Best soil?

[Ruddigger]

If you’re going to get serious with bonsai get used to mixing your own soils. I’d go with a 1:1:1 like @yashu said, or a 1:1 akadama/lava.

 

[yashu]

All decent substrate for bonsai has water retentive properties and junipers very much like water, just not like that of bald cypress. If you included only non-water retaining substrates in your mix, you'd be watering like a mad man. But junipers adaptable, to a degree.

The size of the substrate is arguably just as much an issue as the substate itself. The larger the particle size equals less water-retention capacity and more aeration capacity.

Based off this study:

Their findings:
Organic Substrates

1. Coconut Coir: 129g @ 14.57% loss
2. Compost: 26g @ 31.58% loss
3. Pine Bark: 22g @ 33.33% loss
4. Commercial Peat Moss: 6g @ 40% loss

Inorganic Substrates

1. Diatomaceous Earth: 37g @ 30.19% loss
2. Akadama: 22g @ 26.67% loss
3. Kanuma Pumice: 22g @ 29.03% loss
4. LECA (Turface): 30g @ 36.17% loss
5. Vermiculite: 28g @ 41.67% loss
6. Perlite: 14g @ 36.36% loss
7. Sand: 12g @ 67.56% loss
8. Lava Rock (Scoria): 4g @ 76.47% loss
9. Expanded Shale: 2g @ 84.62% loss
10. Granite Chips: 1g @ 94.44% loss

24-hour Retention Rankings

Organic Substrates:

1. Coconut Coir
2. Compost
3. Pine Bark
4. Commercial Peat Moss

Inorganic Substrates:

1. Diatomaceous Earth
2. Akadama
3. Kanuma Pumice
4. LECA (Turface)
5. Vermiculite
6. Perlite
7. Sand
8. Lava Rock (Scoria)
9. Expanded Shale
10. Granite Chips

Akadama, lava rock, and pumice (2:1:1 ratio) is commonly suggested as the 'gold standard' for juniper and other bonsai.

For the sake of this study, Akadama is one of the most water retentive of the substrates next to Napa 8822 (diatomaceous earth) -- and so is pumice. With a 2:1:1 of akadama, lava rock, and pumice, with water retention at ~ 61% water retention with ~17g weight.

Another, popular, cheap method is sifting Napa 8822 or Floor Dry, mixed with half perlite and 10 percent pine bark. 1:1:0.10 ratio, equaling ~ 67% water retention with ~ 25g weight.

The amount of water retained by both are acceptable. So long as it is a fast-draining substrate that retains water for the roots to stay moist and to allow air in for roots to breathe, it's really the same. The only thing that would change is frequency in watering and esthetics.

Though, the confounding variable in this study is the particle sizes not being measured, only its weight was. Common substrate mixes are not mixed together at different ratios and then measured. Also, the measurements are taken in only one environment and for only one day out of the year -- not to mention it didn't show any bonsai being grown successfully in the substrates.

But if the particle size is increased, the water retention and air capacity are then altered. Fine particles can clog the soil, drowning or suffocating roots, while too large particles might lead to insufficient water retention and roots drying out. A balance between water retention and aeration is essential and an even finer tweaking can help with watering frequency.

Roots need to breathe, they need moisture, and the soil needs to be fast draining for both those things. There are too many mixes to go over, but pine bark and Napa 8822 don't retain too much water for a juniper to grow in. Too many people have been successful with it and not by chance. Perhaps the ratio or particle sizes are to blame if someone has had a bad experience with this mix with their junipers -- among many other confounding variables, e.g. tree health/genetics, environmental stimuli, fertilizers frequency and quantities, watering habits, human error and neglect.

Akadama, lava, and pumice has been used for some time -- tried and true -- yet more expensive.

As requested, a cost-effective alternative, a mix of perlite, pine bark, and calcined clay (Napa 8822) can be used to great effect -- also tried and true, as many have resorted to this mix over recent years.

In the end, experiment for yourself and make adjustments as needed.

They have 'soil wars' here. It's usually a hot topic.

This is probably not helpful to a beginner asking a simple question for which there is a very simple answer. Everyone who’s been doing this for a while knows this can be as complicated as you want it to be.

 

[Jrmcmich]

Seems like for pre bonsai to just grow out a perlite and coco coir mix seems fairly popular and can always adjust perlite % based on watering frequency your able to do. Fairly cheap as well. I used bonsai soil for pretty much everything this past spring but can see that will be costly amd will probably try to switch to this type mix just growing out my smaller trees. I’m not stating this is best soil just a fairly easy cost effective solution.

I will probably eventually mix my own as well but not sure ratio I would use of components but from earlier posts above looks like some good ideals for both deciduous and conifers.

 

[99 Mile Creek]

This is probably not helpful to a beginner asking a simple question for which there is a very simple answer. Everyone who’s been doing this for a while knows this can be as complicated as you want it to be.

That response wasn't aimed at the OP, rather the statement: "Be careful with 8822 in juniper or pine mix. It is water retentive - not liked by the species." It's simply not accurate.

And for the sake of beginners who take up the hobby, feet running, it's not really too much for a thread entitled: Best Soil? on Bonsai Nut.

As @Ruddigger said, if you plan to get serious, simply learn to mix your own -- if not, buy a premix. If it's the former(edit), it's not quite as simple an answer as it might appear.

 

[Orion_metalhead]

There is no tractor suppl

That response wasn't aimed at the OP, rather the statement: "Be careful with 8822 in juniper or pine mix. It is water retentive - not liked by the species." It's simply not accurate.

Growing juniper and pine in 8822 (which I have done) is not advised. When I started, I grew everything in 8822... most of my pine seedlings kicked the bucket only a handful survived. All died from root related issues.

I now use only as one part of an ingredient.

The real key is that anything can work if you water to the tree's needs. My current conifer mix:

1:1 Sifted Perlite and Sifted Saf-t-sorb or 8822 = (component 1)
then
1: 1/2 : 1/2 Component 1 to Crushed pine bark to pea gravel.

This for NJ 7b watering 1 time a day in morning.

For deciduous:

1:1:1/2 Component 1, Greenwaste compost, crushed pine bark.

Adjustments made for things like pot/container size, developmental stage etc. I also do use akadama as well for more advanced trees in place of 8822 or turface or as an added ingredient.

 

[99 Mile Creek]

Growing juniper and pine in 8822 (which I have done) is not advised. When I started, I grew everything in 8822... most of my pine seedlings kicked the bucket only a handful survived. All died from root related issues.

I now use only as one part of an ingredient.

My current conifer mix:

1:1 Sifted Perlite and Sifted Saf-t-sorb or 8822 = (component 1)
then
1: 1/2 : 1/2 Component 1 to Crushed pine bark to pea gravel.

This for NJ 7b watering 1 time a day in morning.

For deciduous:

1:1:1/2 Component 1, Greenwaste compost, crushed pine bark.

Adjustments made for things like pot/container size, developmental stage etc. I also do use akadama as well for more advanced trees in place of 8822 or turface or as an added ingredient.

That's insightful. It's always interesting seeing different and refined approaches based on experience.

The real key is that anything can work if you water to the tree's needs.

You hit the nail on the head. Great point.

 

[Paradox]

If you’re going to get serious with bonsai get used to mixing your own soils. I’d go with a 1:1:1 like @yashu said, or a 1:1 akadama/lava.

I'd say 1:2 akadama to lava or pumice so it's the same ratio of akadama to whatever else as 1:1:1.
1:1 akadama to lava or pumice fine for deciduous

Agree though, soil can be a very complicated and contentious issue.

I found when I first started, I was a heavy waterer so the open mix for me is best because it's impossible to overwater. Plus since I water every day with an automatic system or if we get a week of rain in the spring, I don't worry about things being too wet.

 

[Maiden69]

Seems like for pre bonsai to just grow out a perlite and coco coir mix seems fairly popular

It all depends, it is a good mix for propagation and for small (shohin) and smaller pre-bonsai, anything bigger (that will shoot a leader a few feet long) and you will have an issue with the wind moving the tree in the soil until its root ball becomes intact. I am using inorganic soil for my pre-bonsai, Monto Clay, Bonsai Block from Bonsai Jack and pumice. The advantage is that once I take the tree out of it I can rinse it, let it dry in the sun and re-use.

1:1 akadama to lava or pumice fine for deciduous

This is location dependent, if I use the traditional 2:1:1 the trees dry out too quickly requiring frequent waterings here in central Texas. I am using 100% akadama, 80/20 akadama:kyriu, or 80/20 akadamaumice depending on how much the tree likes water.

 

[Jrmcmich]

It all depends, it is a good mix for propagation and for small (shohin) and smaller pre-bonsai, anything bigger (that will shoot a leader a few feet long) and you will have an issue with the wind moving the tree in the soil until its root ball becomes intact. I am using inorganic soil for my pre-bonsai, Monto Clay, Bonsai Block from Bonsai Jack and pumice. The advantage is that once I take the tree out of it I can rinse it, let it dry in the sun and re-use.

This is location dependent, if I use the traditional 2:1:1 the trees dry out too quickly requiring frequent waterings here in central Texas. I am using 100% akadama, 80/20 akadama:kyriu, or 80/20 akadamaumice depending on how much the tree likes water.

Good points. I also find it harder to tell when perlite is dry compared to pumice. I wish Pumice was cheaper as did pumice with a small amount of peat for some collected trees. They all seem to like it. I was originally using straight pumice but was worried would dry to fast so added peat to it for some retention.

Definitely don’t like how light perlite is but definitely cost effective.

 

[Paradox]

It all depends, it is a good mix for propagation and for small (shohin) and smaller pre-bonsai, anything bigger (that will shoot a leader a few feet long) and you will have an issue with the wind moving the tree in the soil until its root ball becomes intact. I am using inorganic soil for my pre-bonsai, Monto Clay, Bonsai Block from Bonsai Jack and pumice. The advantage is that once I take the tree out of it I can rinse it, let it dry in the sun and re-use.

This is location dependent, if I use the traditional 2:1:1 the trees dry out too quickly requiring frequent waterings here in central Texas. I am using 100% akadama, 80/20 akadama:kyriu, or 80/20 akadamaumice depending on how much the tree likes water.

Yea for deciduous I have also seen people use 100% akadama.
I have a maple I bought that came in 100% akadama
Even up here its not a bad mix for a mapel or other moisture loving tree

 

[Vincent Tanner]

Hey, man. If you need soil components, our club, the Bonsai Society of Hartford, has a bunch of 18L bags of akadama, pumice, and lava for sale cheaper than you’d usually find at a retail place (plus no shipping!). Our summer picnic / auction is later this month and you’re welcome to come. Depending on where in the state you live, it might be worth swinging by. Feel free to PM me if you want more info.

EDIT: And if you only need enough soil for one tree, an 18L bag of each component might be a lot. I could make you a pre-mixed gallon or whatever size