Michael’s Soil Tips

Michael  is the owner and founder of the Los Lunas based Soil Secrets, and is a master of soil composition. Here are four surprising proclamations to consider:

  1. Liquid fish fertilizer is bad because of chemical additions used to make it “safe”
  2. Mushroom compost is bad because of its calcium-producing tendencies.
  3. Chemical acidifiers are bad because they create more salinity.
  4. Overusing compost is bad because it tends to boost PH.

There were numerous others which I don’t remember. I AM NOT suggesting that we immediately throw everything away and obey the gospel of St. Michael, and yet…  Michael magic potions are available from his nursery, as well as his potting soil for $7.00 a bag.

Fertilizer Basics

The 3 basic components of plant food are Nitrogen, Phosphorus, and Potassium. On all store-bought fertilizers, these 3 will be listed by the N-P-K ratios. Numerous other “trace elements” are blended with these. The compositions, strengths, frequencies of use, and seasonal timing provide yet more tempests-in-teapots for bonsaists to argue about.

Historical perspective: The use of organics is a very long-standing tradition for bonsai, in large part because commercial chemical production is a fairly recent invention. Nearly all old bonsai books advocate a mixture of organics blended together into a kind of dough and placed as small “cakes” on the surface of the pots. One of my earliest duties as a bonsai apprentice was to mix cottonseed meal, blood meal, and bone meal together, using ordinary baking flour as a binder, into a doughy,”earlobe texture” blend, then rolling it into long sausages and slicing it into little pucks. I would let these dry, then put one  puck into each corner of the bonsai pot.

There were several problems with this method. Generally, the bone meal as sold in bags was not really very water soluble. As the little cakes melted away, the bone would just lie there. Also, the blood meal was irresistibly attractive to dogs, mice, rats, squirrels, etc. A larger dog would pull pots off shelves to get at it, and smaller dogs would tear into bags and root around in it. If the cakes became rehydrated in the pots, they would soon become fly breeders of epic proportion. The relative ease of fish emulsion was a tempting substitute, or at least an alternating regime, and was/is widely used.

In recent years, commercial compositions have made huge inroads into the sacred organic methods. There are as many preferences as there are individuals. Some of us are high nitrogen advocates. Though this undoubtedly builds strength, it has several drawbacks. N encourages large, rank leaf growth, and long internodes (the length of the branch between leaves). As you veggie growers know, it will also hinder fruit and flower production. In Japan, it is also thought to make bonsai somewhat “course,” which essentially means lack of refined miniaturization on trunks and branches.

Many of us have been going over to high phosphorus blends. The first real advocate for this in the early 70’s was Warren Hill, whom some of you have met. He wrote an article in the yearly California Bonsai Society magazine called ” Phosphorus—The Key to Life and Beauty,” that influenced a lot of us. High P has long been advocated as a Fall food because it strengthens roots for the dormancy period. The iconoclastic Hill wondered why it shouldn’t be used all year.

Much voodoo surrounds the feeding process, which is far more straight-forward chemistry than we’d like to admit. The difference between the holy organics and Miracle Grow, etc. is probably not that significant. I have come to believe that seasonal timing is far more important than we realize here in the desert. Our growth cycles are heavily influenced by changes of light and temperature, and occur in a sort of punctuated equilibrium rather than in a slow, steady pace as in other climates. We get a dramatic, early spring flush, followed by a period of near dormancy during our hottest weather, then another flush as the trees anticipate fall.

I noticed today that my elms have suddenly come back to fast growth now that coolness is in the air. My new method, therefore, is to hit everything pretty hard in early spring with my beloved Tiger Bloom (2-8-4), in 7 day intervals or even more frequently. Then, from June through July I back off and let the trees consolidate their gains. In late August, I start cranking the food again to anticipate the fall, pre-dormancy flush. Some of you even feed through dormancy in reduced amounts, and I’m liking that idea better all the time. Getting those nutrients available before the growth actually begins seems important, as if the tree were pulling strength together for its big spurt.


John’s Soil Musings

“Studying wine taught me that there was a very big difference between soil and dirt: dirt is to soil what zombies are to humans. Soil is full of life, while dirt is devoid of it.” —Olivier Magny: Into Wine: An Invitation to Pleasure

There is probably more opinion/voodoo concerning soil than about anything else in bonsai, and that’s saying something! Nearly every devotee of little trees has a formula which that person asserts is the only mixture that can successfully grow a bonsai; basically, that “My dirt is soil, and your soil is dirt.” I want to give you a little history of the thinking and practice of bonsai mixes, and summarize my most recent experiences.

The original mix used in the US before and after WWII was; 1/3 sandy loam, 1/3 decomposed granite, and 1/3 humus, usually in the form of rotted fir bark which was then available in bags called forest humus. For the Komai Bonsai Nursery, we got the loam from Khan’s cousin who shared the nursery grounds with a small indoor plant wholesale business. Hiro made his soil from some excellent topsoil mixed with various humus components, and a good shot of sand. The granite was obtained by your Humble Narrator, who would take the ancient yellow truck and an assortment of little dogs up into Santa Anita canyon above Arcadia, CA, and scrape the beautiful stuff off the road cuts into trash cans, which then had to be screened of dust at the nursery. We had three big cans of ingredients in the workshop, and we’d mix by upping the granite for conifers, or upping the humus for deciduous, plus the “house mix” of 1/3 ea. for our classes.

I also would take a load of the glorious granite down to John Naka’a house periodically. He used the same basic mix, but substituted oak leaf mold for humus. In the early 70’s, a group of Japanese heavyweights came to LA to demonstrate, took a look at Khan’s soil mix, and rejected it out of hand. To Khan’s astonishment—and testing his cultural need to be a gracious host—the demonstrators went into our large pot room, took about 20 cheaper pots off the shelf, and began breaking them up into small pieces, which became their soil mix with no additions! This was our first exposure to akadama, and it aged Khan about 10 years in an afternoon.

The writing was on the wall. Khan found a source of horticultural pumice in bags that we began experimenting with, since we couldn’t dig decomposed granite fast enough to keep up with demand. When Harry Hirao came up to teach his monthly class, he took one look at the pumice, and bought a few bags, into which he began transplanting his collected California junipers. His success rate improved dramatically, and the era of non-organic soil mixes had begun in earnest. The only thing Khan ever sold in quantities sufficient to justify his hopes for the nursery as a “business” was hundreds of bags of pumice. Though we kept a supply of house mix soil for the beginners’ classes, the more advanced people quickly went to pumice at 100%, or nearly so.

When I came to Socorro, I kept the same loose mix I used in Capitan (elev. 6,500 feet), and immediately started having trouble. I jerked stuff out of the gravel and went, in many cases, out of laziness and not having any “grit” that I liked, to 100% Miracle Grow potting soil, and things improved. In fact, my congenital laziness seemed to be working well.

My current opinion that this eternal fussing over soil mix is yet another fetish, and that other factors are more significant than we imagine. My current practice is to have a series of bags lined-up as follows:

  1. Green label Miracle Grow potting mix,
  2. Playground sand, which is a little finer than I’d like, but beware “bedding sand” which is dangerous to both kids and trees,
  3. Horticultural pumice, which I’ve been buying by the pricey bag at Rheem– we need to make another pick-up run to Espanola,
  4. Well-rotted humus other than that mushroom compost crap which, like most manure-based stuff is pretty salty, and a few other humus products for experimentation.

I use my Dr. Fox coffee-can scoop, and add stuff as I feel right about it. I also keep a bag of pea gravel for a thin layer over the screen when repotting, mainly out of old habit.

This grit business has led us down many strange paths, and everything from Grape Nuts to kidney stones has been tried. I still love decomposed granite, and we can collect it here, but pumice has a bit of moisture retaining porosity that works best for us. It looks a little bird-poop white on newly potted trees. Several things have NOT worked for me. I’ve come to detest any kind of cat litter or grease sweep, though I see it recommended by bonsai people. Many of you have gone to buying Japanese dirt in the form of akadama, and I would recommend the high-fired variety. The unfired stuff breaks down too fast for my taste. I don’t like Turface anymore, some of the Oregon Mafia have railed against it as too moisture-holding, but we’re a long ways from Oregon, Toto. I just don’t care for it. I’m settled now on pumice, it’s the best thing we’ve got, I believe, and it’s readily available.

Now, what about this dirt vs. soil issue? I think we have not given anywhere NEAR enough consideration to the fact that our mix must become a happy little land, chemically and organically. As you know, when I first heard our boy Mike Melendrez in Las Lunas talk about this, I wanted to have his baby immediately. In retrospect, I may have gone overboard on my worship, like a little girl who gets hung-up on horses. But, it confirmed some ideas which I was not educated enough to articulate. And, many of us have been using his Soil Secrets black goo-goo, and we think we’re seeing good things happening. Fortunately, we have some members who are expert on these matters, and we need to force them to tell us all they know, using violence if necessary. Our soil needs to be seen as a living organism, too, using its constituent physical structure to nurture life, and to hospitably sustain it. Think about this, and we’ll discuss it more in the coming months.


Enemies of Bonsai

The main enemies to keeping bonsai alive in New Mexico are:

  1. Direct and reflected full sun.
  2. Desiccating winds, both summer and winter.
  3. Lack of any meaningful humidity.

There are a few others, like poor (alkaline) water, and extreme temperature variations, often occurring in the same 24 hour period.

Very few plants can handle a full day of Albuquerque summer sun, especially in the afternoon, and especially reflected from walls or fences. You must provide some sort of shade mechanism from about 10:30 am onward, and it needs to be pretty damn thorough. Some of our folks have sufficient large tree growth in their yards to provide dappled sun all day, and it works for them. Most of us require some sort of structure or shade cloth moorings to get the job done. My first effort in Socorro involved wood lattice over a ramada. It did not provide nearly enough protection, and the wood eventually deteriorated from the elements. This year, junior and I got serious and recovered the frame with 90% filter shade cloth, and the difference was huge. Everything we have, including the toughest junipers, are enjoying a far less stressful environment. I have also blocked the S. Western exposure with a new plum tree that really helps, as well. The problem is that a lot of shade cloth is truly ugly, especially in black. I like the looks of those sail-shaped babies though, and they provide an opportunity to create something actually quite beautiful. The cheapest stuff is available at Harbor Freight, they call them “mesh tarps.” I’d suggest doubling them if they’re in full sun. Amazon also has an extensive selection. Some of you have had good success keeping trees on east and north-facing walls which block both sun and wind.

The problem of wind is difficult to solve. I’m currently having decent luck with a layer of bamboo screening mounted against a chain link fence— it’s held up amazingly well for some years, considering the fact it gets a full summer blast from the south. You’re going to have to be creative about this, or it’ll drive you back to your old hobbies of Green Stamp collecting and Zoophilia. I have in the past allowed enough surplus hangover of shade cloth to create a wind block, and have had mixed success. Much of this requires some serious thought as to siting…. best to get it right the first time if you can.

The issue of water is simple to grasp but hard to fix. Nearly all trees do much of their survival work through their leaves and foliage, of course. In our climate, with humidity usually pushing zero, trees need to hunker down for long periods between rains, and wait for the merciful monsoons to get them going again. So, we have the curious phenomena of summer dormancies, and such. I would guess that 80% of all lost bonsai die from water issues. With our coarse soil mixes, it is virtually impossible to over-water outdoor bonsai in ABQ, and I am always terminally skeptical when any of us claims over-watering to be a problem here. So, our trees need copious water both in roots and on foliage. When I water in 95 deg. weather, I soak down everything—- benches, ground, structures, surrounding trees and shrubs, even shade cloth. I have had endless trouble with automatic watering systems, so I don’t really trust them, but I bought a ton of misting- system stuff and would like to see how it works. Do any of you use misters?? Watering is taken with extreme seriousness in Japan—it takes at least a year for apprentices to be trusted with the task. When we are at Queen Connie’s, that is one of the things you all should learn from her—she is a Maniac Master of watering.


— John

Leaf Anatomy

Presentation by our resident botanist Karl Horak.
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Transcript of Leaf Anatomy
Leaf Anatomy
for Bonsai
It’s all about photosynthesis
But what exactly is a leaf?
Evolutionarily, it’s a flattened stem
The key is to look for an axillary bud
What the hell is an axillary bud?
It’s a bud in an axil, of course.
Damn you, botanists… what the hell is an axil?
CO + H O + Light
Carbohydrates + O
CO in and O out,
but also H O out
The arrangement of leaves is controlled by auxins and other growth hormones
For bonsai, this is critical because…

That’s where the axillary buds are
and they control the appearance
of secondary branches

And e-vile botanists have
come up with all sorts of
terminology to describe
the results
All these variations are adaptations to deal with photosynthesis: conserve water, absorb light, exchange gases, protect from herbivores, resist disease, etc.
For bonsai, small leaves have the proper scale to
give the desired esthetic effect:
Juniper scales
Short-needled pines
Microphyllous leaves
Compound leaves w/small leaflets
Leaves amenable to size reduction
Lucky for us, leaves are very plastic.
Since they don’t have much to do with
reproduction, they can vary to suit changing
conditions (sun vs shade, wet vs dry, juvenile
vs maturity).

Phyllotaxy is the arrangement of leaves on the stem, usually in a spiral
Except for adventious buds, aka “breaking back”


Many of you will recall that in January of 2013, there was a crisis for the Bonsai community as the U.S. Department of Agriculture had placed a ban on the import of Akadama soil into the United States. Akadama is a basic ingredient in many soil compositions used throughout the Bonsai community. As it turned out, the ban was only temporary, but Triple Red Line Brand was permanently restricted. However, this resolution took several months (the government does move slowly at times). After some extensive searching and through the contacts of Roger Case, as a club we were able to place an order with a California operation which still had a supply of Akadama which had been received before the ban took effect.

Unsure of what the future for Akadama might be, and after talking with many of the local west coast Bonsai professionals, I determined to see if there were any materials available which had similar properties to Akadama but were native to the U.S. and would meet the requirements for a “good” Bonsai soil. Most sources of commercially prepared soils, bonsai enthusiast and bonsai professionals agree that a “good” bonsai soil will have the following characteristics:

  1. The soil composition must drain excess water quickly while retaining sufficient amounts to support the tree after watering.
  2. The soil composition must be non-compacting and provide space for oxygen exchange.
  3. Whether a single component or multiple components are used in the soil composition, they must be of a uniform size.
  4. The composition should have a neutral or near neutral “ph” factor (somewhere between 6.5 and 7.5 “ph”).
  5. The soil components should have a good “Cation Exchange Capacity” [CEC].

All of the other basic components (red and black lava rock, pumice, charcoal, and granite grit) for what is commonly referred to as “Boon Mix” continued to be readily available. The component needing a comparable replacement was the Akadama.

CATION EXCHANGE CAPACITY (CEC) is measurement of a soils capacity to retain nutrients. Clay (Akadama in this case) and organic matter have negative electrical charge These negatively charged soil particles will attract and hold positively charged particles (in the fertilizer you apply) much like opposite poles of magnets will attract

Elements having an electrical charge are called ions. Positively charged ions are called CATIONS and negatively charge ions are called ANIONS. [Cation is pronounced cat-eye-on; Anion (negative charges) is pronounced ann-eye-on].

Clay ions are always negatively charged and are therefore identified as ANIONS. Organic particles of soil may have either a positive or a negative electrical charge and can therefore be either a CATION or an ANION. CATIONS held on either clay or organic particles of soil can be replaced by other CATIONS, thus they are EXCHANGABLE.

The total number of CATIONS a soil can hold – or its total negative charge- is the soil’s CATION EXCHANGE CAPACITY. The higher the CEC, the higher the negative charge of the soil and the more CATIONS it can hold. The higher the CEC levels, the more fertile the soil.

The fact that CATIONS can be exchanged in the soil is the key factor in Bonsai plant health. The exchange factor allows for the positively charged nutrients to be ADSORBED onto the negatively charge clay or organic soil particles and then later released for ABSORPTION by the feeder roots of the plant as needed. ADSORB means that the positively charged nutrients attach to or cling to (think of static cling from the dryer) the negatively charged soil particles. The nutrients do not penetrate the surface of the soil particles, they simply cling to the surface until released or exchanged for other ions. Without the effect of CATION EXCHANGE CAPACITY, nutrients applied to the soil would simply wash out with the drainage of the applied water.

The CATION EXCHANGE CAPACITY scale ranges from a 1 (lowest level) to 100 (highest level) based on the type of soil and the “ph”. Sand has a CEC of 5 – 20; Clay has a CEC of 20 – 50; and organic soil has a CEC of 50 – 100. Depending on the particular lab reports, Akadama soil was identified as having a CEC of between 21 and 26.

So, if we need to find a replacement at sometime for Akadama in out mix, in order to meet the characteristics of a “good” Bonsai soil, we need an inert ingredient which has a neutral, or near neutral, “ph” and a CEC of between 20 and 30. In my research, I found 3 such soil components which I decided to use as part of the soil study and one “organic” based soil.

“Boon Mix” was used as a control and has a CEC value of 23. Wee Tree bonsai soil mix, which was screened for fines and then supplemented by additional lava rock, pumice, charcoal and granite grit, was included as it is close to an organic mix for CEC purposes, and after screening and supplementing it has a CEC value of 28. Diatomaceous Earth (DE) has a CEC value of 27, Haydite which has a CEC of 25, and Turface (MVP) with a CEC value of 30 were the other 3 soil components selected as having a neutral or near neutral “ph” and a CEC values within the 20 to 30 range. These soil components were mixed with lava rock, pumice, charcoal and granite grit in the “Boon Mix” proportions except for the Turface.

Turface came with a manufacture’s caution that in horticultural applications, the volume of the Turface in the soil composition should not exceed 10% to 15% due to a risk of the soil becoming nutrient toxic. It was therefore mixed at a ratio of 10%.

Once the soils were selected and prepared, they were all tested (measured) for Soil Permeability and Soil Porosity.

PERMEABILITY (sometimes referred to as Hydraulic Conductivity) is a measure of the ease with which fluids (mainly water) will flow through or be transmitted by a porous rock, sediment or soil. The packing (compression), shape, and sorting of granular material controls their permeability. Permeability is controlled by the size of the particles of the sample soil, the consistency of the size of the particles, the size of the pores or void between the particles and the degree to which the pores or voids are interconnected. Generally, materials of larger particle size which are consistently sorted will be more permeable.
POROSITY is a measure of the open spaces (voids) or pores found within a particular soil or sediment. The open space in a soil sample is comprised of the open spaces between the particles themselves and within the cracks, crevices, or cavities between or on the soil particles themselves. Porosity determines the total amount of water a soil or sediment will hold. Porosity is largely influenced by factors of particle size, shape and assortment. The greater the column of pore spaces a material contains, the higher its porosity and the more water it can hold. Porosity is expressed as a fraction or a percentage of the volume of the pore space to the total volume of the material.


TOTAL POROSITY — The amount of water accepted by the measured amount of soil mix. (In this example the amount of soil is 8.5 ounces.)

SOIL POROSITY — Amount of water retained in soil mix sample after draining. This is the amount of water in the soil which will be available to the plant. Not all of the retained water is available to be used by the plant due to being absorbed within the particles of the soil and due to the effects of the surface tension of water.

PERCENTAGE OF AIR IN SOIL — Air filled space within the soil sample after drainage from initial TOTAL POROSITY stage.

HOW TO MEASURE — For our example the initial volume of soil is 8.5 ounces.

TOTAL POROSITY is the amount of water that is accepted by the soil sample to reach total saturation.

Record this number. (For example if the soil sample accepts 6 ounces of water to reach total saturation, record 6 ounces. Allow the soil sample to stand covered in the water for 30 minutes.)
SOIL POROSITY — The amount of water remaining in the soil sample after drainage from the original TOTAL PROSITY amount of water. (For example, the amount of water that drains from the soil sample equals 2.5 ounces. Subtracting 2.5 oz. from 6 oz. means that 3.5 oz. remains within the soil sample. Record3.5 oz.)

PERCENTAGE OF AIR IN SOIL SAMPLE — The percentage of air remaining in the soil sample is equal to the amount of drainage water collected. (In our example this was 2.5 oz. Record this number)
To determine the TOTAL POROSITY, SOIL POROSITY, AND PERCENTAGE OF AIR in the soil sample divide each recorded number by 8.5 and then multiply the result by 100.

TOTAL POROSITY = 6.0 divided by 8.5 = .70 — .70 x 100 = 70.5. The TOTAL POROSITY in the example is 70.5 percent.
SOIL POROSITY = 3.5 divided by 8.5 =0.41. — .41 x 100 = 41. SOIL POROSITY in the example is 41 percent.

PERCENTAGE OF AIR IN THE SOIL SAMPLE = 2.5 divided by 8.5 = .29. — .29 x 100 = 29. PERCENTAGE OF AIR in the example is 29 percent.
I then determined that in order to conduct as fair an analysis of the 5 soil mixes as possible, I would select 5 of the most popular trees grown for Bonsai, obtain 5 of each species of tree (all were one year old cuttings or seedlings) and plant one of each tree in the five soil mixes. The trees that were selected were Japanese Black Pine, Korean Hornbeam, Japanese Larch, Trident Maple and Shimpaku Juniper. All of the trees were planted in the first week of March, 2013.

2013 Progress, Outcomes and Observations — All 25 trees were planted in 4 inch nursery pots the first week in March, 2013. There was one of each species of tree planted in each of the 5 soil compositions. After planting, the trees were placed in a protected area of my un-heated green house were they would get plenty of light. In mid May, they were given their first fertilization which was comprised of 20-20-20 mixed at 1/4 strength combined with fish emulsion and kelp meal at 1/2 strength. This feeding formula was repeated every 14 days for the remainder of the growing season.

All of the trees appeared to prosper until about mid July when it became apparent that the 5 trees growing in the Turface MVP mix were not as healthy as the other trees. By early September two of the trees growing in the Turface mix had died and the other 3 were definitely weaker than the other 20 trees. A careful unpotting of the 2 trees which had died revealed that the problem was the Turface mix remained too wet and the roots had rotted. Remember, the Turface composition was only 10% Turface. I immediately reduced the amount of water the other 3 trees in the Turface soil mix were getting.

All of the other 20 trees in the other 4 soil mixed grew tremendously. By late October, the maples, hornbeam and larch had all grown more than 2 feet in height. After their leaves and needles had turned, they were all lightly branch trimmed and reduced in height to approximately 15 inches. The black pine and juniper had extended approximately 2 to 3 inches. The real surprised to me was that the roots (on these 20 trees) had completely filled the 4 inch pots and grown out through the drainage holes and several inches into the gravel floor of my greenhouse. All would need to be repotted in late winter of 2014.

One observation that I made when lifting the trees out of the gravel floor was that there was tremendous growth of feeder roots on the roots that had extended into the gravel. The roots extending outside the pots were trimmed off. I therefore had expectations that the pots would be full of strong feeder roots when I repotted.

2014 Progress, Outcomes and Observations — In late February, all of the trees were showing signs of bud swell and so repotting was in order. Remembering the tremendous feeder root growth in the gravel floor of my greenhouse, I was slightly disappointed when I commenced repotting. While the 4 inch pots were quite full of strong roots, they were long and fibrous, but not nearly as dense with feeder roots as I anticipated.

The soil around the root ball and under the root ball was lightly loosened with a few strokes from a chopstick on all of the trees. All of the trees were repotted into 6 inch bulb pots and additional amounts of the appropriate soil compositions were added.

The 3 remaining trees in the Turface composition were still weak, and their roots did not fill the 4 inch pots as with the other 20 trees. As the roots were only in the top 1/3 of the pot, I determined to apply a small amount of rooting hormone to the root balls and to increase the particle size of the soil mix to 1/4 inch and to increase the pot size to 6 inches as with all of the other trees. I also determined to reduce the watering routine for these 3 trees so as to hopefully promote a drier soil.

Once all of the trees had been repotted, they were again returned to the greenhouse for the new season. The fertilization routine for 2014 was the same as it was in 2013. Again, all of the trees displayed tremendous growth. The 3 trees in the Turface mix responded favorably to the change in the soil size of the mix, although they did not show the progress of the other trees in the other mixes. Again, for the other 20 trees, the roots filled the six inch pots and grew into the gravel floor of the greenhouse.

In late October, as the trees were being prepared for the winter, I saved some of the feeder root masses growing in the gravel of the greenhouse floor. Over the winter I wanted to study these. I also took a slight risk and lifted the strongest tree in each soil mix and collected a root to also study over the winter. Clearly, all of the trees will need to be repotted in the late winter of 2015 and will move up into 8 inch bulb pots.

Late 2014 and Early 2015 observations. At this point, I feel comfortable in saying that I would most definitely never use Turface in any soil mix for Bonsai again. Turface simply retains too much water. Even after changing the size of the soil mix in 2014, the 3 trees do not show the health and vigor of any of the other 4 compositions. It also appears to decompose or degrade into sludge rather fast. The original soil mix which was left on in the transplant of 2014 now has very little granular structure left. I will know more when I look at the trees during repotting in a few months.

Of the 4 other compositions of mix that I have evaluated in this study, they all appear to support the development and growth of the trees and the root systems. Clearly, the CEC value of the various soil compositions was favorable to the trees, and with the exception of Turface would appear to satisfy the quest for a “good” Bonsai soil.

When I took the root samples I had collected when I lifted the trees to a Master Gardener office and did some examination under a microscope, there were some obvious differences in the root development. The first thing I noticed was that while there were soil particles clinging to the roots in all of the samples, only in the Akadama mix did the root actually penetrate through the soil particle and emerge out the other side. The root actually impaled the soil particle. A close look at a dry Akadama particle revealed that there are tubular structures within the Akadama particle which in many cases actually traverse the entire particle. Therefore, these particles will cling to the root until they decompose or until the root expands to the extent that the root fractures the particle. All of the other mixes revealed that the roots were growing only in or through surface irregularities and crevices of the composition particles.

Additionally, a microscopic examination of the feeder root clusters growing into the gravel of the greenhouse floor showed that these roots had multiple divisions of the roots where they had pushed against sharp edges of the gravel. But why were these roots so much healthier than the roots in the pots? A friend at the OSU agriculture labs asked me to bring the root samples in to him along with samples of the various soil mixes and a bucket of the greenhouse gravel. After putting the roots under the microscope, he and I sieved the 2 gallons of greenhouse grave.

Although the gravel in my greenhouse was rated as 1/4 inch minus in size, what we found was that the particle size of the mix was actually (according to the sample) approximately 20% in the 1/4 to 1/2 inch minus size. It was this additional size of particle in the mix which accounted for the healthier root development. There was more oxygen in the gravel mix in the greenhouse than there was in the uniform size of particles in the pots. This mix of larger sized particles provided more space for oxygen to collect as the water drained down. Roots need water, oxygen and nutrients to develop. The additional oxygen spaces were key.

I intend to test this concept with the next repotting. I have sufficient screened components of each of the soil mixes available that I will be able to add 20% of soil volume in the 1/4 to 1/2 inch size and incorporate that throughout the soil mix in the larger 8 inch pots. If the concept proves positive, I expect that during repotting in 2016 I will find significantly more of the feeder roots throughout the root mass inside the pots.

So the take away from 2 years of this study is:

  1. Akadama is still probably the best soil mix component of all of the ones tested.
  2. Akadama will allow the tree roots to literally penetrate right through it.
  3. It is possible to control (raise or lower) soil porosity by changing the percentage of each component in the mix, therefore you must test the porosity of each component as well as the porosity of the final mix.
  4. Soils with similar CEC values will provide excellent root development and trees growth very similar to Akadama although Akadama has some clear advantages.
  5. Better root development appears to be possible with soil mixes containing a combination of similar sized particles as opposed to a single uniform size.

So there you are. Two years worth of observations and study. Have a great new year and remember, spring is coming so get your repotting materials, tools and your plan ready.

—Keith Wingfield

Bonsai Botany

Presentation by our resident botanist Karl Horak.
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Plant Anatomy for Bonsai
What is Plant Anatomy?
The internal structure of plants
A Bonsai-centric Overview
Ancient visage
Secondary Growth
Girth only
Primary Growth
Shoot apices
Anatomy is a key to grafting, air layering, rooting of cuttings, “breaking back”
Not to be confused with “Plant Morphology”
The external structure of plants
Usually studied by means of examining thin sections under a microscope
Concentrating here on woody dicots and gymnosperms
Aesthetic form
Longevity and health
Secondary growth
Keiseiso (cambium)
Za & nebari
Jin & shari
Primary growth
Apical meristems
Phyllotaxy & leaf anatomy
Growth hormones
Root structure
Growth hormones
Tsugiki (grafting)
Toriki (air layering)
Sashiki (cuttings)
Fruits and seeds
And why should I care?
Root apices
Occurs at apices
Intimately related to plant physiology
We’ll save leaf anatomy, photosynthesis, and the whole water balance question until later.
Plus ethylene and abscisic acid, among others
Create a complex set of gradients that control growth and differentiation
Final Words

Plant anatomy involves a lot of strange vocabulary that describes the strange goings-on inside of plants. In the end, understanding the internal structure of our trees makes us better able to produce the living works of art that are Bonsai. From leaf size and shape to branch angles to bark texture, the underlying cellular structure informs the trees that we work with.

Bonsai in March

This is a tricky month. The average high temperature is 59 degrees, and the average low is 32 degrees. The record high is 85 degrees and record low 9 degrees. The average humidity is 38%. The winds are picking up, and we can get very strong gusts. Winds have been clocked at 60 MPH. Keep the trees in the cold frame until the end of the month unless you are repotting, and then return them to cold frame by nightfall. Open cold frame two weeks before bringing out trees.

Watering: Trees in the cold frame will not need much water, but do not let them dry out. Keep slightly damp. One time during the month, water with mild solution of MirAcid again. The trees planted in the ground will need more water; probably once a week , depending on winds. The winds will dry out the soil very rapidly. Water in the morning.

Fertilizing: Start adding some nitrogen in weak solutions. Use some phosphorus for flowering and fruit trees.

Spraying: Spray with dormant spray up to the time deciduous trees are budding. Discontinue after buds appear and control insects with other products. Watch for black aphids now. Check just beneath soil level at base of trunks on fruit and flowering trees for borers. Use borer crystals immediately.

Trimming & Pruning: Prune out winter damage as soon as it can be determined what is alive. Seal cuts not only to keep sap in, but to keep infection out. Save scions for mid-April grafting. Keep in damp paper towels in refrigerator.

Repotting: If buds have appeared on deciduous trees, repot now before the leaves open and before the plant flowers. Evergreens can wait as long as the end of May. If repotted last year, they may not need it this year. This depends entirely on the growth pattern of the species. Place the newly repotted trees back in the cold frame until the first part of April.

Bonsai in February

The last month of the calendar winter. The weather is similar to January. The nights will still be below freezing. Toward the end of the month, there are some warm, balmy, spring days. Close the cold frame or the trees get too warm and start budding. The average high for the month is 52 degrees; average low is 27 degrees. The record high is 75 degrees and record low -6 degrees. Relative humidity around 48%.

Watering: As in January, DO NOT allow the bonsai to dry out. Dormant trees in a cold frame do not use much water. Every ten days to two weeks should be enough, but check every week to be sure. Water trees planted in the ground once a week to ten days when the dirt has thawed, usually around noon. DO NOT water frozen bonsai.  Toward end of month on warm days the planted trees may need more frequent watering.

Fertilizing: Once during the month add small amount of MirAcid to the water again and a weak solution (2 recommended) of 5-50-17 fertilizer. No nitrogen yet.

Spraying: Not necessary.

Repotting: At end of month, the warm weather may have started the Japanese Maples and other deciduous trees to swell before budding. If they need repotting this year, do it before the buds open. Put them back in the cold frame after repotting. Prepare soil mixtures for repotting the next two months. If you use any garden dirt, bake it at 150N for 1 hour to kill snail eggs, pill bugs, and weed seeds. Soil mixtures may be found in Naka’s Bonsai Techniques I. Add a bit more peat moss to hold water in our drier climate.


Bonsai in January

This is our middle of winter, and it can get cold. The average high temperature is 46 degrees; the average low is 23 degrees. Records are 69 degrees for the high and -17 degrees for the low. Relative humidity is 53%. On warmer days of 40 degrees or above, the cold frame can be opened to allow circulation of fresh air. Also, a wet snow does them good, but close the cold frame before nightfall.

Watering: Albuquerque’s climate is predominately in Zone 10 and considered high desert which is hot daytime temperatures and cool to very cold nights. The low relative humidity, high altitude, and high winds contribute to the desiccation of container grown trees. DO NOT allow the bonsai to dry out even in winter. Dormant trees in a cold frame do not use much water. Every ten days to two weeks should be enough, but check every week to be sure. Water trees planted in the ground once a week to ten days when the dirt has thawed, usually around noon. DO NOT water frozen bonsai.

Fertilizing: This is a good month to apply a light (2 strength) solution of MirAcid to neutralize the alkaline soil and watering done from the city tap. The “sitting” water barrel is now frozen and inaccessible. Apply fertilizer or any chemical to moist soil to prevent root damage.

Spraying: Dormant spray both in cold frame and in ground if the temperatures are not too severely cold outside. Bonsai may be brought indoors for display for a short period of time, but place them in the coolest place available.

Helpful Equipment: 2 whiskey barrel to let water sit and add conditioners small rose watering can quart sized zip lock bags for soil mixtures

Bonsai in December

This is winter now. Even though some days are fairly warm, keep the cold frame closed. Open it if there is a “warm” snow during the day, but close by nightfall. The average high temperature is 47 degrees; the average low is 24 degrees. The record high is 72 degrees; 3 degrees is the record low.

2015-16 update:  El Nino forecasts from NOAA are showing above normal precipitation with normal or slightly above normal seasonal temperatures.

Watering:  Water less from now to February, but never let them dry out completely. Trees in a cold frame stay damp longer than those in the ground, and they are not using very much water when they are dormant. Never water trees when they are frozen. Water in the morning so all water can drain from the pots by evening. Water trees in the ground at mid-day about once a week. The ground stays damp under the straw. Check for dryness by inserting your finger in the straw. If dry, water.  No fertilizing.


Bonsai in November

The nighttime temperatures are going below the freezing point now. The average high temperature is 57 degrees; the average low is 31 degrees. The record high is 77 degrees; the record low is -7 degrees. Trees should be dormant now and in their winter protection. You may open the cold frame on warmer days and during “warm” snows. Close the cold frame by sundown.

Watering: Water less from now to February, but never let them dry out completely. Trees in a cold frame stay damp longer than those in the ground, and they are not using very much water when they are dormant. Never water trees when they are frozen. Water in the morning so all water can drain from the pots by evening. Water trees in the ground at mid-day about once a week. The ground stays damp under the straw. Check for dryness by inserting your finger in the straw. If dry, water.

Fertilizer: None necessary.

Trimming & Pruning: Remove any leaves left on deciduous trees. Remove any extra long second year needles on pines. Time for second trimming on black pines. DO NOT ATTEMPT wiring this late in the year.

Repotting: DO NOT ATTEMPT to repot at this time.

Bonsai in October

Nights may be too cool now for semi-tropicals. Move deciduous trees to a shadier location to prevent new growth. Watch the weather reports more carefully now. It is common to have an early frost. The average high is 71 degrees; the average low is 44 degrees. The record high is 87 degrees (2015 update:  expecting 90° on Oct. 2); record low is 22 degrees. The relative humidity averages 43%.

Watering: You may cut back on water depending of the temperature, but do not let them dry out completely.

Fertilizing: Half normal feeding. No nitrogen.  (Check out John’s recent screed on fertilization.)

Trimming & Pruning: Trim strong growth on upper portions of conifers. Trim and clean off dead needles. After leaves have fallen from deciduous trees, it is safe to shorten the year’s growth. Clean all dead leaves from soil. At the end of the month, remove all fruit and any seed pods. The berries may be saved until spring if the tree is healthy. Trees may be rewired for winter.

Winter Care: Prepare the cold frame with snail baits and insecticides; purchase fresh straw. Prepare ground for those bonsai that will be planted for the winter. Leave the trees out as long as possible to insure they’re going dormant normally. Toward the end of the month, remove them from their pots without disturbing the roots any more than necessary and plant the trees in the prepared ground. Sprinkle pill bug bait generously and cover with straw. Those bonsai that are to be stored in the cold frame for the winter should remain in their pots.

Bonsai in September

Days are getting cooler but there are still hot days an it is still very dry (except during the state fair downpours!). The average high is 83 degrees; the average low is 56 degrees. The record high is 98 degrees; the record low is 32 degrees. If freezing weather is forecast, put the trees in the ground.

Watering: You may cut back on water depending of the temperature, but do not let them dry out completely.

Fertilizing: Half normal feeding. No nitrogen.  (Check out John’s recent screed on fertilization.)

Trimming & Pruning: Long shoots on new bonsai should not be cut off completely, but slightly trimmed and only after shoot has matured. Some trees will go through a last spurt of growth before going dormant. Remove any wire that is cutting in to bark.

Winter Care: A cold frame is recommended for winter storage of bonsai that need a dormant period. An alternative method of winter care is planting the tree directly in the ground after gently removing it from its bonsai pot. A cold frame should be built on the north side of a building.

Repotting: None.

Bonsai in August

There are usually thunderstorms during the first part of the month. They usually stop abruptly, and the end of the month can be the driest part of the year. The average high is 89 degrees; the average low is 63 degrees. The record high is 101 degrees; the record low is 52 degrees. The average relative humidity is 47%, but remember the higher humidities occur only during the first week or so. Keep rotating trees and checking for bugs, especially snails and slugs. A harder spray of water in the morning can wash some of these pests away.

Watering: Protect from gully-washer thundershowers, but don’t be fooled by a thin layer of damp surface soil. Water every day, twice toward the end of the month. Spray foliage–light misting often. No water late in the evening.

Fertilizing: Light mixtures. Cut back nitrogen and raise phosphorus.

Spraying: Keep bugs under control.

Trimming & Pruning: Be careful about any drastic pruning, especially on flowering trees. Check wires again. Remove any tight wires.

Repotting: DO NOT attempt any transplanting or repotting this late in the year.

Bonsai in July

The weather is still hot, but there is more rain. Average high is 92.2 degrees; average low is 65.2 degrees. The record high is 104 degrees; record low is 54 degrees. Relative humidity is 43%. Rains can come down in torrents. The sun filter overhead has another use, protecting the bonsai from having soil washed out of the pot.

Watering: Water well in the morning until it runs out of the bottom of the pot. Cut off any roots growing out of drainage holes. The deciduous trees will probably need more water in the early afternoon. Check pines and junipers for moisture. It is not advisable to water in the late evening because leaves are subject to mildew if they don’t dry off by nightfall. Remember to water the area around the trees.

Fertilizing: Continue small amounts regularly. Change types to get different trace elements. The fertilizer should still contain nitrogen.

Spraying: Control insects and check fruiting trees for borers. Borers attack the trunk just under the soil line and can kill a tree in just a few months.

Trimming & Pruning: Later this month, you can de-leaf if necessary. Do not do this every year. Keep the junipers pinched. Paint the hardened off, dry jinned areas with lime sulfur, and place the tree in full sun for a while. You can wire hardened off wood now. Remove most of the fruit so the tree can preserve some strength. See BCI Magazine, July/Aug 1987. Keep checking wires.

Bonsai in June

This month is traditionally hot and dry. Average high is 89.5 degrees; average low is 59.7 degrees. The record high is 105 degrees; the record low is 42 degrees. The humidity averages 29%, getting down to around 10% by afternoon on a windy day. It is important now that the trees are in filtered sun. If they have too much shade, the trees will put on spindly growth; with too much sun they will bake. Keep rotating trees during growing season.

Watering: Water well in the morning until it runs out of the bottom of the pot. Cut off any roots growing out of drainage holes. The deciduous trees will probably need more water in the early afternoon. Check pines and junipers for moisture. It is not advisable to water in the late evening because leaves are subject to mildew if they don’t dry off by nightfall. Remember to water the area around the trees.

Fertilizing: Continue normal light feeding.

Spraying: Only as necessary.

Trimming & Pruning: New shoots on older deciduous trees can be cut back now. Start pinching back cypress and junipers with fingers or tweezers. Cutting with shears turns the ends brown. Young pines and vigorously growing older pines should be de-candled. Start with the lower part of the tree first. Leave the top until later. Check all trees for wire cutting into the bark. If it is, remove immediately and rewire.

Bonsai in May

This month is still windy. Average high is 79.9 degrees; average low is 50.7 degrees. Record high is 98 degrees; record low is 28 degrees. Average humidity is 28%, lowering by 5 PM to 16%. Start a habit of rotating trees periodically to insure healthy growth all around.

Watering: Water well every morning, hosing entire area on windy days. Keep pines and junipers a little drier.

Fertilizing: No fertilizer at all for any trees just repotted. Wait four weeks before feeding them. Apply some bone meal to fruit and berry bonsai. Continue a regular program for the remainder of the trees, increasing nitrogen content. Change fertilizers periodically to pick up different trace elements.

Spraying: Keep checking for aphids, grasshoppers, spider mites, and white flies. Sometimes a small pinch of systemic insecticide should be added to pellet-type fertilizers.

Trimming & Pruning: Cut back long sprouts, leaving 2 or 3 buds. On older deciduous trees, shoots should be left on until they harden and stop growing. Remove these shoots the following dormant season. Start wiring again, not too tight. Don’t try to wire tiny new growth. The new candles on older pines should be pinched back, but leave the candles on young trees for another month. Do the jin now.

Repotting: Repot junipers and pines. When transplanting a pine, save a small amount of soil which has some white fungus. Mix it with new soil and place in bottom of pot. Pine and this fungus have a joint living relationship.

Bonsai in April

April is usually the windiest month in Albuquerque. The average high temperature is 70 degrees, and the average low is 41 degrees. The record high is 89 degrees; the record low is 18 degrees. Humidity averages 30%. Start bringing trees out of the cold frame, but be prepared to put them back in should there be a late killing frost. Protect them from wind. Deciduous trees have probably started new shoots and/or blooms by now and need filtered sunlight. Do not expose any bonsai to full sun yet. Albuquerque sun is very intense due to the mile high elevation and mostly clear days. As spring and summer progress, temperatures get hot. Bonsai require an overhead light filter–a large tree, mesh lath work, etc. Set the trees on benches or tables, not on the ground. If they stay on the ground very long, they collect snails and pill bugs. The former eat leaves, and the latter eat the roots. Pill bugs will also get in the post when they are in the cold frame. After watering, soak entire tree and pot in a mild solution of fungicide and insecticide.

Watering: Don’t over water, but the winds are very drying. Deciduous trees need a bit more water than Juniper and pines. Generally, one watering a day in the morning is adequate unless the winds are up. By mid-afternoon ( 1-3 PM) they should be checked. Water the entire area; ground under the trees, walks, cover overhead, and surrounding garden plants to build up humidity in the air that the winds are drying out. DO NOT WATER a tree if it is in the full sun. Add MirAcid or a small amount of vinegar to your water barrel to neutralize alkaline tap water.

Fertilizing: Use all purpose fertilizer with nitrogen in mild solutions (2 to 1/3 amount called for in package instructions) or mild solutions of soil sulfur, iron tone, or MirAcid. Feed small amounts once or twice a month, not large doses every six months or so. Heavy concentrations of fertilizer can be toxic. See chapter on fertilizers on Naka’s Bonsai Techniques I.

Spraying: Spray for aphids. Mild detergents or insecticide soaps can be used. Protect soil with foil and wash off after treatment.

Trimming & Pruning: Toward the end of April, Flowering and fruiting trees will probably be in bloom. After 80% of buds have blossomed, remove all flowers and remaining buds. Berries may be left on. On fruiting trees, leave a few blossoms or there will be no fruit. See article on nipping and pruning in BCI magazine Jan/Feb 1988.

Repotting: If buds have appeared on deciduous trees, repot now before the leaves open and before the plant flowers. Evergreens can wait as long as the end of May. If repotted last year, they may not need it this year. This depends entirely on the growth pattern of the species.  If tree is in bloom, do not disturb it. Deciduous trees are repotted first. In late April, pot trees that have wintered in the ground, but the same “budding” rules apply.

Grafting: In mid-April, use scions from the refrigerator. Late April–time to start cuttings and seeds under glass jars.