Soils

PROGRAM FOR THE INDIANAPOLIS BONSAI CLUB

Soil and Soil Amendments A two part program presented by Paul Weishaar Revised 2/25/2110

PART 1 SOILS

If there is any one subject in Bonsai that can be termed "controversial", it is soil. It seems every Bonsai enthusiast has a favorite soil mix and will defend that mix to a point that defies comprehension.

Closely following soil mix in the controversial category are soil amendments. Amendments include fertilizers, supplements such as hormones and vitamins, and of course, water. These are discussed in Part 2 of this program.

This program will attempt to cover these subjects in an informative way, which will allow you to create your own mix based upon fact and data, not myths.

This program is specifically tailored to those of us practicing the Art of Bonsai in the central Indiana region and as such, reviews products commonly available either in local garden centers or bonsai retail outlets.

The fact there are so many different ways to create a successful growing medium means trees will tolerate an extreme range of soils and conditions. I think it was Warren Hill who stated during one of his workshops "Some trees live because of the soil while others live in spite of it".

I will caution that there is a lot of misinformation out there, especially on the internet, being provided by self proclaimed experts whom are great at providing extensive verbiage, but not so great at being able to document or back-up what they say.

WHY BONSAI SOIL

The soil you choose to grow your Bonsai in is in effect its sole “life- support” system , therefore you cannot underestimate its importance.

Soil is often the least understood and discussed aspect of growing Bonsai. The other primary areas, watering, feeding, environmental conditions, pest and insect control are important and generally get more attention than soil does. Without appropriate watering and feeding a tree will not be healthy, but good water and feeding habits will be much less effective with a poor soil mix. On the other hand, a good soil can make up for poor watering practice and helps make feeding more effective.

Before getting into specifics of soil ingredients, there are some key items to consider:

The soil has to physically as well as nutritionally be able to support the tree

The soil must remain comfortably damp but not soggy

The soil needs to contain oxygen in the form of vapor/air

The soil must have an acceptable appearance

And finally, the soil must be lightweight to facilitate transporting Bonsai from place to place

SOIL REQUIREMENTS

Due to the special needs of a Bonsai and the limited amount of space in a Bonsai pot, Bonsai soil must provide several basic needs:

Provide drainage:

Sufficient drainage must be provided so that the roots are not constantly in contact with liquid water, which leads to root rot. Roots need air. Most beginning Bonsai artists usually use a mix that is too dense; thinking that what grows the tree best in the earth ought to work just as well in a container. This is not the case. Bonsai is container gardening, which is different from field gardening. Soils for containers should drain 2 to 3 times faster than field soil. The earth acts like a suction pump and literally pulls water from field soils. This same field soil in a container is usually instant death for plants. This is because of the impermeable walls and bottom, which do not allow the soil to drain properly. Bonsai soil mixes should drain so fast that you could stand there and watch water flow thru. As the water flows thru, it must have space for air to replace it.

Provide moisture retention:

The soil should, however, hold some moisture to be gradually released into the air spaces between waterings. A 25% retention by volume is considered optimal. The roots absorb moisture from the vapor created in the air spaces. There must be air. Roots need air. That is why you hear and read so much about using sharp materials in lieu of smooth materials in a soil mix. All parts of a soil mix should be irregular chunks of something, so there can be air between the chunks. Anything that goes into the mix that fills the air spaces is a negative factor …. . A point to remember -- fertilizers and other chemical amendments can be utilized by plants only when they are in a liquid/vapor state. Moisture retention, therefore, includes not only water but also all the amendments, which can be gradually released for use.

SOIL COMPONENTS

Nearly all soil mixes contain two basic ingredients, inorganic and organic matter. Inorganics have never been alive and include materials i.e .sand, gravel, turface, akadama, etc. Inorganics, by themselves, can provide the basic bonsai soil requirements but their use alone creates a high maintenance condition which must be constantly monitored. Synthetic Inorganics is the soil ingredient preferred by most of the Japanese Bonsai Masters.( Synthetics will be discussed later ). It must be remembered, however, that these are people who have devoted their life to bonsai, 24 hours a day, 365 days a year. Most also have interns or others whom help maintain the Bonsai. I do not know about you, but I don’t have luxury of 24 hours a day, 365 days a year to tend to my bonsai nor do I want to hire someone to do this for me. Therefore I must look for ways to minimize the maintenance, which requires creating a mix that works with my environment.

The key to minimizing the maintenance and at the same time creating a great soil mix for use by us non-professional Bonsai enthusiasts is the addition of organic matter. Organic matter is the decaying remains of plants and animals (and animal byproducts) most familiar to us in the forms of peat moss, wood byproducts, animal manure and compost. When added to the soil mix, organic matter lodges between particles and particle aggregates, absorbing some of the moisture as the liquid passes through. Unsterilized organics also provide an instant habitat for all the bacteria and other micro-organisms which help convert and release the beneficial chemical elements. In addition, as the organic materials decompose, which they will, they provide nutrients for the Bonsai.

The components must be neutral relative to ph unless being used for bonsai requiring either acidic or alkaline conditions. The materials discussed here are basically neutral unless noted otherwise.

ph is discussed in detail in Part 2 of this presentation.

What materials are available to fulfill these needs? Keep in mind we are discussing products that are available in the central Indiana area.

INORGANIC MATERIALS THAT PROVIDE SUFFICIENT DRAINAGE:

These are materials that do not absorb moisture but allow the liquid to pass through

SAND

Many Bonsai books recommend "course sand" as a soil component. This does not mean sand such as all-purpose builder's sand or sand box sand. Such sand is too fine for use as a Bonsai soil component and will quickly compact. Course sand is usually a sharp edged gravel or crushed stone that has been sieved to contain particles in the range of 1/16 inch to 1/4 inch. The local sand found in Central Indiana rivers is unacceptable.

LOCAL RIVER GRAVEL

Most gravels found in Central Indiana are of a smooth rounded configuration and are therefore not recommended for use in a Bonsai soil mix.

PREPACKAGED GRAVEL

Here in Indianapolis we have available at the Stone Center, prepackaged sharp edged gravel in 50-pound bags, which come from the Meramec Quarry in St. Louis, Missouri. The cost is about $5.00 per bag. This gravel is ideal for Bonsai soil and is available in 4 gravel sizes. The most popular for Bonsai is designated "WB 40" and consists of gravel approximately 1/8 inch in size and more importantly, does not need to be sieved. A larger size aggregate is available and labeled 1/8 x 1/4. These products are labeled "Aquarium Gravel" which immediately raised a red flag (per many Bonsai books). I called Meramec Quarries and they assured me they did not coat, or treat, the gravel. They have found that the majority of sales for this size gravel are for aquariums, so they started labeling it as such.

AQUARIUM GRAVEL

Nearly all Bonsai books say never use Aquarium Gravel. The interesting thing is they never say why not. Logic says if fish can survive in an aquarium with Aquarium Gravel it must not be toxic. The gravel is not being provided in a Bonsai soil mix for moisture retention so coating it is not an issue. In a recent visit to the local “Pet Smart” store, every prepackaged Aquarium Gravel had either a clear sealer "to eliminate dust" or a coating which colored the gravel. The only reason I can find not to use aquarium gravel in your soil mix is the fact all of varieties I saw were rounded and not suitable for drainage material.

DECOMPOSED GRANITE

Decomposed granite is a very popular sharp edged material that is available at feed stores where it is sold as "chicken grit". "Chicken grit" is already sorted and sized at 1/8-inch particles. If you want larger particles, request "turkey grit". The negatives to decomposed granites are the weight [heavy] and many object to the white color. Many sources say the granite breaks down in 5 or so years. In my opinion you should not let your Bonsai go that long without repotting, so this is a moot point.

OCEAN SAND

Do not use, as the salt is toxic to nearly all trees. No matter how much you rinse you cannot wash out all the salts.

2. INORGANIC MATERIALS THAT PROVIDE SUFFICIENT MOISTURE RETENTION

The inorganic materials usually used in Bonsai Soils are called Synthetics as they are all modified materials. The Synthetic materials are mined all over the world and consist of clay, slate, shale and mica. In most scenarios, after the materials are mined they are quickly heated in rotary kilns. The intense heat ( 1500 degrees F to 2700 degrees F) causes the material to expand due to the presence of water. The material expands quickly, similar to popping popcorn, as the water vaporizes and creates countless tiny bubbles and cavities that account for the lightweight and moisture retentive properties. The material is then ground or pulverized and sorted by particular sizes.

In terms of moisture retainage, the higher the temperature fired the less moisture retained. The high fired materials will last for a long time and are lighter but they do not retain much moisture. The low fired materials will retain much more moisture and many still retain their clay composition, therefore they will break down and decompose over time.

PERLITE

Perlite is a volcanic rock, chemically composed of aluminum silicates, which expands 4 to 20 times its original volume when fired. While the crude rock may range from transparent gray to glossy black, the expanded Perlite is white. As a rule, Perlite tends to last longer, has a more neutral pH and functions better in moisture retention than most of the synthetics, but is not used extensively in Bonsai soils as most enthusiasts do not like the white color. It also has a tendency to float to the surface of the pot when the Bonsai is watered. Perlite is available at most garden centers.

VERMICULITE

Vermiculite is the geological name given to a group of hydrated laminar materials [clays], which are aluminum-iron-magnesium silicates. The pH is essentially neutral [7.0-9.5], but due to the presence of other carbonate compounds, the reaction is normally alkaline. Vermiculite possesses cation exchange properties; which means it can hold and make available ammonium, potassium, calcium and magnesium. The color of Vermiculite will vary from mine to mine but it always seems to have an un-natural, almost manufactured look. Vermiculite, being a low fired clay product, does not last as long as other synthetics. Vermiculite is available at most garden centers.

HAYDITE

Haydite is produced here in central Indiana as well as in other parts of the world from high-grade shale and is an extremely hard product, which is used quite often in face brick manufacture. Haydite is chemically inert and has an absorption rate of 10% to 25% by weight. The color ranges from brown to dark grey. The Hydraulic Press Brick Company in Brooklyn, Indiana produces Haydite in bulk quantities of 6 gradients. "A" grade is about 1/8 inch, while "AX" is 1/8 inch to 1/4 inch. Either is excellent for use in Bonsai soil. The products need to be sieved to eliminate the dust size particles, and unfortunately the loss is about 50%. Recently the Haydite Corp has began packaging a “Bonsai” mix which appears to be the AX grade. It has been sieved and it is available at the Brooklyn, Indiana plant.

SOLITE

Solite is mentioned in many Bonsai articles as an acceptable product for Bonsai soils. Solite Corp. does not promote or recommend the product as a growing medium amendment. Their product data does not state specifically what the base material is. They say "shale, slate or clay"! Without more specific data, I do not think it appropriate to comment pro or con on its use in Bonsai soils.

TERRAGREEN

Terragreen is the soil additive brand name of the Oil Dri Corporation. It is a medium fired clay which is pinkish tan in color, sold in 50 pound bags and is mined in Georgia. It is sized mostly 1/8 To 1/4

Inch , requires minimal sieving and is widely used for Bonsai. It seems to be hard to find here in Central Indiana

KITTI - DRI

Kitty – Dri is a cat litter also manufactured by the Oil Dri Corporation. It is mined in Ripley, Mississippi and is greyer than Terragreen. It is not fired to as high a temperature as Terragreen and therefore absorbs a very high amount of liquid and is not stable over a period of time. It is, however, satisfactory for moisture loving Bonsai which are repotted every year.

CAT LITTER

Cat litters are manufactured primarily from bentonite clay products. Bentonite clay is used in the construction industry as a waterproofing product you use on below-grade walls. When the clay gets wet, it creates a hard monolithic product, which will not allow water to penetrate. Many litter manufacturers promote this characteristic of bentonite clay. To quote one package, "___________ has strong clumping, action when exposed to solid or liquid waste. It will not break apart when the cat scratches in the box or during removal". Not exactly a product you want in soil when one of the criteria is free drainage. Most cat litter also has chemicals added for odor control. Once again, there is no research as to the effect of the added chemicals on plants and cat litter is a single purpose product which does not return to its original composition when, or if, it drys out. The positive to using cat litter in Bonsai soil, is it's extremely lightweight.

OIL DRI

The Oil Dri Corporation markets another product named, appropriately enough, Oil Dri. Guess what………it is the same identical product as Kitti Dri. Just a different name for a different market.

OTHER OIL ABSORBANTS

Most absorbents are made from either clay or cotton by-products. Their manufactured purpose is to quickly absorb greases and oils from floors. The pro on absorbents is they are extremely lightweight and able to retain vast amounts of moisture. The negative is they are designed to be single use products, that is, once they soak up liquid, they are designed to be discarded and do not return to their original composition. Also, when used for their manufactured purpose they become toxic waste when they absorb oil. To solve this, the manufacturers are now adding chemicals, which biodegrade the oil in about 6 months, which allows the absorbent to be discarded with normal trash. There is no data on what effect these chemicals have when used in a soil mix or on what "witches' brew" might be created when mixed with fertilizers or insecticides. If you use absorbents make sure it contains only clay.

TURFACE

International Minerals Corporation markets synthetic products for athletic fields under the brand names Turface MVP Soil Conditioner, Turface Coarse and Turface Extra Coarse. Turface MVP Soil Conditioner is the most popular synthetic used in Bonsai soil due to its particle size. It is available in a multitude of colors. Turface is very similar to Terragreen and, in fact, is mined in the same town as Terragreen, Ripley Mississippi. Turface is very moisture retentive.

AKADAMA

This is the synthetic that is widely used in Japan. .Akadama gets its name from the Province in Japan where it is mined. It is available in numerous gradients of both low fire and high fire and is slightly acidic. Interestingly, the products sold as medium size in Europe are labeled large in the USA. Be aware the low fire retains considerably more moisture and I have had it break down within 6 months. Akadama medium fired seems to have just the right balance between drainage and moisture retention and is often used with no other materials added. The drawback is the high cost due to importing from Japan.

KANUMA

Kanuma is another synthetic imported from Japan. It is different from Akadama and most other synthetics in that it maintains an strong acidic quality ( low ph ) and is therefore excellent for many broadleaf species i.e. Azaleas. It is available in two gradient sizes and as Akadama, is quite expensive.

3. ORGANIC MATERIALS

The use of organic materials provide additional moisture retention capability and also provides the necessary micro-environment for the health of the Bonsai. Sterilized organics can be “unsterilized” by adding small amounts of unsterilized material which introduces the microorganisms into the mix. In addition organics decompose providing additional nutrients. You must remember that the smaller the particle size, the quicker it will decompose. This could require repotting every year.

PEAT MOSS

Spaghnum peat moss is a common product available at garden centers as a supplement to garden soils to "keep soil loose" and provide moisture retention. Peat moss can be used in Bonsai soil and is great for water retention. But be aware, it is a very fine material which tends to compact and if it drys out is very hard to wet again, in fact, has a tendency to shed water. Peat moss in its pure form is acidic and works well with acid loving plants. Most manufacturers add limestone particles to their peat to neutralize the ph. So if you are looking for an acidic component, check the ingredients.

COMPOST

Any time you use compost [unless it has been pasteurized] or native soil you run the risk of introducing pathogens, insects and other pests as well as the beneficial organisms. Compost, if not aged, can also cause root damage due to the heat created by its high speed decomposing. On the positive side aged compost does provide vast quantities of organic nutrients and trace elements.

PINE BARK

Fine chip composted pine bark mulch when sieved makes a very suitable organic soil component that is on the acidic side of the scale. Composted is the key word as there is data available which indicates fresh bark can hinder absorption of nutrients by the roots. Particles 1/8 inch to 1/4 inch should be used for large trees and those that prefer dryer soil. 1/8 inch [fine] may be used for small trees and those that prefer moist soil. Pine bark has the ability to absorb water and later release it in vapor form. Exactly what you want! Bark also will promote beneficial fungi. Composted pine bark of the size needed is not usually available at garden centers. Here in central Indiana a fine composted pine bark it is available at Greendell Farm, Inc., just west of Mooresville, Indiana. Take your buckets or trash bags and plan to spend $3.00 to $4.00. Sometimes they have some bagged for bonsai.

OAK LEAF MOLD

Oak leaf mold is composted material that is a minimum one year old and preferably two years old. This aging process gives the beneficial soil fungi time to develop. The mold also stores moisture and is high in nutrients while providing trace elements. Excellent product for inclusion in deciduous Bonsai soil mix but will decompose over a period of a year. Oak Leaf Mold is used extensively in the southeast USA but is extremely hard to find in the Midwest. It is also quite expensive.

4. SOIL-LESS PACKAGE MIXES

Commercial growers use these package mixes with great success as they are able to control the environment in their greenhouses. We lose that control when placing Bonsai outside so these mixes are usually unacceptable as they hold too much moisture.

Metro Mix, Peters Professional Potting Soil, Wonder Mix, Pro Mix ,these are examples of the soil-less growing mediums and are available at garden centers. They contain products like Vermiculite, Peat Moss, Perlite, composted pine bark, processed bark ash and washed sand. Check the ingredients to determine if the mix has what you want. As noted before, many object to the white colors of Vermiculite and Perlite which most package mixes have. Another drawback to soil-less mixes is the tendency to use very fine particles of materials. This requires the use of a sieve and you can sieve out as much as 60% of some of the mixes. This stuff is expensive to begin with and then you may have to throw 1/2 of it away!

The only exception seems to be Wonder Mix. It is quite popular in the southern states. Wonder Mix is a sterilized organic soil-less mix which has no Perlite or Vermiculite and is often mixed with synthetics to create an organic/inorganic mix.

5. PREMIXED BONSAI SOILS

Many Bonsai Nurseries have pre mixed Bonsai soils for sale. Many have more than one mix available and are excellent choices for those who have a small Bonsai collection. The negative is the high price you must pay for small quantities.

MATERIAL SIZE

Is soil material size important? You bet it is. Does a layer of coarse granular material in the bottom of the pot improve drainage? It does not. Wait just a minute…..That is contrary to what every Bonsai book says! Recent studies have disproved this theory. In order to understand the answer to this question we must first understand some basic principles of soils and the factors affecting water movement through it.

Soil structure or the arrangement of soil particles is a very important aspect of soil management. Sharp edged granular soil, free of dust or fines is the most desirable soil structure in which to grow Bonsai.

When water is applied to a soil it would immediately fall through do to the pull of gravity if it were not for the forces of adhesion and cohesion.

ADHESION is the binding force of molecules of unlike substances when brought

into contact ( soil and water particles )

COHESION is the binding force of the same substance ( water to water )

With these principles in mind we can better understand some examples of water moving through varied soils and mixes in containers. Studies made at the University of California and the University of Washington confirm the following:

Fine soils will hold more water than course soils, and therefore, water moves more slowly through them. Soil particle size, structure, material, adhesion, and cohesion, which we have discussed, all have an effect on the rate of water movement through the soil. If an interface, or layer of substances of different particle sizes, is placed at any point below the surface of the soil, it will impede the movement of water through it. The soil above it will become completely saturated before water will move through the interface. Therefore, larger particles placed in the bottom of a pot will actually hinder, rather than improve, drainage.

Although this is a proven principle, it is hard to understand. A good illustration of this principle is a dripping faucet. If you watch the drop of water on the end of the faucet, you will see it that it grows larger and larger until it finally falls off. Adhesion is the water holding on to the faucet, cohesion is the water drop getting larger. The drop of water getting larger is the equivalent to water moving through soil of small particle size until it meets a layer of larger particles and stops, as the drop grows larger the soil above becomes saturated. If you were to test the soil moisture at this point by sticking your finger in the surface you would think it very wet, while in fact it may be dry at the root level. Once the adhesion is broken the water moves quickly through the larger particles and actually sucks the water from the above layer. The most efficient method for soil drainage is to provide a uniform mix.

ENVIRONMENTAL CONDITIONS

You must take into consideration the environmental conditions where you will be placing your bonsai when determining your soil materials. A Bonsai placed in full sun all day needs a soil mix that will retain moisture. If not you will be watering it numerous times during a hot sunny day. On the opposite scenario a Bonsai kept in full shade with a covering of moss needs a much more porous soil mix to keep the roots from rotting. Only you can determine the environmental conditions

MIXING ORGANICS AND INORGANICS

Remember the two soil components, organics and inorganics. Well, it is time to mix each.

INORGANIC MIX is usually comprised of 50% drainage material and 50% moisture retention material. You can go thru the list and use whatever products appeal to you. Remember to consider your environment when choosing the percentages.

ORGANIC MIX can be any percentage of the products noted depending upon their availability.

Now we have two buckets, one with inorganics and one with organics. The next step is to determine the proper proportions for the type tree you are repotting. The best list I have found is in Herb Gustafson's book, "THE BONSAI WORKSHOP". The list follows but you should read his book to understand why:

GROUP 1 -- 3/4 organic

1/4 inorganic

Azalea, Rhododendron, Bald Cypress, Tropicals, Redwood

GROUP 2 -- 2/3 organic

1/3 inorganic

Alder, Birch, Hornbeam, Beech, Elm, Zelkova, Maple, Dogwood.

GROUP 3 -- 1/2 organic

1/2 inorganic

Pyracantha, Boxwood, Cotoneaster, Quince, Holly, Fig, Cororia, Fruit Trees and

Wisteria.

GROUP 4 -- 1/3 organic

2/3 inorganic

Larch, Ginko, Fir, Spruce, Hemlock, Cypress, Cryptomeria.

GROUP 5 -- 1/4 organic

3/4 inorganic

Oak, Pine, Juniper, Alpine and Desert Plants, Jade, Eucalyptus

Most Bonsai enthusiasts simplify the list into 3 groups in lieu of the five. Many only use two mixes. This simplifies the list and Bonsai should not only survive but thrive quite well.

GROUP 1 Soil mix as proportioned

GROUP 2, 3 and 4 Soil mixes are combined into one group and proportioned as shown in GROUP 3.

GROUP 5 Soil mix as proportioned

MY PERSONAL SOIL CHOICE

The inevitable question always comes up “ What do you use”. For most of my bonsai I mix the organics and inorganics as per the simplified 4 Group mix. Why group 4 you ask? I do not have full sun all day and thus my bonsai require a higher drainage mix to prevent root rot. While I am always on the lookout for new products and information, I have used the following mixes for a number of years with great success. I must note this success cannot be attributed to the soil mix alone but my understanding of my environment and also the use of appropriate additives as discussed in Part 2 Amendments.

ORGANIC MIX

For young trees which will be repotted each year the organic component consists of about 90% composted pine bark and 10% oak leaf mold. The oak leaf mold provides more nutrients but as noted, will decompose within a year.

For trees which are not repotted each year the organic mix is 100% composted pine bark.

INORGANIC MIX

I use 50% Akadama and 50% Haydite. Both are moisture retentive but to different degrees. The 50-50 mix works well in my environment. I also have a personal preference for the visual image presented with the multi colored soil mix, the Akadama being a brown color and the Haydite grey.

For trees displayed in a partially or fully shaded area or those which have a high percentage of ground cover, ie moss, I use about 80% Haydite and 20% Akadama. The Haydite provides for quicker drainage which is necessary under these conditions.

AMENDMENTS

I always add mycorrhizza to my soil mix. Mycorrhizza is discussed further in PART 2 - SOIL AMENDMENTS

PART 2 SOIL AMENDMENTS

For the purpose of this discussion amendments are defined as any favorable item you can or should add, either in liquid or solid form, externally to your Bonsai or into your soil mix. These items include such basics as water and fertilizers as well as vitamins, hormones, micro-organisms, ph adjusters and other special use additives. Whatever the amendment is, the only way it can be utilized by the plant is to be in a soluable form the plant recognizes. This is the primary difference between manufactured and organic products

WATER

Gardeners often describe water as the necessary evil, you have to have it but too much or too little will create devastating results. If you have created a good Bonsai soil mix as we discussed in Part 1 of this program, you are off to a good start because there is little point in supplying water to trees that are unable to make productive use of it due to poor soil or poor soil management.

The most frequently asked questions are “How much should I water” or “ How often should I water “. The answer is only when the tree is thirsty. This is actually the hard part of learning to water. Every where you read or talk about watering you get instructions like “ water daily” or “ water weekly”. You must adapt to the instruction “ water only when needed “. You have to get to know your Bonsai and sense their needs. There are just too many variables, soil, rain, temperature, wind, sun, humidity, clouds, drainage, pot size and material, etc, to say water ten minutes every day.

As we mentioned earlier, by controlling the soil mix you can control the amount of water necessary. For instance, if you have a tree which needs a lot of water, prepare a mixture that retains the water. Conversely, if it is a tree which needs less water, use a more porous soil which drains rapidly. By doing this you you can water all your trees at the same time and the soil mixes will adjust the timing of when you water them again.

Potbound Bonsai dry out faster and will require watering more often than those with a normal root structure with a soil buffer. Newly potted bonsai, on the other hand, demand very little water until transpiration is restored and new growth is evident. Over-watering newly potted Bonsai which have been root pruned, except at the initial watering to settle the soil, is a frequent cause of failure.

If you have the soil mix based on the needs of the tree you should not have to worry about over-watering during the growing season. In the Spring and Fall you must adjust your watering schedule as the trees need much less moisture therefore the soils retain moisture longer. Remember, most stress to which Bonsai are subject, including spider mite and disease, is a by product of the over-watering syndrome.

“How and when do I water “ is another frequently asked question. Psychologically, hand watering my Bonsai is one of the more pleasurable times of the day. Never think of watering as a chore. Think of it as a pleasure. This is when you can relax and look and enjoy each and every one of your trees. What does this have to do with the question ? Two answers…. If you have an automatic sprinkler watering system which waters everything including soil, pot, foliage, trunk and anything else in the vicinity , it is recommended you water in the early morning before the sun rises. This allows the Bonsai time to absorb the moisture both thru the soil and foliage prior to the heat of the day while at the same time not creating an extended period where the moisture stands and creates an environment in which harmful bacteria and fungi can grow. Standing moisture also attracts insects. If, on the other hand, you walk through the Bonsai and hand water, it is recommended you do this in the evening and only water the container. This allows the Bonsai all night to utilize the moisture in the soil while not providing the environment for the insects and fungi.

One other comment on when to water…..Do not water for a day or two prior to doing any major bending of a branch or trunk. Withholding water will make the tree more flexible and minimize the chance for breakage.

TYPES OF WATER

SOFTENED WATER

Water softeners of the Zeolite type ( the most predominate type ) produce water that can injure trees. The Zeolite softener replaces the calcium in water with sodium. Calcium is the element that makes the water “hard”. The sodium does not settle out or evaporate; in fact, it accumulates in the soil and container. Long term use can cause soils to become less permeable and can cause sodium-sensitive plants ( citrus, orchids, etc ) to burn. If you cannot bypass the water softener you have to counteract the softening process.

A few years ago the Cooperative Extension of the University of California issued advice on treating soft water for use on plants. “ Softened water can be treated to eliminate these hazards. The treatment involves simply adding calcium that was present before softening removed it. This can nullify the effect of sodium added in the softening process. Gypsum ( primarily calcium sulfate ) , available at most nurseries, is a cheap and safe material to use for this purpose. Its safety feature is its relatively low solubility yet enough gypsum can be dissolved to treat softened waters effectively. One-half teaspoon per gallon of water should be sufficient in most cases to supply the necessary calcium to change the water to an unsoftened state.” Gypsum also dissolves existing salts.

In following up on this advice as it pertains to watering Bonsai of a larger quantity where you use a hose or irrigation system , I could not find any published data. In talking with some Bonsai nurserymen around the country most suggested sprinkling a light covering of gypsum over the soil about once a month. As the gypsum is slow dissolving this should suffice.

DISTILLED WATER

Using distilled water (water which has had all salts and other solids removed ) may seem extreme but it is beneficial. If you have a limited amount of Bonsai or have small Bonsai (mame), using distilled water should be considered as it will prevent the salt build-up in soil and on pots. Instead of using commercial distilled water you can collect rain water in large barrels. Rainwater , thru the process of evaporation over 48 hours +/- , is naturally distilled.

HARD WATER

In areas where the water is very alkaline (commonly known as hard water ), such as here in central Indiana, it is difficult to grow many species of trees, especially acid loving trees, without modifying the ph. Ph is measured on a scale from 1(acid) to 14 (alkaline) with 7 considered neutral. Indianapolis water has a ph of 7.4 , Greenfield 7.6 and Bloomington 7.9. What is ph ? Having ask that, that this is probably as good a place as any to discuss ph.

UNDERSTANDING pH

pH is a complicated chemical measurement that determines the concentration of hydrogen ions which regulate the acidity or alkalinity of the medium. The scale ranges from 1 to 14. Low numbers indicate an acid environment, high numbers indicate alkaline. Halfway, or 7, is neutral. Ph can only be measured in a soluble form.

While ph is critical when it is considered in the light of agricultural yields, the only importance of ph in bonsai soils is its influence on the ability of the plant to absorb nutrients. Most plant-essential nutrients in soil reach maximum availability in the ph range of 6 to 7 and they decrease both above and below this range. In addition, the activity of various micro-organisms, which are essential to plant health, can be strongly dependent on ph.

It is noteworthy that most woody plants we use for bonsai include this range ( 6 to 7 ) in their total range of ph preference. What this means is that various species of plants can only absorb nutrients when the ph is in their range. There are a few exceptions to this range of 6 to 7, eg on the low side the rhododendron family ( ph 4.5 to 5 ) and on the high side most desert plants ( ph 7 to 8 ).

Since we are are actually determining what our trees are growing in it makes it simpler to analyze the ph. The majority of the soil components presented in Soils Part 1 and used today are synthetics and as such are neutral. Only a few are slightly acidic ( peat moss, akadama and kanuma ). This translates to the fact the ph of the water you use may be far more important than the soil in determining the ph of the medium which in turn dictates the ability of the tree to absorb the nutrients. Remember we noted earlier the Indy water has a ph of 7.4. Use that as a starting point.

So how do you change the ph? If you want to bring the ph to a neutral range add some gypsum. To raise the ph, which creates an alkaline condition, add lime in the form of granular dolomite limestone ( available in small quantities at garden centers ). To move the ph to a lower range, or acidic, you must add iron sulfate or aluminum sulfate. Rather than trying to find these chemicals individually the fertilizer manufacturers have made it easy as they have added both chemicals to fertilizers noted for acid loving plants. You can fertilize and control the ph in one step.

CHEMICALS IN WATER

Chemicals which are commonly added to our domestic water supplies do no harm to plants. There is no evidence or study that Fluorine has any effect, good or bad. Chlorine, the other substance usually added to city water passes off so quickly when in contact with air that most of the chemical is dissipated while the water is running into your watering can, the rest passing off as gas when the water reaches the soil.

GYPSUM

Gypsum is one of those rare materials that perform in all three categories of soil treatment: an amendment, conditioner, and fertilizer. Gypsum amends soil alkalinity and acidity as it lowers high pH conditions and raises low pH conditions. Gypsum also counteracts with and leaches out harmful salts. Salts is the common generic name given to non-soluble material particles that are introduced thru various solutions and remain in the soil. A build-up of salts halts the absorption of nutrients by the roots. Central Indiana water is high is non- soluble salts, therefore gypsum is recommended as an additive to Bonsai soil. A handful in a 5-gallon bucket of soil is adequate or it can be lightly sprinkled on existing soil on a monthly basis. Gypsum conditions and improves soil structure allowing air and water penetration and root development. Gypsum is 100% Calcium Sulfate.

SUPERTHRIVE

Superthrive is one of those products you immediately are wary of. If you have ever read their brochure or container, you find they guarantee the product will do everything in the world……..60 years unchallenged, #1 grower, #1 activator, #1 transplanter, etc, etc………. The drawback is they do not include a list of ingredients. The closest they come is touting 50 vitamins and hormones. But you know what, I have found no one who says anything negative about it and it seems everyone uses it [including me]. It is strongly recommended you follow the mixing instructions of 1 drop per gallon since we don't know the ingredients. This is mentioned, as I have seen articles in Bonsai books that recommend 10 to 20 drops per gallon. Most users recommend adding Superthrive whenever you water.

MYCORRHIZA

Most trees have a mutually advantageous association ( symbiosis ) with a fungus. This living together of a fungus and a tree root is called a symbiotic mycorrhiza. The word, micorrhiza, itself means fungus-root.

Basically, the fungus grows on and within the roots to provide a mutually beneficial relationship. The micorrhizal fungi hair roots ( hyphae ) greatly increases the nutrient absorbing surface and often extend the absorbing perimeters beyond the root surface. In return, the fungi obtain carbohydrates from the roots for metabolic purposes.

Old anchor roots which have lost their root hairs do not readily absorb food. The mycorrhiza provides hair root substitutes in the form of the hyphae.

For many years it was thought that mycorrhiza benefited only pine trees but recent research has shown that all but three plant families benefit from the mycorrhizal association. The three families are Chenopods, Mustards and Rushes/sledges, none of which are used for bonsai.

Mycorrhizal fungi ( 12 species in package ) is available in composted pine bark packaged by the Hollow Creek Nursery. It can be ordered at stonelantern.com. This is the only source I have been able to find. The mixture also contains five trace elements.

Beware of obtaining mycorrhiza thru the US Mail. After the recent Anthrax situation mail is being Irradiated to kill anthrax spores. This also kills mycorrhiza.

FERTILIZERS

Why do we fertilize? The answer lies in the soils we use and the fact Bonsai is a form of container gardening. In our quest for the perfect growing medium we have arrived at a point where we are using a sterile or nearly sterile mix. In this totally artificial environment, we now have to provide most if not all the necessary nutrients to maintain the health and growth of the trees.

Unlike we gourmet diners, plants cannot distinguish between their sources of nutrition. Whether the elements come from factory, animal, garden, or ocean, a plant uses nutrients only when in their absorbable ( ionic ) form. Therefore the difference in all fertilizers is how long it takes a nutrient to reach the stage where it becomes useful to the plant, what it carries with it, cost and convenience.

There are 16 elements necessary for proper plant development. If even one of the elements is missing the plant may not grow to its optimum potential

MAJOR ELEMENTS

Federal law requires a chemical fertilizer label to list the three major elements, or macronutrients, Nitrogen (N), Phosphorus (K) and Potassium (P) in a precise order ( 0-0-0 ). To list it is to guarantee it. Organic fertilizer packagers are not required to do this, however, most are now doing it due to public demand. Similarly there is no requirement of anyone to list any of the other elements , minor or trace, but many are including them.

NITROGEN [N] , the first element, is necessary for above ground vegetative growth, giving leaves and stems a healthy green color. If it is lacking, the new leaves take what little there is and the older leaves turn yellow and fall off. While some nitrogen comes from the atmosphere, most of it comes from fertilizers that must be absorbed thru the roots.

PHOSPHORUS [P], the second element, also contributes to the green color of the leaves but it is more important for root development and the formation of seeds, flowers and fruit. Increased disease resistance is another benefit.

POTASSIUM [K], the third element, is necessary for photosynthesis. Without photosynthesis, plants starve. Potassium also improves the rigidity of trunks and helps plants overcome adverse soil conditions. Potassium is especially helpful when applied in the fall to increase winter hardiness.

MINOR ELEMENTS

The next three elements, Carbon, Hydrogen and Oxygen come from the atmosphere and from water. You will not find these on fertilizer labels.

TRACE ELEMENTS

The remaining elements are in quantities too small to be measured accurately. Many packagers are beginning to list the ones they include. I do not like to list proprietary products but at the present time I have found only one fertilizer that contains all major and trace elements: Liquid Grow Plant Food (7-9-5) by Dyna Gro Products.

WHAT STRENGTH

In my research for this program, I found numerous directives on the Internet and also in many Bonsai books that state liquid; inorganic fertilizers are to be applied at 1/2 the recommended strength. No where could I find any documentation or reason why. Is this one of those infamous myths? After many fruitless calls and conversations, I finally talked to representatives of major manufacturer, whom package both fertilizers and soil mixes. I posed my question and they said they have heard and read this numerous times and know of no data to substantiate the myth. Their proportions are based upon what the plants need.

They stated all fertilizer manufacturers do extensive testing of their products to provide optimum results under "normal" conditions over a specified time. All fertilizer containers provide two basic mix formulas: Outdoors [for planting in the ground] and Indoors [sometimes called container gardening]. Indoor formulas are based on using a "standard" potting soil available at garden centers. They gave me a lot of facts, data, numbers etc. and ultimately suggested it would do no harm to cut the strength in half as long as you realize the plant is only getting half the nutrients it needs. To compensate this shortfall you must fertilize twice as often.

The ingredients N, K, and P are listed on the label as 10-10-10 , 18-6-12, etc. These numbers are basically the percentage , by weight, of the NKP in the package. Is 20-20-20 better than 10-10-10 ? No ! The mixing or application instructions take the percentages into account, in other words you might use ½ as much 20-20-20 in a gallon of water as 10-10-10.

You have all heard the term 'fertilizer burn', or heard someone say too much fertilizer will burn up the roots. Damage can occur with too much inorganic fertilizer, but not in the way most think. Plants absorb moisture and nutrients thru the roots by means of osmosis. When too much of certain elements are applied, it actually reverses the osmosis process and sucks the moisture out of the plant. The soluble complete fertilizers are the ones to be extra careful with (see fertilizer forms listed below). If you realize you have over-fertilized, water, water and water. Wash that fertilizer out.

FERTILIZER FORMS

Is any one kind or form of fertilizer best? Unfortunately there is no true answer all the time, in any situation. Each kind and form of fertilizer has its own advantages and disadvantages. Only you can ultimately decide which fertilizer works best for you in each situation .

There are five primary forms of fertilizer we normally use for bonsai. Each is listed with the advantages and disadvantages as well as any pertinent comments.

SIMPLE OR SINGLE USE FERTILIZERS

Advantages: Inexpensive and very concentrated .

Disadvantages: Because they are concentrated and often soluble, it is easier to damage plants by

applying too much---especially nitrogen fertilizers

Other nutrient needs can be easily overlooked

You must be knowledgeable enough or have a soil test to positively identify the

lacking nutrient

Exanples: Fertilizers such as blood meal ( 10-0-0 ), bone meal ( 0-11-0) and potash

( 0-0-55 ) are widely available examples. Almost always sold in powdered form.

SLOW RELEASE FERTILIZERS

Advantages: These are labor saving fertilizers. More can be applied at one time, reducing the

frequency of feedings.

The feeding is gradual so plants are not shocked .

One application may last anywhere from three to nine months

Disadvantages: Cost is a factor. Time release fertilizers are always more expensive

Some are activated to release nutrients by water, others by warm temperatures,

therefore the rate of nutrient release is not constant and somewhat unpredictable.

This quite often may be too slow during periods of rapid growth.

Slow release fertilizers are very conservative and therefore quite often provide

minimal nutrients. Growers often use this form of fertilizer when repotting as

there is little to no chance of burning new or undeveloped roots.

Examples: Osmocote—available in two formulas: 14-14-14 lasts 3 months and 18-6-12 lasts

8 to 9 months. Activated by soil temperature and microbial activity.

Others examples are Dynamite ( offered in two formulas ), MagAmp , IBDU and

Orthos Pot and Planter food.

PARTIALLY SOLUBLE COMPLETE FERTILIZERS

Advantages: These are the fertilizers most often used for general garden purposes.

Many formulations for specific groups of plants exist: rose food, lawn food,

orchid food, house plant food, etc.

They supply in one application the mineral elements plants need most: nitrogen,

phosphorus and potassium.

Because of their partial insolubility, they will supply some nutrients over a longer

period of time than the soluble complete fertilizers do.

These fertilizers are available in many forms: liquid, granules, powders, spikes, etc

Disadvantages: Due to the partial insolubility some nutrients ( copper, manganese, zinc and iron )

may not be available immediately. These elements are chemically modified so

their release is delayed to prevent root burn.

Have to be applied more often than other forms of fertilizers. Many are designed

for application every two weeks. If you are applying at half strength this means

application every week.

If not used with frequency recommended plants will starve between applications

SOLUBLE COMPLETE FERTILIZERS

Advantages: Because these fertilizers are 100% soluble in water, all the nutrients they contain

are available immediately for use by the plant. The term “chelated” is the clue to . identifying 100% solubility.

Available as dry crystals or concentrated solutions

Nutrient availability is more dependent on moisture than temperature which means

they can be used in early spring or late fall while the soils are cool.

The effects of application closely follow application.

Available in every conceivable combination of elements, including trace elements

Disadvantages: These are the fertilizers that can be misused. You must follow the instructions.

A dose too strong can “burn” leaves and roots or even cause death.

If not used with frequency recommended plants will starve between feedings.

NATURAL ORGANIC FERTILIZERS

Advantages: Improves soil structure with arrival of microbes necessary to convert nutrients into

a form plant can absorb

Slow release of nutrients reduces the danger of over fertilizing and when provided

in cake form provides a constant steady flow of nutrients.

When applied in solid form ( cakes or pellets ) the application can last for weeks

and in many instances months.

If you make your own solid units you can create whatever mix of elements your

trees need

Available in both solid and liquid forms in many mixes of elements

Disadvantages: Microorganisms do not become active and convert nutrients to a form the plant can

use until the soil temperature reaches about 60 degrees.

Liquid applications are not very efficient as many of the elements will leach out

before the microbes have time convert the nutrients into a form the plant can

absorb.

Most premade solid cakes and pellets are imported from Japan and are quite

expensive.

Rape seed pellets, one of the popular imported fertilizers, has been found to leave

high concentrations of insoluble salts in the soil.

Hachi Dama , another popular Japanese imported fertilizer cake, along with most

other cakes and pellets are presently banned from import into the US as they

contain animal by-products. (mad cow disease)

Organic fertilizers are notorious for smelling and attracting insects

Results are not available immediately as it takes time for microbes to convert

nutrients. This is only significant on first application.

Cakes and pellets will kill vegetation upon contact. Do not use with ground covers

or moss

MY PERSONAL SOIL AMENDMENT CHOICES

It appears there is only one fertilizer available that contains all 16 required elements ( Dyna Gro 7-9-5 ), so this is what I primarily use. I do use other brands occasionally. I use 0 nitrogen fertilizer on the pines in the spring until the new needles harden and then revert to Dyna-Gro. This keeps the needles short.

Specialized fertilizers are used for flowering and acid loving bonsai.

Soluble complete and partially soluble fertilizers are used exclusively. I have used other forms at one time or another and for various reasons have simplified what I use.

I also use gypsum and superthrive.

A number of years ago Julian Adams, a noted bonsai enthusiast, convinced me to add an application of a micronutrient supplement early each spring. Since then I have definitely seen positive results both in color on all species and little or no leaf damage on my deciduous trees in the hot summer. The product I use is Earth Juice Microblast, which I found at a local Hydroponics store. In the 2009/No.2 issue of International BONSAI, Julian authored an article on Soil and Nutrients which discusses micronutrients.

SOME SIMPLE RULES ON FERTILIZING

DO ! DO ! DO !

Do fertilize during the active growing season

Do fertilize while the soil is moist to prevent root burn and to promote even distribution of fertilizer

DON’T DON’T DON’T

Don’t fertilize after transplanting. Wait until new growth appears

Don’t fertilize in hot, mid summer

Don’t fertilize in winter

Don’t fertilize a weak or sick plant unless weakness is due to lack of nutrition; then feed very gradually

GENERAL COMMENTS

No fertilizer is better than too much

Conifers generally do not need as much fertilizer as deciduous trees

Older, more mature trees do not need as much fertilizer as young, vigorous trees

Alternate brands of fertilizer throughout the season to provide a broad spectrum of nutrients

Flowering trees should be fertilized before and after the blooming season, but not while in bloom