Author Topic: Why Should I Sift Bonsai Soil?  (Read 8550 times)

kostas

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Re: Why Should I Sift Bonsai Soil?
« Reply #15 on: March 14, 2012, 05:25 PM »
Because this stuff forms solid concrete in the bottom of the pot!

Do you sift?
it depend of the species! for example  tamarix that needs high humidity its not necessary to sift and the tree respond very well also it depends from the type of soil that someone can use. so for me some time i sift and some others i don't.
 

rockm

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Re: Why Should I Sift Bonsai Soil?
« Reply #16 on: March 15, 2012, 09:38 AM »
Tsk, Tsking? Hmm, well you have told me by golly!

John, sorry if I lost my sense of humor. It wasn't really apparent from your posts that it was tongue in cheek. Much  non-verbal communication is lost on the web.
 

nathanbs

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Re: Why Should I Sift Bonsai Soil?
« Reply #17 on: March 15, 2012, 10:09 AM »
i think kostas makes a good point. There are some species that perhaps like less oxygen to their roots, more than fine bonsai soil can provide. Others definitely could/would suffer by not sifting hence Boon being able to make a simple observation of the trees health. However my guess is that not sifting soil goes hand in hand with other lazy habits that would all contribute to the less than ideal health of some species of trees.
 

scottroxburgh

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Re: Why Should I Sift Bonsai Soil?
« Reply #18 on: March 16, 2012, 01:26 AM »
...my guess is that not sifting soil goes hand in hand with other lazy habits that would all contribute to the less than ideal health of some species of trees.

That hits the nail on the head!
 

John Kirby

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Re: Why Should I Sift Bonsai Soil?
« Reply #19 on: March 16, 2012, 01:46 PM »
Yo, ho, ho. More sifting this weekend, Boonarrives to work with me (repotting among other things...) on Wednesday evening.... Must be prepared....
 

Chrisl

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Re: Why Should I Sift Bonsai Soil?
« Reply #20 on: March 16, 2012, 02:54 PM »
LOL  I'm taking a break from sifting right now...gotta find a more comfortable chair...my lower back is suffering lol
 

John S

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Re: Why Should I Sift Bonsai Soil?
« Reply #21 on: March 22, 2012, 01:27 AM »
I'm a member of the Bonsai society of Portland and last month we had a mentorship meeting on soil making, porosity and permeability. Our club recommends Boon's soil and so this is what we made. While I was discussing the subject on another bonsai forum I was surprised by how many people were so adamant about not sifting, saying it was just a waste of time. This is a pretty good site that I was on with some very impressive trees, and I'm a relative beginner, however I decided I would type up a synopsis of what we had learned at our meeting and some site members found it very compelling. So, here it is for what it's worth, I think soil sifting is important and at the very least whatever soil you use absolutely, positively has to be watered in until any residual dust is thoroughly run out of the bottom. If it's not it will clog the soil and it won't matter whether you sifted for size or not. So without further ado here's my write-up on the subject, not saying I'm an expert this is just what I learned from some who were closer to expert than I....


Okay, so here's what we talked about last week. There are two main principles to consider when discussing soil, permeability and porosity. Permeability is sometimes also referred to as Hydraulic Conductivity, and is a measure of the ease at which fluids move through a soil. Permeability is determined by the void spaces, or air between different particles in the soil and in general the more consistent the size of particles and the larger they are the larger these spaces will be. When particles of various sizes are intermingled, the smaller particles tend to settle in the spaces between larger particles and this can act like a plug in these areas, slowing down the movement of water.

Another thing is happening when you water. As water moves through the soil it creates a suction force that draws oxygen into the soil layer. Oxygen is very good for plants roots as it helps them in absorption of vital nutrients, namely your fertilizer. Proper aeration of your soil can significantly increase the growth rate of your tree, and as we all know increasing the speed at which our trees grow leads to more mature primary and secondary branches, thicker trunks, and better nebari than if we grew in murky, muddy, dense soil that we see so often in mallsai. So in these terms the more permeable the soil, the greater the availability of oxygen to your trees.

The second thing to consider with soil is the porosity, or amount of open spaces in soil particles themselves, or between soil particles than can be harnessed to hold water. This is very important for people who are using completely inorganic soil mixes, as the lack of naturally water holding organic elements such as bark, silt, compost and dirt leaves us needing water absorbing stony elements that can hold onto water long enough for it to remain available to the trees. Elements such as akadama, sophisticat, diatomaceous earth, pumice and lava rock all hold onto water to differing amounts. Before I go any further I think I should go into the theory behind using a totally inorganic soil for trees.

We gain a lot of permeability in the soil by using inorganic, rocky soils. However we lose some water holding power as well as the natural nutrients found in organic elements commonly found in soil. It seems like it would be simple enough to mix some organic elements into the soil, right? Well this actually has a couple negative side effects. First it slows down the rate at which water can travel through the soil, and how quickly air can move through as well as filling in space that can give the roots access to oxygen. Secondly when we fertilize, the organic compounds will end up absorbing more fertilizer than the rocky elements. If too much fertilization takes place it will build up in these organic elements and can result in too much of a good thing. By going to a completely inorganic fertilizer we are able to administer and monitor exactly how much of any given nutrients our trees get. There is no threat of burning the roots because by the very nature of inorganic soil, and the fact that it can hold less water, watering frequency needs to be increased. Because of this, any excess nutrients in the soil will simply be flushed out. So this means we can fertilize more often and increase the growth rate of the plants even further.

I have never used 100% akadama as a planting medium, but it has been used that way for years by many bonsai enthusiasts. What I have seen is what akadama looks like during a replanting. Akadama is a relatively soft soil constituent and through it's use, breaks down into gradually smaller particles the longer it's used. What this results in is a settling in the pot, where permeability is minimized and both water and oxygen move more slowly through the water column. In some cases water may actually not get to certain areas of the pot because there is simply not enough space between particles for it to travel so the water just goes to the path of least resistance. This compaction can result in poorer health of the tree and its roots. In terms of permeability having largely varying, (in terms of size) soil constituents, we end up with a similar situation to the compaction we see in the akadama.

Now, while I think there is some validity to this in terms of the value of separating very large from very small particles, I don't think it has to be done to the extreme. What I do is filter out the very largest particles of my soil blend, all of whose elements were screened to 5/16" before being blended. My mix was sieved then using a 1/4" screen and what didn't pass through becomes the soil for my very largest trees. The next screen down screens out the very smallest particles, I think it screens to 1/8", and the larger of the particles go into pots for shohin's and mame's. What's left is very fine and can be used for top dressing on all trees, as the finer material aids in production of moss if that's your thing. I think adding the finer material back to the top can result in some settling back into the lower part of the soil, but I think it's really minimized by separating it out first and putting it on top. An important note is that due to the relative softness of akadama and the abrasive quality of both the screens and the other rocky elements in my blend it is possible to screen it until it is all powder. When I screen I give the soil a few swishes through the screen, but don't overdo it. No sense turning the most expensive stuff in there, into silt.

As many have pointed out it's imperative to water in any freshly planted trees thoroughly. This helps rinse out any soil clogging silt or dust that also has the effect of minimizing permeability. I water until the water runs well clear, and then for maybe a half minute more, making sure that all corners of the pot are soaked.

Now, I'm not saying this is the gospel on soil, or that if anyone's personal soil mix is working fine for them they should all of the sudden change what they've been doing. This is merely the information that has been presented to me and my best distillation of that info. Hope your minds are not as numb as mine is now, I'm going to go try and pass out!
 

rockm

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Re: Why Should I Sift Bonsai Soil?
« Reply #22 on: March 22, 2012, 02:53 PM »
All well and good, except there are more than one kind of Akadama. Some is high fired and doesn't break down. Same is true with other inorganic ingredients, like haydite.

 

John S

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Re: Why Should I Sift Bonsai Soil?
« Reply #23 on: March 22, 2012, 03:16 PM »
All well and good, except there are more than one kind of Akadama. Some is high fired and doesn't break down. Same is true with other inorganic ingredients, like haydite.



I should have clarified, this was double red line akadama in our mix.
 

Elliott

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Re: Why Should I Sift Bonsai Soil?
« Reply #24 on: March 22, 2012, 04:32 PM »
I am a compulsive sifter ;). I actually enjoy it! it relaxes me. I'm not an anal retentive person, but I like looking at the rows of covered tubs under one of my tree benches that have all my different inorganic soils sifted and separated into 3 sizes.  I don't put a mix together until I'm about to re-pot so i can customise the mix (more akadama -the hard stuff- for broad leaf, less for conifers).
 Now, if i could just learn to style trees..........
 

Larry Gockley

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Re: Why Should I Sift Bonsai Soil?
« Reply #25 on: March 22, 2012, 10:08 PM »
Sifting seems to be a very very low price to pay, needed or not. This post reminds me of other posts where someone asks how low a temperature the plant can endure before it is dead. I care about my trees too much to even think about taking a chance, but then I don't walk my dogs without a leash either, Murphy's Law. you know. Larry
 

nathanbs

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Re: Why Should I Sift Bonsai Soil?
« Reply #26 on: March 23, 2012, 09:44 AM »
All well and good, except there are more than one kind of Akadama. Some is high fired and doesn't break down. Same is true with other inorganic ingredients, like haydite.



I should have clarified, this was double red line akadama in our mix.
I have noticed that the double red line isnt actually that hard compared to others. I noticed that while sifting you can feel the granules hitting the side of the sifter and it feels like you are shaking around a bunch of little rubber balls. Other brands ive discovered that while sifting they feel harder and make more noise when hitting the side of the metal sifter, almost what you would expect from a light rock rather than a rubber ball
 

John Kirby

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Re: Why Should I Sift Bonsai Soil?
« Reply #27 on: March 23, 2012, 10:45 AM »
The Double Red Line Akadama story is complicated. There are several products in the Double Red Line stable, including their Soft Pumice Akadama (that is what most of us get when we buy Akadama) which is a dug/low fired product. There is also the high fired product that you can buy from several sources in the US (I last purchased from the House of Bonsai in CA a few years ago). It is very hard and functions differently than say the soft pumice. So, if you want the really hard stuff, you need to ask for high fired. I use the soft pumice style Akadama, double red line this year. One thing it is darker than some other brands we have used. I am looking forward to the day when we can purchase American "akadama", a volcanic clay that is ground down into a soil absorbent like turface- which can function well, but differently.
 

Chrisl

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Re: Why Should I Sift Bonsai Soil?
« Reply #28 on: March 23, 2012, 10:57 AM »
"Here Here!"  I'd love to try Akadama, but I have too many trees in a very early stage of development and I simply can't afford it.  I'd rather be able to buy better material for now.  But someone could make a good business of making an "American 'Akadama'"!
 

akeppler

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Re: Why Should I Sift Bonsai Soil?
« Reply #29 on: March 23, 2012, 03:14 PM »
"Here Here!"  I'd love to try Akadama, but I have too many trees in a very early stage of development and I simply can't afford it.  I'd rather be able to buy better material for now.  But someone could make a good business of making an "American 'Akadama'"!

You can read about a source here.

http://bonsaistudygroup.com/general-discussion/calidama/msg6197/#msg6197