edisonrich
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Organic Soil Items

What items can I use for organic soil in a bonsai mixture. There are many items I see listed for inorganic but very few for organic. The only ones I have noticed are pine bark, fir bark, and peat moss.

tomc
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Re: Organic Soil Items

edisonrich wrote:What items can I use for organic soil in a bonsai mixture. There are many items I see listed for inorganic but very few for organic. The only ones I have noticed are pine bark, fir bark, and peat moss.
Trees need air (and secondarily) carbon (as host to mycellium) around their feet in shallow pots.

Except for trees in the tropics, or azalea, there should be little peat in pots. It slows air exchange. If you can not or will not use soluble fertilizer, use osmocoat pellets. Adaquate finished compost can be applied on the head of a pin...

If your bench isn't in Sao Paulo, or Saigon, skip the peat moss and compost.
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rainbowgardener
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So what about the bark chips? Seems like I have seen those in bonsai soil recipes?
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tomc
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Using a gallon scoop:

5 scoops sifted crushed granite *, **.
5 scoops sifted crushed bark mulch #

Using a 2 cup scoop
1/2 scoop crushed sifted oyster shell

Mix all in a wheelbarrow.

*: Particles too big, will not pass through a 1/2" hardware cloth screen.
Particles too small will pass through a 1/16" hardware cloth screen.
Do not use either, discard to garden or drive way.

**: I used to buy bulk granite grit at gravel mills. Retail amounts are on sale at farm stores as chicken scratch (50#)

#: Pine bark has been more finely ground, by my trial.

Organic fines, like peat moss may be added to specific tree soil. Um, like azalea and bald cypress.

If you have very deep pockets, some cinder-block mills buy heat expanded shale, which has a nice dark dirt color at only eight times the price of crushed granite...

My oldest child described bonsai soil as: "Looks like a bag of rocks with a little bark mulch dragged through it". Her assessment is apt.
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tomc
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When an Englishman described the soil in a pot around the feet of his plants or trees, s/he often says 'compost' as a generic and global term.

Often when an USain says compost, s/he means the stuff of a compost bin.

Very often 'organic' and 'compost' get muddled and transposed.

I believe the original question had this topic correct, that of 'organic' means any once living material in a soil mixture.

The problem pops up that trees need very fast draining soil with a high percent of air in the mix. Soil with very small particle size, like loess or peat don't outgas well. making anoxic soil that drowns woody plants in tiny pots.

If you spend much time rummaging around at bonsai sites looking at photos, you will at times see trees in their pots wedged up at an angle. This is to improve drainage of the soil in those pots.

Its only in the tropics that you will see bonsai soil with higher amounts of peat or sphagnum in their soil mix. So if your growing in San Juan, get your soil training locally... ;)
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