Rude people on both sides of the debate SUCK really hard. In a bad way. Childish actually.
If the following discussion seems condescending to you, (you are already aware of this information and already agree or disagree with it) it is not meant to be and is not meant for you anyways.
I’ll throw in my observations from 30+ years of growing or learning about “bonsai.” Most of those years was before I acquired “good” bonsai knowledge now readily available from so many sources as well as before so many “good” readily available soil components were easily found.
I’ve had two bonsai lives. The first period of 15 years consisted of growing “sticks-in-a-pots”(SIAP). This was my trail-and-error phase. I consumed what limited books and articles I could source voraciously (luckily subscribing to every issue of “Bonsai Today”). I was already quite good at successfully growing garden plants and vegetables in the ground and standard garden pots. I have always had a green thumb even at a very young age. I have even grown a successful small vineyard sufficient for making my own wine.
Growing trees in SHALLOW containers seemed easy enough until I realized most of what I was trying to grow either died or languished in relative short order. I was perplexed since I could grow just about anything else I tried to grow in my Texas environment. I joined the local club and read more books and realized I needed to switch from potting soil to “sifted aggregates.” I proceeded to use everything one can think of and some you’ve probably never heard of before. Lol.
I discovered particle size was most important regardless of soil component. Dust holds too much water for too extended periods of time and leads to root death and subsequent rot. The shallowness of most bonsai containers does not exert enough head pressure to force out excess water. So removing dust and the smallest particles helps reduce the adhesion of water molecules and helps purge excess water from the container.
Soak a sponge and hold it flat [bonsai container] till it quits dripping, then stand it on end [standard nursery can] and see how much MORE water drips from it. Those new to bonsai will instantly understand what issues this SHALLOW growing enviroment presents.
I sifted the potting soil. Trees faired better, I used sifted pine bark, decomposed granite, Turface, expanded shale, play sand, greensand, perlite, vermiculite, peat moss, sphagnum moss, lava sand, decomposed oak leaves, on and on.... nothing worked as well as I wanted. Then one day I was at Dallas Bonsai Garden to buy some nice ceramic bonsai containers. Fred Meyer, the owner, asked if I wanted a bag of akadama to add to my purchase. I said ‘no’ initially. It was and still is very expensive! He convinced me I should try it with a few of my best trees. By that time I had a few decent trees that no longer would be classified as “SIAP.”
I repotted a few of my better trees in my current mix of that time and amended with a generous proportion of akadama. A few years later during repot of those same trees I was blown away by the density of fine roots and overall improved health of these trees. Needle to say, akadama became in invaluable component in my soil mix though the rest of the components continued to change over time.
Life got in the way for about five years. I stopped bonsai and relinquished all my trees.
My situation eventually changed so I once again could resume my love affair with bonsai. This time I knew exactly what to do so I did it. So my second bonsai life began.
I visited literally every garden nursery within an hours drive of the DFW area that first year looking for and buying “trunks” regardless of species. I collected a few trees from the wild too.
In just 10 short years my collection is light years from where my collection left off the first go-around.
My current standard soil mix for most of my trees in REFINEMENT consists of varying ratios depending on species of akadama, perlite, lava, diatomaceous earth and kanuma (because I have too much of it). I would switch the perlite to pumice if i could find a reliable, inexpensive local source. Azaleas are in 100% kanuma.
All my deciduous, broadleaf evergreens and azaleas in DEVELOPMENT are now grown in deep 15-20 gallon buckets in 100% coco coir peat and fertilized heavily. Most of my “SIAP“ are now transformed into impressive trunks in 3-5 years. Azaleas not so much. Lol.
Trail and error to say the least!
My major bonsai milestones:
Subscribing to and collecting every issue of “Bonsai Today”, sifting soil components, joining local club, adding akadama to my mix, using coco coir peat in deep pots to rapidly develop “SIAP” trunks, switching to APL, adding diatomaceous earth to my mix, using exclusively organic fertilizers, using tea bags for all my fertilizer applications, top dressing with shredded New Zealand sphagnum moss, joining Mirai Live.
Needlesss to say, USE WHAT WORKS BEST FOR YOU, your species of trees, local growing conditions and what you have available to you and what you can afford.
Trail and error never hurt anyone (don’t breath the dust!), it simply kills lots of trees over time and you learn!