This article originaly appeared in the Bonsai Society of San Fransico’s newsletter: Fog City Bonsai February 2007 Issue
You would think that, after nearly ten years of doing bonsai, I would have accumulated some wisdom about the subject. Perhaps I have, but I feel more like I’m just beginning. However, I did pick up a few nuggets that may be useful to other beginners. How did I learn these things? Much of it came by learning from the more experienced members of the Bonsai Society of San Francisco, which I joined two years ago. Incidentally, call it “BONE-sigh”, not “banzai”. Banzai! is a Japanese battle cry, used to summon up courage. What we need is not so much courage as patience and wisdom.
Pick the right tree
Choosing a suitable tree won’t guarantee a great bonsai, but choosing an inadequate one will guarantee the bonsai will never be great. If the tree you choose does not have “good bones”, it is forever doomed to second class citizenship. Most of my earlier bonsai were like that.
How a bonsai is grown can overcome some deficiencies, but very few in the trunk. The trunk is all important. Bonsai can be grown from skinny whips of saplings, but more money spent on a bigger tree to begin with will put you several years ahead at the beginning. In nursery plants, the best trees are the ones that have been grown specifically for bonsai. The older and fatter, the better. Choose one expensive six-foot tree in a big pot rather than three skinny ones in small pots.
Look for three things. (1) Nebari are the roots that are or will be exposed. Use your fingers to scratch next to the trunk so you can get an idea what these roots look like. Choose a tree whose roots you can see, roots that taper out from the trunk, either at or just below the surface. (2) Look for a trunk that is fattest at soil level, tapering evenly to smaller diameter above that. (3) Buy the tree with interesting bends in the trunk, unless you want a straight, formal upright style, such as with a redwood. It is difficult to make new angles in tree trunks that are very large, but is quite possible in smaller trees and in most branches. Sharp angles can be obtained by removing the entire trunk above a prominent branch, and making that branch into the new trunk. And the trunk can be curved in various ways if it is not too thick. To my eye, some of the most interesting have a sharp turn or curve just above soil level. Virtually no good ones have long sections of trunk or branch that look like a dowel. Don’t worry too much about how branches look because you will grow the tree to look the way you want it to look, which often means cutting off the top twothirds. In fact, if you buy a large nursery tree grown for bonsai, you will probably have far too many branches. This gives you the opportunity to cut away all but those that will make the best design.
Make good roots
Just about everyone who doesn’t grow bonsai thinks they are made by starving them and chopping off most of the roots. In fact, very nearly the opposite is true. Bonsai must have a thriving root system, must grow in a medium that provides conditions for maximum growth, and must be frequently watered and fertilized. True, we do chop off some roots. We remove the large roots that provide stability for the tree in the wild, especially those that grow straight down. In the bonsai pot, we substitute for that loss of stability by using wire to anchor the tree snugly in its pot.
So, do remove thick support roots when you repot your tree, but keep most of the network of fine feeder roots. The exception is the feeder roots that are so long that they would hang over the edge of the pot if stretched out. There may be a lot of these on a tree that has not been repotted for several years. Cut these roots to fit the limits of the pot when you remove the fat roots.
Fertilize and water enough
Growers who know both Japanese and American bonsai say that Americans rarely fertilize their trees adequately. As a rough rule of thumb, most trees should be fertilized year-round (with some exceptions) about every two weeks. A simple way to do that is to fertilize on the first and fifteenth of each month. It is possible to damage trees with too much fertilizer, but if you use an organic low-level fertilizer and go a bit easy this is unlikely. Frequency of fertilizing is important; lots of fertilizer is not. You will see boxes of fertilizer with numbers like 8-6-4, or 0-10-10. Choosing numbers of 10 or below will help keep you out of trouble. These are the “N-P-K” numbers, which are the chemical symbols for the major nutrients, nitrogen, phosphorus, and potassium. Nitrogen makes green leaves, and the others nourish roots and blossoms. A good dose of nitrogen is needed when green growth should be encouraged, such as springtime. The exception is flowering plants such as wisteria. Here, nitrogen should be withheld until blooming is finished. 0-10-10 may be used instead, and should be used to aid root growth on most bonsai during the San Francisco “winter” (a slightly humorous term to those of us from colder climes).
Besides boxed fertilizer, there are numerous recipes for homemade fertilizers. Small pellets of various types are also available, as are soluble fertilizers. The pellets are usually low-level organic fertilizers that don’t cause problems. Soluble fertilizers are diluted to low levels of strength and reach the roots immediately, but don’t last long.
The importance of the planting medium and watering should also be mentioned. In San Francisco, for several reasons, the best planting medium is one that is relatively coarse and that does not become packed and hard, like clay. This allows the fine roots to develop more easily and allows air to reach them. But it has virtually no fertilizing power and does not hold water for very long, so it is important to fertilize properly and to water often enough. On hot sunny days your trees may need to be watered twice a day. On days that are cooler and less sunny, water only when the soil has started to become dry, which may vary from tree to tree.
Fill out the foliage
If you have made it possible for the roots to function at their best, you will have gone a long way toward providing rich foliage. But there are other things that will also help.
The concept of “back-budding” is crucial. Back-buds are new growth that pops out, particularly during the strong spring growing season, closer to the trunk, rather than at the ends of branches. We can encourage such growth by cutting off the far ends of branches, especially branches that have become long and “leggy”. It is important to leave some green growth at the end of the newly shortened branch so that sap will still be drawn through the branch. The branch will then have more than enough nutrients flowing into it, which it will often turn into new growth in the form of back-buds that fill out to make the branch look healthy and full.
Foliage growing in the shade of branches above, or shaded by heavy growth closer to the ends of branches, is often anemic and unhealthy looking. This is overcome by removing unnecessary branches so more of the trunk is visible, by positioning branches so that they don’t shade those below, by removing excessive growth at tips, and by removing dead material, especially during fall “cleanout”. The one-twothree, side-rear-front method of positioning branches on new trees in fact helps prevent upper branches from becoming unwanted parasols for the lower ones.
There is a right season
It is tempting to do work that needs to be done when you see it. Yielding to that temptation is how I lost more than one tree. It is far better to wait until the proper season. For example, most trees are best repotted just when they begin to wake up in early spring. In San Francisco repotting time begins in January.
There are occasions when you must repot at the wrong time. You may be successful, as I was when I collected an old rosemary bush in hot weather, but if it’s not really necessary you may risk losing your tree by repotting at that time. Likewise, there are best times for pruning, for fertilizing heavily, for defoliating and decandling, and for most other procedures. Sometimes you can get away with it, but cultivating patience will give you better results in the long run.
The last thing I will mention about what my ten years of bonsai has taught me is that each type of tree is different. Learn what each tree needs to make it flourish and look like a bonsai-or to follow John Naka’s advice, to make your bonsai look like a tree. An important part of that is to understand when and how to do what. For example, small needles are obtained on black pines, not by giving them a haircut, but by removing the candles, the up-going new spring growth that looks like green candles. It is important to do this in June or July in SF, which gives the tree time to develop new buds, which then turn into candles. But they don’t have enough time to become long needles before winter arrives, so instead they become short ones, just what we want.
Like people, every tree has quirks and habits, and much of our success depends on learning what these are and how to manipulate them while giving the tree the things it needs to thrive.
Don’t plan to finish your bonsai
Bonsai is what you do, not something you finish. A bonsai is only “done” when it dies. Meantime, you will experience many wonderful and frustrating hours learning how to give a tree what it needs to become a creation that touches the heart, the mark of a successful bonsai. Every year your bonsai will be different, and every year you will learn something new. Perhaps these hints will help the less experienced bonsai enthusiast to avoid some of the errors I made in my first decade. In the future I might even write again to tell about things I learned during my second ten years as a bonsai beginner.