That’s a really big, fancy word that sounds like something that you might do after too many beers. But what it really describes is the process of splitting in two – as in a branch that forks into two branches. We are more familiar with the word ramification – a branched structure – and its secondary meaning - the result of an action or decision. Put those two together and you have bonsai in a nutshell. We make a decision every time the scissors click together. But how do we make those decisions? Those pruning decisions are most critical on deciduous trees, and now is a great time of year to make them. Notice the “Bi” in bifurcation, as in bicycle –just two wheels. Just two. Not three, not more. So that’s an easy way to remember how to prune our deciduous bonsai. The trees have made it through winter and our latest snowstorm and are ready to go for spring. The leaves of fall are long gone, so we can easily see the structure in our trees. If you were diligent at pinching and pruning through last spring and summer, you are perfectly set up to do some pruning. Now that we have grown all of that ramification, it’s time to take stock and see what’s usable and what’s not. Not everything grew the way we planned – it might have grown too long, in the wrong direction, or too large in diameter. So let’s take a look at how to handle these conditions.
Generally speaking, we always want to cut back to just two branches at any one node or junction. This includes the trunk too. So you might end up with a trunk and a branch, a large branch and a small one, or just two equal sized branches. If you have more than two at any location you will get an unsightly swelling and may have to eventually cut it off. So remember that prefix – “Bi.” Make sure to leave enough healthy buds. On a beech I have no problem cutting back to a single bud in the middle of winter, but on a maple I am more conservative, leaving two buds. Then I prune again to just one bud if it needs it in late spring, after passing the winter cold. Leave more buds for fine branched species like elm and zelkova. Ideally I would end up with two buds on every branch, but it just doesn’t always work that way.
The first place to start is to identify the overall outline or silhouette of the tree. Are your trees there yet? Do you have a plan for them? More than likely you have some trees that are approaching their ideal size and structure. Once you have identified the shape that you are trying to achieve, prune anything that protrudes beyond that outline. If you have an area that is too short, make sure to leave more buds, and length to the branch. This might include all or more of the branch than you might usually leave. Allow the branch to grow out and thicken if needed and reevaluate next year. Make sure to balance the strength of branches too. I take beeches down to one bud in the crown, which are usually much larger than those on the lower part of the tree. Then I leave two on the lower parts, and maybe more on the interior where it is weakest.
Next, cut anything that goes back towards the middle of the tree. Be ruthless. It will be much better in the long run. Remember that the last bud you leave is the direction the branch will head next spring. This means that you may have to leave one more bud, or take one more depending on the situation. Don’t leave two buds that are facing each other and will cross oncethey start growing. Cut anything growing straight up or straight down. These are not usable,
unless you are desperate and can wire them into position.
Branches that have too long of internodes are pretty easy to identify. The distance between nodes should get shorter as you move out to the tips of the branches. The actual length is going to vary with the size and the species of the tree. The size and structure of my large beeches is completely different than the shohin maples. Everything must be in scale and proportion. When cutting back make sure that you have a live, active bud to replace what you are cutting. Sometimes this means cutting clear back to the node that it started growing from last year. But if the branch is too long between nodes for the place they occur in the tree, they will never get shorter. Better to bite the bullet now than to have to cut more off in the future.
Now comes the harder part – both to spot, and to carry out emotionally. As you are pruning you may start to notice branches that have grown stronger than others, even though they are on the same main branch. This occurs no matter how many times you have pinched and pruned throughout the year. Since most of our trees are very apically dominant, these branches on steroids usually occur in the crown of the tree. It may have several twists and turns, but no real taper to it. It may be a great branch, and you may have been growing it for years. But it will only continue to get stronger and spoil the balanced ramification that you seek. Find a place that you can cut back to a live bud or smaller branch. You will see an instant improvement and the tree will look finer and more detailed.
And finally, make sure to leave lots of healthy buds on the tree. You might go through the checklist above and end up with nothing. That’s not the point. We need to keep a healthy amount of foliage on the tree to keep it active and strong. If you need to make a really big cut, do it later in the spring when the tree is going full speed and has time and resources to recover.
Happy pruning! Scott