Hi, vermiculite is not a good addition as it compacts very quickly and won't help "free drainage". Potting soil (usually 90% peat) is the scourge of bonsai as it holds water much longer than you'd want and roots rot easily. Forget the charcoal for now, it's pretty irrelevant (as is being too concerned about pH - it's generally not much of an issue except in plants needing extremes to survive). Perlite's ok, but not that attractive - it's more useful for germinating seeds than otherwise. Your first component is the main one for all bonsai, with the addition or subtraction of various kinds of organic components such as small bits of fir bark, very occasionally sphagnum moss, well rotted compost, and possibly coarse, porous soil from a nursery (not peat based!). Different trees need different amounts, i.e. pines are happy in almost all grit, with only a little bark added, whereas elms are more likely to do well with a little more water holding organic stuff, but still more than about 40%. Your olive particularly won't be happy in your present mix for very long and really likes to get pretty dry between waterings, the elm less so. I personally find easily accessible gravel for aquariums, with or without other grit and/or organics to be a great basic choice. It's more about the inherent water handling properties of the ingredients than the thing itself.

Another issue would be whether you want your trees to grow only slightly over a relatively long time - e.g. are they mature, already trained pretty much as you want them to be indefinitely (aside from minor pinching for neatness) vs do you want them to grow fat trunks to simulate age, in which case a bonsai pot is not the best place for them as it stalls real growth very much. You'd be better off the plant the tree right into the ground - the fastest way to grow it out, or at least in a large training box that can be moved into a sheltered location (unheated porch) in winter, though it wouldn't apply to the olive, of course where you live. BTW, make sure any hard frosts have passed before putting out the elm this year. Go to www.bonsai4me.com for a lot of basic info. and www.bonsaisite.com (more active than this place :-).

Hi - that was meant to read "but still NO more than about 40%" (middle of 1st para).

Larke,
Thank you for the information. The reason I added a small amount of potting soil is because several articles I read suggested adding a small amount of organic material to the bonsai soil. I figured that one part potting soil out of 6.5 was probably not going to cause excessive water retention but I'll keep a close eye on it rather than re-traumatize it for now. I am very curious about your using aquarium gravel as the Naka manuel as well as a few other sources specifically discourage it and I would love to know why since at first glance it would appear to be a good medium for bonsai. In fact, the course sand in my mixure is an aquarium sand that is all natural and quite gritty and supposedly chemical-free. I did rinse it prior to using it to minimize any chemical residue anyway. If you know why Naka advises against it I'd be very interested to know as well. I think perhaps he was referring to colored aquarium gravels or those with additives. Thanks again!

I hope this doesn't end up in another attack about soil but here goes...

Most of us find, after some years, that simple is best for something like soil mix. I lived in the eastern US for quite a while and most of the people I knew, myself included used only an inorganic component and an organic one. The inorganic would be something like coarse Turface or Haydite (or something similar) and the organic would be Pine bark. Both screened to remove the fines before mixing.

You vary the mix acording to the tree; a higher percentage of the organic for tropicals and deceduous, lower for pines and junipers. The mix can last for as long as 5 years before it needs replaced.

For me, now, this is a moot point...the only thing here is sand, sand, more sand and crushed stone.

Bob

As far as the aquarium stuff goes, I think it might refer to painted stones, but you can get natural colored ones all over, plus I also think the "sand" referred to in many books (and in Headcutter's native Vietnam) refers to 'river sand', which is not either our beach sand (way too salty for 99% of plants) or play sand, which is much too fine. We don't really have the same river sand here, so need to use a small grade grit of some kind and I know others who use aquarium gravel (of whatever size) with no trouble at all.

Thanks again to Larke and to Headcutter. Now, Headcutter, I take it you are in Vietnam? Why would you not be able to get organic material for your soil there? And your nick name....just curious.

Yes, I live in the little town of Tuy Hoa on the south central coast, been here for almost 4 years. There is no need for anything like that here so you just can't buy it. Closest you can come is ground coconut shell and it dissolves and turns to mush in a few weeks.
I was blessed/cursed with the ability to 'see' a design. I can look at a tree for a few minutes and 'visualize' what it should/could look like in the future...I have the guts to make the first cut.

Ya know what Rod says...

Bob

"The first cut is the deepest....baby I know.....la,la,la" :)
Are you a Vietnamese? If not, wht the heck are ya doin' there?

I'm American, was here for a while during the war, decided to come back a few years ago to teach English and work here. Sold off everything including a field of about 800 trees in various stages of development and moved. I'm semi-retired so I can travel here a lot, started rebuilding a small collection of trees over the past few years.

I only kept a few tropicals in the states so being here is like being a kid in a candy store.

Bob

I think that the "sand" issue revolves around particle shape as well as particle size and possibley parent material. River and beach sands have round particles and for reasons that are unclear to me this shape tends to retain more water. "Sharp" sands come from crushed parent material that has not been tumbled in water and they seem to drain better. It probably has something to do with the ratio of air space to water film thickness. I use a completely inorganic mix which is one part pumice (Dry Stall), one part scoria (crushed lava rock) one part Cal-Adama (crushed hardpan) all screened. Both Dry Stall and scoria are available in NJ but not Cal-Adama. You could probably substitute a coarse grit or crushed granite chips. Be sure to screen or wash out as much of the fines as you can. Particle size should be 1/8-1/4". The pumice and scoria both have many tiny spaces in the particles which hold water so sand made from these materials holds more water than granite that has no such spaces. You can adjust your water holding capacity by adjusting the ratios of these materials. If you want to add an organic component to your mix I would recommend small orchid bark (1/4" fir bark). It decays pretty slowly. I would not have more than about 10% bark in any mix. Welcome to the wonderful obsession of bonsai. Jack

Jigi - you may find the thread I'm going to link you to below of interest. At the end is a recipe (gritty mix) that I have been using for more than 15 years. It is extremely simple, durable, and adjustable for water retention. If, after you've read the thread, you feel I might know enough to be of some help, we can have a detailed discussion.

Al

Here is a link that might be useful: About soils - water movement and retention

Hi, well this is a very interesting article from someone who's been doing bonsai a long time, but I would like to point out that the some of the issues addressed in the article have also been looked at by others (of expert reputation) and occasionally found to be different (big suprise - soil is very controversial in bonsai and there will always be many opinions). As far as the perched water table goes, Brent Walston of Evergreengardenworks has a theory in "www.evergreengardenworks.com/earthpot.html"; which may not agree with the one here, plus science is coming up with new ideas every day. Very often what may 'still' work for someone who has used a particular formula for many years, has been proven to not be ideal if put against new versions of the same thing, so it's important to do a lot of research and find what works for you over time. No one theory will work for everyone or every tree in every environment. and we all will interpret things differently, but it's nice to have so much input out there!

Perhaps you would be specific in what you disagree with, or what you think Brent might disagree with in the article I wrote. I'm very interested in what might have caused you to discount it so easily. I'm more than willing to discuss the chemistry/mechanics of soil science and particularly the physics relating to water movement and retention with Jigi, without centering on any one soil as 'the best'.

Al

I haven't discounted anything, but was just advising newbies that there are a lot of different 'takes' on soil and that while something (your recipe) may have worked very well for you for so long, there are also other ones out there, some newer and possibly based on newer science (or experience) that may also be good. Maybe I wasn't very articulate about it and that might be because I did not cite more than one article (and in fact wondered if it was even the one I'm remembering that Brent wrote - might have been in his blog, in fact - that sort of disproved the need to worry about perched water tables in small potted plants).

If you think it's about a recipe, you missed the point entirely. What I'm hearing is there is nothing in the article you would personally challenge, but you think there's a chance someone else might. A slight variation of the article was published in the Journal of the ABS not too long ago, and as I remember, I/it didn't receive any critical commentary.

Al

I believe Larke was clear in his explanation. He's saying that what works well for one person-in one particular envoronment-will not necessarily work well for another person-in a different environment. Conversly, while one species of tree may grow very well, in a particular 'soil', in one particular environment, could be death to another.

IE: the 'soil' mix I'm using here I wouldn't dream of using where I lived in the US. However, the mix I used in the US, for most trees, would probably work very well here.

Of course it is still true that if you talk to 10 people about soil mix you will get 10 different answers. And, soil is not the only variable in this, over time you begin to look at everything.

Bob

I give up. I'm not talking about a discussion about a recipe - I'm talking about soil science, which includes all soils yet no one soil in particular.

Al

Well, in fact, I wasn't talking about the recipe either, but as headcutter said, the whole nature of soil controversy in bonsai. However, if I hit the wrong nerve, I'm very sorry, because I have respected your knowledge of bonsai for ages. I just wanted really, to throw in the possible differences of opinion on water tables, but apparently that didn't get across. So again, sorry, but that's all I can say.

No problem. ;o) I wasn't trying to promote a recipe, just join in the discussion about soils in general. The science involved with soil chemistry and physics is pretty well settled, so there's not much wiggle room there, and you're right, of course, in your assessment that contrasts in opinion center more around recipes than science, but there are still lots of generalities that can be discussed w/o focusing on a particular soil.

No reply from the OP is some indication that he's happy with his answers or he's moved on, so I'll do the same.

Take care, L.

Al

I can't access this page:

www.evergreengardenworks.com/earthpot.html

Josh

Use link below, Josh. You're familiar enough with what I've shared about soil science to quickly see there's nothing there that conflicts with anything I've been saying for many years.

Al

Here is a link that might be useful: Try me!

However Al, the article is stating everything about soil in a purely black and white manner. As we all know there are a lot of gray areas in life. I will admit that it is a good starting point in understanding soil/water.

Bob

The thread I linked to has been active for more than 5 years and has about 1,500 posts to it. I've been babysitting it for the entire time it's been active. The same thread is posted at a competing forum site (starts with a "D") for less time, and the site is much smaller than GW, but it's still received around 38,000 hits. I can't even guess at how many hits the post at GW has received, but it is certainly well over 100,000. Not long ago, a man who had read it contacted me from Paris, France (what would be our equivalent of Parks and Recreation) for help, and we worked together to develop a soil from locally available ingredients for their containerized street tree plantings. More people than I can count have contacted me for soil help, some professional growers, and so far, no one has been anything but very happy with the fruits of our intercourse.

The science IS black and white. Let me back up a little - the physical part is pretty cut and dried as a conversational topic, but soil chemistry has many more facets, therefore, is more difficult to talk about with as high a degree of certainty. Still, there are plenty of aspects of soil chemistry that can be considered settled science, based not on opinion, but on what is currently known.

The gray areas primarily come to play when we start talking about methods of application and ingredients, but there are a lot of generalities that are not widely understood in both the physics and chemistry of soil science that when brought out in a discussion would yield enlightenment for more than a few.

Al

Y'all,

I now know more about soil characteristics than before I read this thread series. I am more encouraged about trying my hand at creating a better soil after reading the why, what and how, thus my own Bonsai Baby's experimentation starts from a higher level of understanding. Thanks to you all. Aloha

Now that I've read the article, I don't see any disagreement with the principles that Al's put forth.

In the article, the author refers to a water column...which is another term for "perched water table."

Josh

Yes, while the science and chemistry remain the same for the soil(s), everything else we do changes it. This is where all of the gray areas come into play. And, this is where it takes work, thought and sometimes trial and error to find the right combination which works for you.

Bob

A basic knowledge of the principles of soil chemistry and physics goes a long way toward almost completely eliminating the guesswork and trial and error approach. Knowing how soils work, and an understanding of how ingredients' physical and chemical properties relate to each other, AND the soil composition as a whole, allows the knowledgeable grower wide latitudes in determining what would be appropriate for a much more expansive array of circumstances/situations/conditions. Moving forward with decisions based on the solid underpinnings of sound science would find us working, thinking, and fumbling around trying different things with considerably more irregularity than those relying on the guesswork of trial and error.

Work smarter, not harder.color>size>

Al