I've watched the threads on bonsai soils with interest as I have just
given a talk on materials for growing bonsai to my local club. Please
take the following thoughts with the required "grain of salt" as I've
only been doing bonsai for about 5 years.

First, the only consistent I've found in discussions of bonsai soil is
that it must be free draining. If it isn't, take it out and start over.

Second, the whole subject of soil is so complex with interrelated
factors that there doesn't seem to be any reasonable possibility that a
"cook-book" statement of what is bonsai soil is possible. You'll have
to look over the possibilities and make your best guess as to what soil
will work for you and your condition. Sorry about that but that appears
to be the facts of bonsai life. Guess, try, correct seems to be the
only way you can find out. The result of this is that your mistakes
will not survive. Try to keep is simple and keep records.

Third, since you are experimenting, work with cheap materials. I'm
still in my "kill a weed" phase so I dig a lot of landscape material
which I think will have good potential. If I guess wrong, the failure
goes out with the yard trimmings. The successes will eventually go into
bonsai pots and MAY eventually become something interesting.

Now, bonsai soil materials. I keep screened (mostly) material separate
and then mix for the specific plant. As a result, I have multiple
buckets and cans in my potting shed. Here's what I have and why:

Perlite - It's white, ugly and floats. It's also very cheap and holds
moisture while being fast draining. I use it as part of mixes for newly
collected plants and those still needing much development. In these
cases, the material works very well. I don't think I'll ever use it in
a bonsai pot but I can't do without it for collected material which will
be totally bare-rooted when potted into training pots for style
development. I get it at my local big-box store, Home Depot, although
possibly obtainable from your nursery supplier in small quantities.

Vermiculite - Pretty much the same as perlite except not so ugly and
white and doesn't seem to float. Usable for smaller collected material
and perhaps for very small bonsai and companion plants. Some of these
smaller pots may actually have vermiculite as a component if I
anticipate annual re-potting. If the mix seems to break down too fast,
then I discontinue it for that plant at the next re-pot. Also obtained
at a big-box store or nursery.

Peat moss (or Moss peat for the European contingent) - Dangerous stuff
which I only use for acid- and moisture-loving plants, specifically,
azaleas. It is very fine and I do not sift it but I also only use a
small amount as a mix component, say 5%-10%. Again, a big-box store or
nursery purchase.

Now the main stuff:

Baked Clay - This is the Turface, Terragreen, Mule Mix, etc. stuff. It
drains very well but holds moisture as the water does soak into the
individual particles. I use it as one of two main, inorganic,
components. If I have a plant which likes water, then this is the main
component. I get it at an auto parts store. I go in and ask for a bag
of "oil-dri". Since Turface (I think, although it might be Terragreen)
is made by the Oil-Dri Corporation, the stuff is usually the same as the
bakes clay products everyone is recommended. There is one caveat, the
stuff is also used as kitty litter. Kitty litter is NOT the same,
although baked clay can be used for kitty litter. How to I tell the
difference? I screen some (to remove the fines) and put it in a jar of
water. After a few days, the kitty litter stuff turns to mush, suitable
only for muck on slab plantings. If it hasn't turned to mush in a few
weeks, then it's baked hard. I have yet to have a bag I've gotten from
an auto parts store fail this test. Since it is used to soak up oil on
a garage floor, the usual auto parts store doesn't want it to become
mush either. If it did, then the garage people couldn't sweep it up and
would not deal with that auto parts store any more. Here is one of the
"grain of salt" points. I have not been doing this long enough to have
a pot which has not been re-potted for 5-10 years. Some pines may have
this long a re-potting schedule.

Pea Gravel - The other inorganic component, screened to eliminate
anything over 1/4" and fines. I use this where the plant wants dryer
soil. I always want some moisture holding component, so this is usually
used in conjunction with the baked clay. I get this from my local
nursery. I check the bag to see that most of the gravel is less than
1/4".

Shredded Bark - The organic component. This is the tough one for me. I
use to get bags of "organic soil conditioner" but haven't seen this
recently. What I'm now doing is to take pine bark mulch and put it
through a garden shredder. Since this device seems to be hard to come
by, I can not recommend any replacement. Perhaps your local big box
store or nursery can order the "organic soil conditioner" for you. Good
luck on this component and let me know what you've found as I'm tired of
shredding bark. Either way, screen the end result.

Now that you've got stuff, mix it in proportion depending on your
plant's individual needs. I use Naka's book and Herb Gustafson's to get
an initial mix ratio. The books which tell me to use "loam" or 'garden
soil" are not a big help to me as essentially I'm using a "soil-less"
mix.

Good luck and have fun - jay

Jay Beckenbach - Melrose, FL - Zone 8b/9a -


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