Best type of soil for wooden growbox

Hello Mirai community.

My plan for the oncomming spring is to put an acer air layer into a wooden box.
My question is, what soil type is best to use to promote as much growth as possible.
is a 1 : 1 : 1 akadama lava pumice ok, or are there better alternatives like only use pumice?
i find alot of soil mixes for refinement, but nothing for much growth.
I know that placing it in the field is best, but that is not an option. :sweat_smile:

The plan is to grow primary branches since there are none of them on the trunk.

I live in Belgium.
Thanks in advance.

PS: sorry for any spelling mistakes :smiley:

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For getting growth, a 50/50 mix of pumice and bark or peat or other organic.

I use that on all my air layers after separation.

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Thanks for the reply.
I forgot to mention that, this air layer was separated in september 2019. I have put it in a plastic container, and let it rest for a whole year. Must this be treated differently than immediately after separation?

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That doesnā€™t change it for me. In my experience, if you want rapid growth (no matter how recently it was separated) , pumice and bark is a good mix for aeration and nutrition.

Once you start adding akadama, the growth slows and that starts the refinement process.

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+1 for the pumice and bark approach in the grow box. Provides good balance of o2/h2o as well as aides the aim of the grow in grow box.

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what am i missing if i use straight pumice?

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Cation exchange capacity is dismal in pumice.

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Per B. Bentley - If CEC is lacking (which a pumice as pure SiO2 would be) adding some horticultural charcoal or bark or both would likely help.

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I have heard of the cation exchange capacity to be low on pumice. But it aint zero. Despite the low score, I havent experienced any bad effects of using pure pumice. Im actually cutting back, about half way, how much I fertilize this year because of how much my trees have taken off. I work with mostly yamadori and the trees in nature have even worse soil conditions.

Maybe it is because I insist on using only liquid organic fertilizer. I think there may be room to explore and experiment in the efficacy for pines by using pumice and liquid organic fertilizer

I wasnā€™t saying that youā€™re doing it wrong. You asked what youā€™d be missing with 100% pumice and as far as I know thatā€™s it. Well, that and scaling of the roots. I also use 100% pumice and fish emulsion in my yamadori boxes. :man_shrugging:t4: No way of knowing if a plant would do better with organics without experimentation. My area is so humid that I didnā€™t feel the need to add bark compost to the mix. I think I may try it in one or two of the boxes I have planned this spring. Weā€™ll see.

This year Iā€™m going to experiment with chemical ferts in my yamadori boxes. Specifically Dyna-Gro Bonsai Pro. Iā€™ve used bio-gold in my yamadori boxes last year. I didnā€™t like the way it caked up at the surface. It broke down faster than it broke down on my bonsai pots though, so thereā€™s something to be said there I guess.

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If the CEC is lacking with pumice, can it be replaced/added in the soil mix with zeolite?

Interesting. Iā€™ll have to see how that compares to pumice in terms of price. Does zeolite make the water readily available like pumice? If you want to add a nutrient component I donā€™t think you can go wrong with a type of bark. Iā€™m using pine bark this year.

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In europe, i can buy zeolite for almost the same price as the pumice.
I have found this shedule a while ago, Bonsai compendium - Google Sheets
i donā€™t know that it makes the water readily available, but looks like it has a lower water retention.

i also do not know how accurate this shedule isā€¦ :sweat_smile:

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There was a good thread on zeolite a few years ago that is maybe worth revisiting.

IIRC Zeolites arenā€™t readily available in the US but maybe there are some sources out there.

Before getting into bonsai, I got some of this zeolite mix for houseplants. It was pretty good, but maybe a bit pricy (especially compared to garden center soil) so I stopped buying it but worked well. Every so often I think about buying another bag just to see how it would stand up with bonsai.

https://www.lechuza.us/accessories-lechuza-pon/lechuza-pon-1.4-us.dry.gal/19561.html

From the website the mix is:

  • Zeolite
  • German washed pumice
  • German, light Lava (permanently supplies your plant with iron)
  • Fully-coated, premium-quality fertilizer.
  • The coating is purely organize and breaks down without leaving any residue.
  • The fertilizer supplies your plant with nutrients for up to 6 months.
  • Fit for all plants, including foliage, flowering plants like orchids, citrus plants, herbs, tomatoes, fruit trees, cacti, and more.
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I purchased plants from Meehanā€™s nursery once. I asked them what they use in their mix. They said perlite, bark, haydite and turface. The roots this mix produced were pretty fine though.