A Guide to (or opinion on) Bonsai soils and mixes

There are probably as many different Bonsai soil mixes as there are Bonsai enthusiasts and certain mixes work better for some people than they do others, due to what part of the country or even the world they live in, their watering regimes and the species of Bonsai.

So what are we looking for in a Bonsai mix? Good water and nutrient retention, yet free draining, so that the roots of the Bonsai don't get waterlogged and get enough air, as well as media that will release water and nutrients at different rates, so that the soil does not dry out too quickly.

The basics which we stock and use:

Whilst some Bonsai enthusiast do, and this comment is subject to where in the world you live, in the UK I would not use any of the following products on their own.

Akadama - Probably the most well known Bonsai soil component. Only available from Japan, which makes it fairly expensive. It is an inert and inorganic hard clay media which has good moisture and nutrient retention properties. It is available in either standard grade (around 2mm to 5mm) or shohin grade (1mm to 2mm). One of its advantages is that the fine roots of plants will grow in to this media and split, which helps to produce more fibrous roots and according to many, better ramification of your Bonsai. One down side with Akadama is that it can break down over a few years, due to freezing and thawing, however this can be slowed with the addition of harder media to a mix. Is it worth the extra expense over other so called alternative media? I think so.

Pumice - A fairly well known volcanic media, our pumice is imported from Japan and is graded 2mm to 4mm, not to be confused with some other pumice media on the market, graded 0mm to 8mm. Pumice is porous, inorganic and inert with a neutral PH and has good moisture and nutrient retention properties. Like Akadama, the fine roots of plants will grow in to this media and split. Pumice will release water and nutrients at a different rate to Akadama and when mixed with Akadama, will help to slow down the breakdown of Akadama due to freezing and thawing. It is a fairly hard media which resists break down due to freezing and thawing. One down side is that it is fairly light in colour and some people do not like it due to this, but that is purely aesthetics. See LavaLec^®La below.

Lava - Another fairly well known volcanic media, our Lava is graded 2mm to 6mm, although it does contain some dust and can contain the odd larger particle, although the dust does wash through when first watered. Like Pumice, Lava is porous, inorganic and inert with a neutral PH and has good moisture and nutrient retention properties and like Akadama and Pumice, the fine roots of plants will grow in to this media and split. Lava will release water and nutrients at a different rate to both Akadama and Pumice and when mixed with Akadama, will help to slow down the breakdown of Akadama due to freezing and thawing. It is a very hard media which will not break down due to freezing and thawing. The properties and advantages of Lava and Pumice are quite similar, with Pumice having slightly better water retention / release properties than Lava. See LavaLec^®La below.

LavaLec^®La - A fairly new media and is graded 2mm to 4mm. Like Pumice and Lava, LavaLec^®La is porous, inorganic and inert with a neutral PH and has good moisture and nutrient retention properties and like Pumice and Lava, the fine roots of plants will grow in to this media and split. LavaLec^®La will release water and nutrients at a different rate to Akadama and Pumice and when mixed with Akadama, will help to slow down the breakdown of Akadama due to freezing and thawing. It is a fairly hard media which will resist break down due to freezing and thawing. The water retention / release properties of LavaLec^®La are quite similar to Lava and therefore I believe that it is a good alternative and cheaper.

Kiryu - Or to use its full name, Kiryuzuna is a lesser known Bonsai soil component. Only available from Japan, which makes it fairly expensive. Kiryu is porous, inorganic and inert with a neutral PH and has good moisture and nutrient retention properties and like the previous media, the fine roots of plants will grow in to this media and split. Kiryu is great for pines, which grow really well when this is used in a mix. In some parts of the world, Bonsai enthusiasts use it on its own for pines, however in the UK I believe that you need to mix it with other media, particularly Akadama, as I feel that Kiryu dries out too quickly, even for pines, when it is used on its own.

Kanuma - Used exclusively for Azalea and other acid loving plants. Only available from Japan, which makes it fairly expensive. Kanuma is lightweight, porous, inorganic and inert with an acidic PH (5 to 6) and has good moisture and nutrient retention properties and like the previous media, the fine roots of plants will grow in to this media and split. Kanuma can breakdown due to freezing and thawing, but it is used on its own, without any other media added. If you grow Azalea then use it, as it is the best and there are no alternatives.

Fine Chipped Bark - I like to some organic media to my mixes, as it helps with good bacteria and Mycorrhizal fungi (beneficial fungi growing in association with plant roots and exist by taking sugars from plants 'in exchange' for moisture and nutrients gathered from the soil by the fungal strands. The mycorrhizas greatly increase the absorptive area of a plant, acting as extensions to the root system). Our Fine Chipped Bark comes from fir and pine trees and is largely graded to 3mm to 6mm, although does contain some larger and finer particles. It has the greatest water retention of all the media which we sell, however it also releases water quicker than all. It is fairly acidic with a PH of 4 to 5 and whilst some will argue that it shouldn't be used in mixes for lime loving plants, but I have never had any problems with it. I prefer to use Fine Chipped Bark over other alternatives, such as peat based compost, as it keeps the soil mix more open.

Moler - Also known as Terramol, Danish Pink, Biozorb and many other names, it is a hard baked clay media graded to 3mm to 5mm. Moler is an inert and inorganic hard baked clay media which has good moisture and nutrient retention properties. It has a ph of around 5.5, so is fairly acidic and some will say that it should not be used in mixes for lime loving plants. Its moisture and nutrient retention and release properties are better than Akadama, however the pores are too small to let roots in. One advantage of Moler is that it is hard and does not break down like Akadama, due to freezing and thawing. When mixed with other hard media, some will argue that Molar is better than Akadama, because you can re-use your soil after repotting. Is it an alternative to Akadama? I don't think so. Whilst it has the highest water retention of all the above inorganic media, due to the fact that roots cannot penetrate the granules, I think not. I would still go for Akadama any day and not recycle my soil. Some customers mix it with Akadama to make it go further, hence why I stock it.

Sphagnum Moss -  Used by many shredded in mixes, Sphagnum Moss is known to help root production on newly repotted Bonsai and particularly beneficial for sickly trees.

Bamboo Charcoal - Charcoal increases the soil's ability to hold onto plant nutrients and beneficial soil microbes by slowing or reducing the leaching of nutrients by rain or watering and helps to reduce the toxins and impurities in water. Its use with Bonsai soil mixes is fairly new in the UK, but is producing good results. Our Bamboo Charcoal is imported from Japan and whilst other horticultural charcoal products are available, I have found that Bamboo Charcoal is better graded with fewer fine and larger particles.

Loam based compost - Whilst we do not sell this, as it is readily available from most garden centres, I do use it in one of our mixes, blended with other media. It is particularly useful for Indoor Bonsai, as it is very slow to dry out compare to other media. Again when mixed with other media, it is suitable for broad leaf UK native trees. It should not be used on its own for Bonsai.

Kyodama - This is the trade name for a man made porous ceramic based media. I stock it as LavaLec^®Za. Its properties are very similar to Lava and LavaLec^®La and it is popular with a number of customers, but is a lot more expensive than LavaLec^®La.

The basics which we do not stock or use:

Sand, granite grit or fine aquatic pebbles - These have little or no water or nutrient retention properties. The only advantage is that these types of media may keep the soil open, however water will sit on the outside of these due to tension and arguably this may contribute to water logging. The fine roots of plants will not grow in to this media. Personally I wouldn't touch these with a barge pole, as far as Bonsai soil mixes are concerned.

Zeolite - A fairly new product on the Bonsai scene, this media has been widely used in water treatment for many years. Zeolite provides a source of slowly released potassium and if previously loaded with ammonium, zeolite can serve a similar function in the slow release of nitrogen. However from memory, Zeolite can also lock in nitrogen, which can only be released by flushing with saline solutions. I think that I would rather provide potassium via a fertiliser and I don't see the point of using a product which locks in one of the ingredients of my fertiliser. I'll give it a miss I think.

Perlite - Similar to Pumice, but much lighter in both weight and colour and usually very cheap. Like sand, granite grit or fine aquatic pebbles the only advantage with Perlite is that it may keep the soil open, however whilst the surface area of perlite is much larger than Sand, granite grit or fine aquatic pebbles, water will sit on the outside of media and the fine roots of plants will not grow in to it. Why use it when you can use LavaLec™La, Pumice or Lava, which are much better media for your Bonsai and also look better than all those white specks in the soil.

Peat based compost - A cheap media readily available from most garden centres. I would certainly not use this media on its own for Bonsai and whilst some may argue, I would not use it as part of a Bonsai mix.

Garden compost - A lot of people make their own compost from grass cuttings and food waste, etc. This is not something that I would recommend adding to your Bonsai mix, as it can contain microbes and other elements that would harm your Bonsai.

If you find the whole thing too complicated or would prefer not to make up your own mixes then take a look at our pre-mixed soils:

British Bonsai Soil Basic and Indoor Mix - This soil is specially mixed at the Nursery and uses top quality ingredients. LavaLec^®La, Pine Bark and Loam, mixed at just the right quantities for good moisture retention yet sill fairly free draining. Suitable for most UK native deciduous Bonsai and ideal for indoor Bonsai that require better moisture retention, as well as many other species.

British Bonsai Soil Premium Mix - This soil is specially mixed at the Nursery and uses top quality ingredients. Akadama, LavaLec^®La and Pine Bark, mixed at just the right quantities for good moisture retention yet still free draining. Ideal for all deciduous Bonsai and some evergreen Bonsai such as Junipers and Yews. Due to the composition of this mix, you are more likely to end up with a finer root mass over the Basic Mix, but you will need to water more frequently. Not suitable for indoor Bonsai.

British Bonsai Soil Premium Plus Mix - This soil is specially mixed at the Nursery specifically for Pines and uses top quality ingredients. Kiryu, Akadama, LavaLec^®La, Pumice and Pine Bark, mixed at just the right quantities for good moisture retention yet still free draining. Add a hand full of Charcoal and finely chopped Sphagnum Moss for every 2 ltrs of the mix for the best results. Not suitable for indoor Bonsai.

British Bonsai Soil Premium Mix Shohin - This soil is specially mixed at the Nursery and uses top quality ingredients. Shohin Akadama, LavaLec^®La, finely chopped bark and fine chopped sphagnum moss, mixed at just the right quantities for good moisture retention yet still free draining. Ideal for all deciduous Bonsai and some evergreen Bonsai such as Junipers and Yews. Due to the composition of this mix, you are more likely to end up with a finer root mass over the Basic Mix, but you will need to water more frequently. Not suitable for indoor Bonsai.

British Bonsai Soil Premium Plus Mix Shohin - This soil is specially mixed at the Nursery specifically for Pines and uses top quality ingredients. Shohin Kiryu, Shohin Akadama, LavaLec^®La, finely chopped bark and fine chopped sphagnum moss, mixed at just the right quantities for good moisture retention yet still free draining. Not suitable for indoor Bonsai.

Please note that some of mixes may have quantities of dust in them. We would recommend that you do not sieve these out and you wash this through well after repotting.