Bonsai: a reflection of nature, captured in miniature, as seen through the eyes and soul of the practitioner

First off I would like to thank Galen Camp of Virginia Beach for contributing this piece. I think this covers it a lot better than I could have. So with that in mind, read on....



BONSAI SOIL If you walked into a room filled with Bonsai enthusiasts and asked the question "What makes good Bonsai soil?," you'd get a different answer from everyone there. Soil is one of the most diversified areas in Bonsai. The reasons for this fall into several categories... personal choice, aesthetics, geographic location, plant material and even how much time you actually want to spend watering! Good Bonsai soil can provide you with many benefits. First and foremost would be improved drainage which is essential for healthy root growth. Selecting the proper particle size can further help by providing greater surface area on which roots can grow. There are five things to consider when making your Bonsai soil: particle size, texture, composition, aesthetics and developing microoganisms.

PARTICLE SIZE To put it simply... size matters. Large is not always better when it comes to Bonsai soil. Sure a larger particle would provide more surface area for roots to cling to but it would also take up more room in the already small container. If the particle is too small the pieces would be so close together that the surface tension would create a capillary effect and actually draw water away from your roots. The easiest way to ensure a good particle size is to screen your materials. A square frame about 16 inches on a side and three inches high is all you need. Staple 1/8 inch hardware cloth to remove the largest of particles. Another can be made with common window screen to discard the smaller particles.

TEXTURE Another factor to consider is the texture of your particle. A smooth particle will have much less surface area than a rough particle of the same size. Growing roots will also slide along the smooth exterior, flowing around and between smooth particles while rough particles will tend to "irritate" the roots causing them to divide and redivide into thousands of tiny root hairs. The more twiggy and detailed the roots... the more twiggy and detailed the branching will be.

COMPOSTION This is the heart of Bonsai soil. Most of us understand that what makes good soil for one plant might not for another. A good basic formula is one-third sphagnum moss peat, one-third coarse sand, and one-third ordinary garden soil or loam. This recipe should be suitable for most trees but it can be varied depending on species and special requirements. Pines for example prefer sandy soil, especially older pines which may prefer a soil that is almost 50% sand or grit. Flowering trees prefer loamy soil. You can study for years and learn the specific pH requirements of specific trees and develop a formula for each but particle size is much more important than the actual pH. As a general guideline, break your materials down into two groups based on availability in your location... Organic and Inorganic. Organic particles would contain bark, sawdust, leaf mould, or compost from the garden. Inorganic might include crushed lava or pumice, sand, decomposed granite, vermiculite or perlite. These particles have never been alive and are usually high in pH. Now I'll give you some examples of possible soil mixes for different types of plant material.

For Azalea, Bald Cypress, Redwood and more tropical type plants you would use 3/4 Organic and 1/4 Inorganic. For Dogwood, Maple, Alder, Beech, Birch, Hornbeam, Elm and Zelkova use 2/3 Organic and 1/3 Inorganic. Pyracantha, Wisteria, Holly, Boxwood, Fruit trees and Cotoneaster would do well in a half and half mixture. Gingko Biloba, Spruce, Fir, Hemlock, Cypress and Larch would prefer 1/3 Organic and 2/3 Inorganic. Finally, Pine, Oak, Juniper, and alpine or desert plants do well in 1/4 Organic and 3/4 Inorganic. You can base your soil mix on the environment where the tree grows in the wild. Pines benefit from the needles they drop as well as from the loamy forest floor. I have some trees growing in a mixture of crushed rock and calcinated baked clay particles while others are in simple "Miracle Grow" potting soil. Use what works. If the tree isn't doing well... alter your soil mix until you get it right.

AESTHETICS One component important to most Bonsai hobbyists is artistic expression. A beautiful tree specimen displayed in the wrong pot or with a soil that is less than pleasing to the eye can kill the overall presentation of the tree. I personally don't like white particles in the soil so I shy away from perlite. I also don't like the "fish scale" appearance of vermiculite. This is one area that is really up to the personal preference of the artist. The tree could care less about the appearance of the soil as long as the particle size and mix will sustain it. My favorite materials to use are screened "Orchid Mix" for my Organic material and crushed lava rock and "rainbow" rock for my Inorganic.

DEVELOPING MICROORGANISMS Some people believe that the soil should be heated before use to "sterilize" it. This can cause more harm than good. I agree with the practice if you are using your own home-grown compost as an Organic but sterilizing will kill all the beneficial bacteria and other organisms leaving the soil essentially lifeless. Avoid using soil that doesn't have any weeds growing in it. Roadside soils can contain oil, asphalt residue and pestisides. Stay away from beach sand and soils that contain salt and high concentration of other minerals. Kitty litter is okay as long as it hasn't been "used" but stay away from the deodorized types that contain chemicals and dyes. It's better to by calcinated clay. It's also not a good idea to use manure as soil. It can contain straw and undigested organic material that will break down over time and cause soil compaction. Aquarium gravel is usually highly polished - which is bad - or artificially colored, which is worse. If you have a wooded area with mature trees similar to your potted variety, find one of these trees, brush off the top layer of recently fallen material and look for a moist, partly rotted layer beneath. Dig up a couple of handfuls, including the top layer as well, and place it in a container to keep it moist. Make a "soup" when replanting by stirring the material briskly in a bucket of water. Pour the container over the root area for a beneficial "drink."

Keep in mind that soil is a personal thing. What works for you may not work for your neighbor or your email pal from a different temperature zone. Basic soil mixes can help take a lot of the guesswork out of it allowing you to get on with the art of... B O N S A I !!!