Gday folks!
Recently, a friend scanned a copy of an article titled
The Horticultural Aspects Of Australian Native Plants, by Dorothy Koreshoff (
Bonsai Australis magazine, #3 1993). In the article, Mrs Koreshoff goes into detail about how Bonsai soil works, and what traits are required for healthy (Oz native) plant growth.
Dorothy Koreshoff wrote:...despite any particular condition that prevailed in the original habitat, the requirements change when grown (in any type of conatiner) above the ground. Thus horticulture is simplified, basically, if one ensure that:
(a) air is able to reach the roots at night; and
(b) there is free not locked water (some water is held too tightly by fine particles to be of use) which is able to be absorbed by the roots during the day...
She goes on to describe her Bonsai mix, which consists of crushed stone (2-5mm) and cow manure (humus), mixed at a rate of "four units of stone to one of humus". Now, this is a much simpler soil than described in
Bonsai With Australian Native Plants, and as such, I thought I'd give it a go (with a few tweaks to allow for my local conditions and availability of ingredients).
Here's the analogous mix I came up with, using only ingredients at hand:
12 parts washed* granitic sand (~2-8mm) and/or crushed basalt (~4-8mm)
2 parts** sphagnum moss (whizzed briefly in a blender with lots of water)
1 part** Dynamic Lifter pellets
I have recently repotted nearly all of my trees (native and non-) into more-or-less this mix, and I don't know if they've ever been happier. Most of my trees are currently in oversized training pots, but as they find their way into Bonsai pots, I may need to remove the larger (~6-8mm) particles.
I'm sorry to have gone off-topic (this is not strictly an inert mix), but I thought it was worth offering up here. I'm happy to move this post to another thread if anybody has any issues with it.
Thanks.
Fly.
* Granitic sand is sold as a topping for pathways and the like. In order for it to compact and harden in such applications, it contains generous amounts of clay. If this clay is not
thoroughly washed out (sifting is not sufficient), the mix will turn into something resembling a mud brick, holding unusable moisture and preventing air penetration. Trust me - I know...
** The sphagnum and Dynamic Lifter constitute the 20% humus in the mix, and are my replacement for cow manure.