How To Make Your Bonsai Trunk Thicker (7 Easy Methods)

A thick trunk enhances the aesthetics of your bonsai and gives support to the entire tree. But growing the trunk perfectly thick isn’t an easy task. Right? If your bonsai trunk is narrow and your goal is to make it thick, you must acknowledge how to make your bonsai trunk thicker. 

Making bonsai trunks thicker requires a lot of growth. So you should pull out the plant from the shallow pot and plant it on the ground or in a large pot for rapid growth. Keep waiting until the trunk reaches the desired thickness. 

That’s not the only way. In this article, we discussed several other common and easy techniques to thick bonsai multiple trunks. We explore the fastest and longest process that’ll help you choose the best one for you.

Let’s start reading!

How To Make Your Bonsai Trunk Thicker
Close up Japanese Bonsai Tree Trunk

How To Make Your Bonsai Trunk Thicker

Before we know how to thicken the bonsai trunk, let’s first understand why you should make a bonsai trunk thicker.

Benefits Of A Thick Bonsai Trunk

A thick bonsai tree trunk is essential to ensure the good health of your tree and the following reasons. 

  • A thick trunk transports enough nutrients and water to the foliage and helps to transfer carbohydrates from leaves to roots
  • Supports bonsai against elements  
  • A thick trunk ensures the longevity of a bonsai tree.

These are the most common three benefits of getting your bonsai trunk thicken. Now, it is time to know the methods to thick trunk bonsai

Method 1: Growing in the Ground

Bonsai trees are full-sized trees. But they are confined in a small pot to restrict their root growth and keep them miniature. So based on this logic, when you remove your tree from the pot and plant it in the ground, the root system will spread and grow as normal. You can do this by following some steps.

  • Step 1

Remove the bonsai plant from the pot and plant it in the ground.

  • Step 2

After planting, wait until the trunk gets its desired thickness.

  • Step 3

When it becomes thick, remove it from the ground and put it again in a shallow pot to stop further growth.

This method can take years to make your bonsai tree thicker. So you can apply this method to fast-growing species like Ficus or Chinese Elm. 

However, planting trees on the ground can cause several problems. If you wish to follow this method, you should have a clear idea about its problems. So, here we like to share the possible issues with the ultimate solution. That’s why, you can easily avoid the problems. Or if the problems arise, you can  identify and solve them. 

  • Lack of Nutrients and Drainage 

If you don’t fertilize your ground’s soil before planting the tree, its growth can be slowed down. Otherwise, if there is a lack of drainage, it can cause root rot and kill your bonsai. 

So before planting the trees, make sure your soil has enough nutrients and drainage.

  • Weather and Temperature 

Every bonsai species requires different weather and temperature. Tropical bonsai trees can’t survive cold winters because they need warm weather and high humidity. So make sure the tree you’re grounding outside can endure the weather throughout the year.

  • Pests & Diseases

Planting your bonsai trees outside in the ground can create high chances for pests and diseases.  You must check the trees regularly, so you can treat them when you notice any potential problem. 

Method 2: Sacrificial Branches

If you don’t want to plant trees in the ground or have limited space to grow a thicker bonsai trunk, the great option is using sacrificial brunch. 

The sacrificial branch method increases a side branch near the bonsai trunk base. When the side branch grows out, the rest of the tree is restricted and pruned. So the sacrificial branch can feed the trunk lots of nutrients. As a result, the nutrients help your bonsai trunk to thicken up.

  • Step 1

Choose the sacrificial branch from any side, but take it from halfway of your bonsai trunk.

  • Step 2

Wire the branch to keep it straight while growing. 

  • Step 3

Prune and restrict the other branches and the rest of the tree from growing.

  • Step 4

Once the trunk is thicker as you want, remove the sacrificial brunch from the bark with a pair of clean concave cutters.

  • Step 5 

Lastly, prune and shape your tree to enhance aesthetics with a thicker bonsai trunk.

The sacrificial branch you choose will be very thick and leave a big scar on the tree while removing it. And it may take a few years to heal the scar. So try to grow the sacrificial branch in the back of the tree that no one notices and doesn’t affect aesthetic beauty.

This method works best for Pine. But sacrificing lower branches will not be suitable for it. So, in that case, you should focus on Pine’s apical dominance.

However, the Sacrificial branch is an excellent way to develop a tapered trunk as it adds girth to the trunk under the attachment point while growing. 

Method 3: Trunk Merging

If you’re looking for the fastest way to make your bonsai trunk thicker, trunk merging is an excellent process. This method is also called trunk fusion because it creates an illusion of becoming one tree. You’ll get the best result by applying trunk merging for the fastest-growing species like Chinese Elm or Ficus.

Though it’s not a traditional way to grow a thick trunk, gardeners like it because it takes much less time than a traditional one. However, you can’t do this on an existing bonsai. 

  • Step 1

You need to tie multiple saplings with a light rope, and connect the saplings as tight as possible. 

  • Step 2

When you keep them tied for a few months, the trees will begin to merge eventually. 

The trunk merging process will give you enormous control over the tree design. You can plan your desired tree size and begin tapering early. 

Despite it being the fastest-growing, this process has some disadvantages too. If any sapling dies during the merging process, it leaves a gap in the trunk and takes more time for fusion. Then how can you fill the gap? In this case, you need to plant a few seedlings to replace the dead tree. 

Keep in mind that you must cut the root from a parent tree; otherwise, your saplings will merge with different characteristics. As a result, each side of the tree will show different types of foliage, and it will directly ruin the aesthetics of your bonsai tree.

Besides, make sure all saplings are getting light, air, water, and nutrients adequately to grow healthy. If one of your saplings dominates the resources, the others can die off very soon.

If you’re a beginner bonsai enthusiast, this method seems to be difficult for you. However, it’s a great way to show a fast result without scarring on the trunk.

Method 4: Cut Back the Trunk

Cutting the trunk is an excellent method to taper a thick trunk nicely. It works best for tree planting on the ground, because ground trees grow fast. You can cut the trunk down to get it thicker and tapered. Follow the steps below to cut back your bonsai trunk.

  • Step 1

Make the first cut of the trunk at the point where it reaches desired thickness. It may be one-third of your desired height for a bonsai tree. After the first cut, let the bonsai trunk grow again.

  • Step 2

Next, you’ll notice a new branch will grow after the first cut. Let it grow out to the desired thickness. At the same time, prune the other branches and buds so that the new leader can get many nutrients and encourage them to grow.

  • Step 3

When the new leads of the trunk reach the right thickness, make the second cut of your trunk.

  • Step 4

Repeat this process until you get the desired thicker tapered trunk. You may need to do 3 significant cuts to get the realistic look. But keep patience as this method takes a few years to give you a thick, curved, and gently tapered trunk.

The downside in this method is making prominent scars on the bonsai through cutting back the trunk leaves. It takes several years to heal the wound. If you want to do a broom-style design or establish a formal upright, this method can be challenging to do so. 

Method 5: Split The Trunk

Splitting the bonsai trunk from the base is the quickest way to make the trunk thicker. This technique almost shows instant results. But it would be best if you used this on the trees that can tolerate the procedure.

You can implement this method on trees that can bear traumatic injury and are healthy and vigorous such as Chinese Elms, Juniper, and Boxwood. Applying this procedure at the beginning of the growing season will help you get the best result.

  • Step 1

Pull the bonsai tree from the small pot and wash away the root to remove the soil. After that, hold it upside down.

  • Step 2

Take a rotary tool or saw,  trunk splitter, and start splitting the trunk down the middle to the halfway point.

  • Step 3

Now re-transplant the tree in the pot and use wires or wood wedges to remain the two halves of the trunk separate from each other.

  • Step 4

Now let the trunk heal. The healing process may take years, and you can speed up this process by potting the tree into a large pot. Finally, you’ll see an immediate thicker illusion of the trunk in front of you.

Method 6: Bend The Trunk

Follow this superb method if you’re finding a technique that won’t leave any large scars while making bonsai trunks thicker. This method basically focuses on the movement and flow of the tree.

  • Step 1

Take a young tree sapling because a thicker trunk is tough to bend.

  • Step 2

Next, take wire pieces to bend the main trunk downwards. Then bend the vertical branches upwards. 

Eventually, the side branches will grow out less thick than the main trunk, and it forms in a nice tapered look. Remember, bending should be done at the beginning of the growing season to get an outcome.

Method 7: Induce Swelling by Tourniquet

There is an ancient Japanese method used by most of the highly respected Japanese bonsai masters. You’ll need a wire tourniquet to complete this process.

Place the wire tourniquet around the base of the tree where you intend to induce swelling. It effectively creates a great tapered trunk. With this method, you can tape the trees like Chinese Elm that aren’t naturally tapered.

Applying this process to the fast-growing species will take only a single growing season to make the trunk thick. This method can grant you a noticeable quick result but leaves a deep scar of tourniquets. However, take caution while doing it; otherwise, the wounds will remain permanent. 

So, now we have covered up all the possible methods on; how to thicken bonsai branches and trunks. 

Quick Tips

  • Try to choose specific species for each method to adjust the process as all kinds of plants can’t go through the same procedure.
  • As planting trees outside can risk several problems, you can consider transplanting the tree in a large pot. This process not only saves you from different obstacles but also helps to control the rapid growth of the growing season.
  • For smooth tapering, you can grow several branches as a sacrificial branch. First, select the higher branches and eventually move to the lower branches. 


Thick trunks are the ultimate goal of every bonsai gardener, and achieving this will make you feel proud. Fortunately, we shared with you several methods. So learning about how to make your bonsai trunk thicker will definitely help you in this regard. 

Hopefully, you can keep proper patience and dedication to meet your goal following our information. No more today. If you want to share any experience relating to bonsai, do comment and let us know. 

Best of luck! 

Leave a Comment