Let's Talk Soil

By Thomas J.

One of the biggest discussions in the world of bonsai, is the one concerning the soil mix that we use to grow our trees in. Seems everyone has their own special mix, and the next guys just isn't good enough. This could be awful confusing to the beginner who is wanting to do everything right so as not to be responsible for too many dead trees if he can help it.

So many articles have been written for bonsai publications and online forum discussions, that there really isn't anything more I could add to make a difference. I know what works for my trees and I won't try and convince anyone that mine is the mix that everyone should be using. Rather than that, I would like to just say a few words about the basics of soil composition for the beginners out there.

One thing most bonsai growers will agree on, is that whatever type of mix you use, it needs to be well draining. And of course the reason for this is to eliminate the possibility of root rot. For this reason you should be using a soil mixture which most people would call coarse or gritty. Some of the ingredients for this type of soil mix might consist of sand, which will need to be a specific size and not your playbox type. Here's a picture of the correct type sand to use, which should be grit#00 or #0. This picture shows #00 on the left and #1 on the right, which would be too small a grit to use because it will probably compact on you, and that's not what you want to have happen.

Crushed lava is another componet that people like to use and here is a picture of it.

Calcined clay, pumice, a patented item known as Turface, or another highly acclaimed product from Japan known as Akadama, are all used by bonsai enthusiasts.

Now which of these materials is used together is where a lot of the controversy begins. I've talked to a few highly respected bonsai artists, and most of them like to use the Akadama- pumice mix with nothing more addded except maybe a little crushed lava thrown in. When I say nothing more added, I mean no organics added to the mixture. Organics in this case is referred to as landscapers mix, which usually consists of pine bark mulch with a bit of sphagum moss and maybe a touch of perlite. Some people don't like to spend the extra money on Akadama since it is an imported item, and for this reason will not use this type of mix. Others say they can see no difference from that and the standard clay-sand-organic mix.

The landscapers mix should be sifted to get out both the very fine parts which has a consistency of powder almost, and the very large pieces which are of no use in the mix. Here is a picture of the large pieces sifted out,

And a picture of the sifted material ready to be mixed in with the other components of choice.

A good set of sifting screens should be purchased which will make the job a lot easier and enjoyable.

The health of your trees, excluding insect infestation, will really come down to the type of soil mix you have and whether or not your trees are taking up sufficient water, or whether they are drowning in water. The soil mix should also be helpful when you fertilize. There is a purpose for using these specific ingredients, and this link will point you to an article that should really be helpful to you in explaining this.

http://www.evergreengardenworks.com/soils.htm

(Link Used with the kind permission of Brent from evergreengardenworks.com)

Well after reading all that, I would just like to sum this article up by saying this: since your bonsai soil mix will not really be a soil but will actually be soiless, it is imperative that you fertilize, and that you do it often.

Fertilization is another aspect of bonsai where many people will have differing opinions on which fertilizer to use and which is best. Again, I won't give my opinion on this, only a few facts to help you decide.

Many people, myself included, like to use mainly organic fertilizers. Organic fertilizers are slow release and allow the plant somewhat of a continual feeding this way. Just like the soil ingredients that have a specific purpose, so do the different types of organic fertilizers. For instance bone meal would be to help the root system. Fish emulsion is a good source of nitrogen. The only thing wrong with using these components by themselves, is that they have no trace minerals to dispense to the plant. All plants need trace minerals for optimum health, kind of like taking a multi vitaminn pill.

One mineral that a good healthy plant will need and won't be found in your basic bonsai soil mix is Magnesium. This minerals function in plants is in the manufacture of chlorophyll. I'm sure everyone knows the necessity of chlorophyll in the life of a plant. For this reason it is a good idea to give your trees a shot of chemical fertilizer every once in a while if your doing mainly organic fertilizing, because chemical fertilizers come with these trace minerals.

Now that's not to say that there aren't any organic fertilizers out there with these trace minerals added also. A good brand that many bonsai enthusiasts use is a product called Bio-Gold which is a fertilizer made in Japan. This is a product which can be ordered right here at Dallas Bonsai Gardens and should meet all of the needs any bonsai tree should need.

Note: Dallas Bonsai Gardens will soon be listing all the elements in English on a new fertilizer product from Japan. As most fertilizers from Japan are in Japanese, including the Bio Gold, this new product will be translated in English so that you will know exactly what you are getting.

If your working with any type of junipers in your collection, the trace minerals are a must. As I noted in my article on "Having Fun With The Juniper Procumbens" , if your starting to get yellow foliage even though your tree is in full sun, it's probably because it's lacking the needed trace minerals. Here is a picture of the kind of rich and green foliage you should be getting if you have the right kind of soil mix and are applying fertilizer often.

You may decide to use only chemical fertilizers on your trees, and that's ok too. Most chemical fertilizers come with an even proportion of Nitrogen, Phosphorus, and Potassium to meet the plants basic requirements, plus added minerals.

Well I hope you'll take some time and really read the article I've linked for you because repotting time is right around the corner. Many beginners dread repotting time when actually it should be something you look forward to. What better way of seeing what your many months of laboring by watering and fertilizing has accomplished, than by getting right in there and seeing for yourself. For those of you who feel unsure about your soil mix, or are hesitant to do your first repotting, maybe you could ask a fellow club member for help. All in all though, repotting is a necessary task in bonsai and your trees will love it also. Good luck with your soil mixes, and above all, have fun doing Bonsai.

Note: Next months article will be on repotting for beginners.