grow in sand. Some types, such as Sargent juniper and Shore juniper have shown good salt tolerance.
What’s the best potting soil for a bonsai tree?
I usually use 30% – 50% akadama mixes (the remainder can be pumice and/or lava rock) for tropical bonsai. If a tree stays too wet I’ll use less akadama, and if I want the soil to retain more moisture, I’ll use more akadama.
What is the best soil for bonsai pines?
Bonsai Growing
Our Kiryuzuna bonsai soil is a great choice for Pines, Junipers and other conifer species. It has a similar structure to Akadama but is a little more dense and hard and should last a long time before breaking down in the pot. Mix with other mediums for extra drainage or use neat.