Correct soil for 3 year old JBP

[Bonsaidoodles]

First post here.

Living in Centurion, South Africa.
I need to repot my japanese black pines. They're about 3 years old.

I've looked everywhere for information on what soil to use. And there is a lot of conflicting information. The only common denominator is to use Akadama mixed with other things.

I only know one place that sells akadama, and it is way out of my price range. I don't have much disposable income. I also can't find crushed leca, however I can access leca balls and manually crush them. Though the sizes won't be consistent.

I can also access river sand, perlite and pine bark. I can do peat, but I've seen people specifying long-fibered peat. Mine is definitely not long fibered.

I found a small amount of lava rock at an out of the way shop once. It seems to be what they are currently planted in from when I purchased them. However whatever mix I make won't be able to use the lava rock as a large percentage of it.

The pots I am planning on using are round aero pots like these: https://www.bonsaitree.co.za/collections/plastic-containers/products/round-aero-pot-1-3l-14cm-x-16cm
They are currently in very tall and thin plastic pots. Presumably for root over rock/cascade. I would like to keep at least one of them for root over rock. However I don't have any good alternative pots for them right now, and can't find a bigger tall and thin one.


It does get to be over 30 celcius quite often in summer. And so I'm concerned about being too free draining and having to water more than once a day. But more concerned about root rot.

These are young trees that I'm mostly leaving to grow big and strong. Not finished trees.

Does anyone have any advice on what soil would be best using affordable materials?

 

[Shibui]

I'll throw another conflict into the mix for you. I grow pines but do not use Akadama. All species here grow in the same soil mix. It is way too complicated for me to manage different soil mixes for hundreds of different species and different pots.
Trees will grow in all sorts of soil mixes. IMHO it's more about matching your care and watering to the soil mix rather than making the soil mix for each different species.

I can also access river sand, perlite and pine bark. I can do peat, but I've seen people specifying long-fibered peat. Mine is definitely not long fibered.

I used coarse river sand and fine pine bark for many years with few problems. Perlite is a good additive but be aware that it is very light. Tends to float out of the soil mix when you water and pots can be so light they blow off the benches when it gets windy. Long fibre peat is probably sphagnum moss. There's a lot of confusion because of different terms for these components. I know some growers use some peat in their mixes but I use a freed draining mix so that it doesn't hold too much water. Why add something that's going to hold more water?
In the end you can use a wide range of ingredients to make soil mix. You'll need to find components you can afford that also give a mix that has all the qualities you need - water holding capacity, Air filled porosity, weight, etc.
Do not discount commercial potting mixes, especially for smaller quantities. Some of our club members grow very well in commercial Cacti and Succulent potting mix. For a few years I just used a premium commercial bagged potting mix from the local nursery.

Take care when using mesh pots. I've found they dry out much too fast in our hot, dry summers (often over 40C!). Trees seem to do as well or better in traditional black plastic plant pots here. Others are reporting that they do better with a mix with more water holding capacity when growing on in mesh pots. By all means try some out and see what works for you but just be aware mesh pots are not a magic bullet despite some of what you will read.

 

[SeanS]

Bonsai Tree sells crushed LECA, that’s where I get mine

Crushed LECA

Elevate your gardening with Crushed LECA, the durable, organic-free growing medium that enhances drainage, aeration, and plant health for all enthusiasts.

www.bonsaitree.co.za

 

[Bonsai Nut]

You do not need to use akadama to grow JBP. I use it in my soil mixes in North Carolina, but in Southern California I would often use 100% pumice, or 90% pumice with 10% screened pine bark fines, and my trees were quite healthy. Of course in Southern California I often used mesh pots, and would water twice per day, so I wanted a soil mix that would drain freely, while staying moist (but not wet).

 

[Potawatomi13]

100% 1/8-"1/4" pumice if available. Japanese dirt is not magical.

 

[SeanS]

Pumice soil components aren’t locally produced in South Africa so we also have to buy the Japanese sourced stuff, just as with akadama.
Suggesting pumice puts the OP in the same boat as he is with akadama

 

[MrFancyPlants]

It sounds like leca or better crushed leca would be great components. Call me old school, but I think home made compost could be a great combination of sifted to same size as leca. Sifted river sand could be another great component to mix in as needed.

 

[River's Edge]

Based on what is readily available to you and how you describe your desire to keep it cost effective I would combine river sand and pine bark. Take care to sift and use similar size particles. Be prepared to change out when drainage slows with the pine bark decomposition. Some will last better than others. Upper trees are very young as pines go so there is lots of time to test out changes to the substrate. Until you are very comfortable with the mix and care routines avoid the mesh pots and colanders. They can be very effective but they require more experience to know when they will suit the circumstances. Use a bit larger containers when in the early stages until you become comfortable with routines. Growth is a prime objective at this point and you have a decade or two to work on it before focussing on refinement. All the basic growth and development can take place in a wide variety of soil mixes.
Seek local advice for the best available sources of river sand and variety of pine bark.

 

[SeanS]

I started out using crushed LECA and coco-coir with reasonable success in South Africa. Crushed LECA is probably the most reasonably priced “fancy” soil component, behind perlite which is around R350 (including shipping) (around $20) for 100L from Pratley. Coco-coir is also cheap as chips and goes a very long way once rehydrated.