What Is The Difference Between Winter Pruning And Summer Pruning On A Bonsai Tree?

You have probably heard people talking about summer or winter pruning of their bonsai and it can be a little unclear what the differences are.

They can look similar, but they are actually done for very different reasons. Both types of pruning will be needed over the life of your bonsai and a combination of the two will help your tree develop into the tree that you want.

Both Type Of Pruning Are The Same, But Different

From a far the two types of pruning can looks the same, but they are different.

The confusing thing is that the same pruning principles are used, but the reasons for using them and what is trying to be achieved is different.

Winter pruning is more for cleaning up the tree and getting it ready for spring, and summer pruning is more about keeping the tree on track with your overall goals, but I will go through both types of pruning now in more detail, so you can get a better understanding of the subtle differences and the reasons behind each approach. 

(You can read more about – How To Prune A Bonsai Tree – A Beginners Guide)

Why Do We Prune Bonsai In the Winter?

When we say “winter” we really mean the very end of winter, just before the tree wakes up and spring starts.

This is an ideal time to prune as the tree is still dormant, but it will be growing soon. The bulk of the trees energy will be stored down in the roots at this time, so you can basically hack away at the tree and it will not affect its vigour as we are not removing any of its energy.

The fact that it will be growing again soon also means that it is going to start healing itself pretty quickly after we have done our work. This is why we don’t prune in the middle of winter, as if it did it, it then it would not be growing and healing its self, since it’s dormant at this time. Having a tree just sat there, not healing is not ideal and it could allow all sorts of infections to get into the wounds.

We also get to remove sections of the tree that we do not want, which is usually the long growth that was put on during the previous summer. All of the shoots will have elongated and you may also find they are crossing, or that there is multiple shoot in one area, which can cause swelling.

This is type of growth is great for the trees health, but it doesn’t look great as bonsai. Coming in at this time of year and removing all this type of growth, or just shortening it back allows us to make structural decisions as well as reduce the size of the tree, that will both help us progress the tree aesthetically as bonsai.

This is also made easier at this time of year as there are no leaves in the way.  

Removing sections of the tree that we do not want also means we are not wasting the spring energy on parts of the tree we do not want.

The tree is about to wake up and start pushing its energy back into the tree. If we did not prune the tree first …then the energy would also be going into these unwanted sections too. This would be a waste of energy, as we would be allowing parts of the tree we don’t want to grow.

Pruning in late winter really sets the tree up for spring and allows all of the energy to only go to those areas we actually want to keep which should allow them to develop faster and stronger than they would have previously. 

Why Do We Prune Bonsai In The Summer

When we prune a tree during the summer it is usually to manage the growth and to stop things from getting too out of control.

Trees can easily put a lot of growth on and while this is great if you are trying to develop your tree, it is not ideal in a tree you are trying to refine. Not only will pruning in the summer knock some vigour out of the tree, but it actually has the added bonus of creating more ramification, which is exactly what you want when you are trying to ramify a tree. 

Every time you prune, the branch you cut should shoot back at least 2 new buds, allowing your branch to now divide into two. If you keep doing this over time, you will eventually end up with a very ramified branch.

Summer pruning can also keep the tree healthy. A tree that is growing really strongly can put a lot of strain on the small root system and the tree can struggle to keep up with the demands, especially if it has been repotted recently. Pruning the tree back can put things back in balance and the roots can better support the foliage after pruning. 

Of course the more leaves there are, the more they can send energy down to grow more roots, so it really is a balance. If you prune too early you are actually going to limit the root development, but if you wait too long then there may be too many leaves for the roots to support. You will have to watch your tree carefully to see how it is growing and if it is struggling to support the foliage or not.

Defoliation

You might also prune your tree in the summer by just removing the leaves, which is known as defoliation. We do this to allow light into the centre of the tree, which will keep any inner buds healthy.

However, this process also knocks a lot of vigour out of the tree, meaning it slows its growth down. The leaves will grow back, but they will actually be small, which makes a great technique for refining a tree.   

(You can read more about – What Is Defoliation In Bonsai?)

Both Types Of Pruning Are Needed

You will need both types of pruning through your trees life, although you may find that sometimes you do not need to use both in the same season.

This will really depend on your goals and also how well you tree is growing, but if you feel it is appropriate, you can use both during a growing season if you want to.

I have generally found that when I am developing a tree I just prune it in winter; I let it grow unchecked all year and prune it just before spring to clean up anything I don’t want and to stop any problems from forming.

If I am then moving into the refinement stage, I usually prune in winter and summer …often multiple times in the summer if the tree is really healthy and strong. The trees I grow under grow lights get this treatment as their growth rate is really impressive.

(You can read more about – What Are The Different Types Of Pruning You Can Do On A Bonsai?)

Conclusion

Hopefully you can see now that while winter and summer pruning may look very similar, it is actually done for very different reasons.

Both types of pruning are going to play their part in your trees journey as a bonsai and you should be considering both when the time is right and the tree is healthy enough

(You can read more about – How Can You Tell If Your Bonsai Tree Needs Pruned?)