In part two, we discussed three main types of constraints that we use to develop bonsai. In part three we will begin to dive into the choices we make when applying those constraints. This is necessarily high level – an entire book could be written on this very topic. I will later follow up with examples from my own trees in other posts.

Understand your variables – the devil’s in the details

Like making a good shot of espresso, there are many variables that come into play when developing bonsai that might not be initially obvious.

With espresso, some of the things that matter are the way you roast the beans, the way you grind the beans, the way you tamp down the coffee in the portafilter, the temperature of the brewing water, and even the temperature of the cup you put the espresso in. Juggling it all to get the perfect shot of espresso is a definite skill.

If you make an espresso without understanding how each of those variables changes things, you’ll likely get a mediocre cup of coffee. Similarly, applying bonsai techniques haphazardly without a strategy and without understanding how each of the constraints you employ affects development may get you nothing but ugly, under-developed trees.

Creative application of constraints

In the last post we discussed constraints. When you constrain a tree, it has to adapt if it is going to survive. When roots are cut or restricted, the tree adapts. When a branch is cut, the tree seeks to grow a new branch from another location. Some trees do this better and more predictably than others, but all trees will in some fashion try to correct for damage that has been done to them.

Each time damage occurs, and the tree heals, it leaves behind a scar of some sort, some large, some small. Those scars, when artfully created, and artfully used, can give a tremendous sense of age and weariness to a tree. They also contribute a sense of scale when done well.

Striving for scale

Back to the topic of scale. What we’re ultimately after in a good bonsai is a sense of scale. A properly developed tree with a good sense of scaled tree looks very much like a full-scale tree.

One of the key ways we achieve that is by developing good taper. A tree with good taper starts thick at the bottom and branches gradually become thinner as it moves up and outward. There’s a physiological reason why this happens with full-scale trees, and people see real trees around all the time that do this.

So it should go without saying that if you can reproduce this well in miniature form, then you are well on your way to creating a natural looking miniature tree.

But miniature trees don’t tend to do this without a little bit (let’s be honest, a lot) of help from us. They don’t know they’re being scaled down, they just react to constraints, and keep striving to become full scale trees. It’s up to us to make judicious use of constraints to artfully create a tree that works.

There are many other elements that contribute to scale that I will delve into in future posts.

Pump the brakes

Left to their own devices, trees will grow into larger trees. You could take a perfectly scaled, perfectly manicured bonsai tree, plant it in the ground, and within a season or two, all those years of development would probably be ruined or at least severely set back. So unless we have a good reason, we don’t let that happen, and we use a constraint to slow things down.



Here are some things that can directly and immediately slow down growth:



Pruning branches. Cutting a branch kicks off a compartmentalization and healing process. You can take a branch that if left along would double in thickness in a few weeks, and with one snip of the shears, you slow that down for months.

Cutting a branch kicks off a compartmentalization and healing process. You can take a branch that if left along would double in thickness in a few weeks, and with one snip of the shears, you slow that down for months. Defoliating the tree. Not something we recommend doing very often, but there is a time and place. When you defoliate, the tree is significantly weakened, and a massive back budding process is triggered. This is something you only do on very healthy trees of appropriate species.

Not something we recommend doing very often, but there is a time and place. When you defoliate, the tree is significantly weakened, and a massive back budding process is triggered. This is something you only do on very healthy trees of appropriate species. Repotting. When you repot, you provide an opportunity for renewed growth, but for a time, you slow the tree down. How much you slow things down depends on how extensively you prune the roots when you re-pot. A light re-pot or slip potting to a larger pot may not slow things down much at all. Extensively pruning the roots can take a little while for the tree to recover, and it may grow slower that season.

When you repot, you provide an opportunity for renewed growth, but for a time, you slow the tree down. How much you slow things down depends on how extensively you prune the roots when you re-pot. A light re-pot or slip potting to a larger pot may not slow things down much at all. Extensively pruning the roots can take a little while for the tree to recover, and it may grow slower that season. Choosing a smaller pot. The size of the pot itself is a growth regulator. A tree can only grow so much in a tiny bonsai pot. Doing a heavy re-pot, with lots of root work, will most definitely slow a tree down while it recovers it’s root mass. In a year where you do significant root work, the tree may appear to be at a standstill for the season, or it may grow a bit slower than usual.

Step on the gas

Sometimes we need to lighten up on the constraints and let the tree stretch out. In fact, alternating between constraints and growth is often what makes a tree interesting to look at.

Slowing down growth is easy, but speeding it up happens mostly by loosening up on the constraints and letting the tree do it’s own thing for a while. Ultimately, if you’ve set everything up correctly, you’re at the mercy of the trees growth rate. This is where patience comes in.

Things that speed up growth & development:

Increasing pot size. Increasing pot size provides more room for the tree to stretch out. This, in turn, will eventually lead to faster development, provided that you actually let your tree grow.

Increasing pot size provides more room for the tree to stretch out. This, in turn, will eventually lead to faster development, provided that you actually let your tree grow. Let the dominant branches run. When evaluating a tree, look for your dominant branches – those are the ones that are going to take off first. Sometimes you want that, sometimes you don’t. But if they’re at the top of a trunk line that you want to thicken up, pruning them can be extremely counter-productive.

When evaluating a tree, look for your dominant branches – those are the ones that are going to take off first. Sometimes you want that, sometimes you don’t. But if they’re at the top of a trunk line that you want to thicken up, pruning them can be extremely counter-productive. Providing proper water and sunlight. If you’re not giving your tree the amount of water and sunlight it needs, it will not grow at the optimal rate. Outdoor trees generally grow way faster than indoor trees for this reason.

If you’re not giving your tree the amount of water and sunlight it needs, it will not grow at the optimal rate. Outdoor trees generally grow way faster than indoor trees for this reason. Fertilize regularly. Applying fertilizer throughout the season ensures that the plant has the nutrients it needs to maximize growth.

Parting thoughts on constraints

Each season, it’s important to evaluate your trees and decide what your development goals are for the year, with a thought towards the next 5-10. Only then should you decide what constraints to apply for the season.

A lot of people starting out can see only see what’s staring them in the face. They’ll try and put things in bonsai pots too soon, and they’ll try to make branches work as part of the design that an experienced eye sees as an obvious sacrifice branch.



When it comes down to it, you need to decide in a variety of situations if it’s time to tap the brakes, or step on the gas.

In future posts, I’ll be referring back to this series regularly, with specific examples from my own collection to demonstrate what I mean. I have examples of trees in a variety of development stages, and I’ll do my best to explain my development strategies and thought process for different situations.

Future posts will have pictures and diagrams to illustrate all these points, but I can safely say that this 3-part article sums up much of my bonsai development philosophy at a very high level. Once you learn to apply constraints effectively and judiciously, you almost can’t help but end up with nice trees over time.