Bonsai maintenance pruning: where to cut and what to leave

You're standing in front of your bonsai, watching a shoot that has grown well beyond the outline of the canopy. You already have the shears in hand, but a doubt holds you back: is this the right time to prune? Bonsai maintenance pruning isn't a mechanical task or a simple cosmetic trim, but a strategic decision that affects the tree's health and future branching. The first question you should ask yourself is never "how much should I remove?" but rather "does this branch still need to grow and thicken, or is it ready to be refined?"

Cutting in the wrong place or at the wrong time means wasting the energy the plant has invested in new growth. In this guide, we'll explore how to read nodes, identify buds, and choose which extensions to shorten, respecting the botanical identity of each specimen. In our workshop, our nursery staff apply these principles every day, aware that each species responds differently. Together, we'll discover how to assess vigor, distinguish a simple leaf from a compound one, and apply a rigorous observation method before making any cuts. You can find the current offerings in our online bonsai collection.

Before pruning: growth, vigor, and objectives

Bonsai maintenance pruning requires first assessing vigor: a weak branch or one in the structural development phase should not be shortened, but left to grow so it can build up energy and girth.

The success of bonsai maintenance pruning depends on the ability to distinguish the plant's development stages. Not every long branch is ready to be cut. A sacrifice branch, for example, is left to grow freely for years with the sole purpose of thickening the section of trunk beneath it or the primary branch from which it originates. If you shorten this extension, you eliminate its potential to draw sap, drastically slowing the process of structural maturation.

By contrast, refinement pruning concerns secondary and tertiary branches that have already reached the desired diameter. Here, the goal changes: we are no longer seeking volume, but density. By shortening the new shoot, we interrupt apical dominance, or the plant's tendency to concentrate energy at the very tip of the branch. This hormonal block forces dormant back buds to break, stimulating the formation of new forks and filling out the canopy harmoniously.

However, this operation requires careful assessment of the plant's overall vigor. A plant recovering from a disease, a stressful repotting, or a lack of water will not become stronger if you reduce its leaf area. Leaves are the tree's solar panels; removing them means taking away vital energy. If the specimen is not showing vigorous growth, with turgid leaves and well-spaced internodes, the best choice is always to observe and postpone the work until a more favorable season.

The decision-making process must be rigorous: intervene only if the branch has reached the correct thickness and the plant is thriving; check for stunted growth or abnormal leaves; postpone if the time of year is not compatible with the species' physiological response. There is no absolute timing rule, since the timing depends on shoot maturity and the specific climatic conditions in which the specimen is grown.

Node, bud, and direction: reading the shoot

Reading the shoot means identifying the vital node and understanding how the dormant bud's orientation will determine the direction of the new branch, avoiding random cuts that compromise the aesthetic.

To make a proper cut, you must first understand the basic anatomy of a branch. The key point is the node, the slightly swollen area of the stem from which leaves emerge and where the axillary buds are located. The space between two consecutive nodes is called an internode. When we carry out maintenance pruning, our goal is to cut the internode, leaving the node below it and its valuable bud intact.

The exact distance to cut from the node cannot be defined in universal millimeter measurements for all species. As a general guideline for most deciduous trees, leave a small amount of wood (often just a few millimeters) above the bud to allow the tissue to recede and heal without drying out the bud itself. If you cut too close, you risk compromising its vitality; if you cut too far away, you will create an unsightly stub of dead wood that could become a breeding ground for pathogens.

Where growth can continue

Botany teaches us that the new branch will grow in the direction the bud left at the tip after pruning points. This is the key to building orderly branching. If you want the canopy to spread outward, select a bud that points beyond the silhouette. If you cut above a bud that points inward, the new branch will grow across the existing structure, creating visual clutter and blocking the light.

Observing the orientation of alternate or opposite leaves helps you predict this growth. In species with opposite leaves, two new twigs often develop in a "V" shape. In species with alternate leaves, the branch will grow in a zigzag pattern. Understanding this natural geometry lets you shape the empty space, which is just as important as the filled space in bonsai, ensuring air and light reach all the inner foliage.

Compound leaf and leaflet

A common mistake when examining a shoot is confusing a simple leaf with a compound leaf. Some species develop compound leaves, made up of a central axis (rachis) along which numerous small leaflets are arranged. If you cut the rachis thinking you are shortening a branch, you are simply mutilating a single leaf. This cut will not stimulate any branching, but will only cause the severed portion to dry out.

To prune correctly, follow the petiole of the compound leaf to where it attaches to the true woody or semi-woody branch. This is where the node with the dormant bud is located. Recognizing this difference is essential to avoid stressing the plant unnecessarily and to ensure that pruning produces the desired hormonal effect: awakening dormant buds further back along the true stem.

Six bonsai, six different considerations

Each species responds differently to pruning. From preserving fruiting wood in apple trees to managing the compound leaves of pepper (Zanthoxylum piperitum), pruning must respect the tree's specific physiology.

Not all broadleaf trees can be treated with the same intensity or at the same time of year. Following a generic schedule inevitably leads to cultivation errors. We have selected six representative species, also found among the varieties grown at our nursery in Italy, to show how observation should guide your pruning shears. This comparison table will help you tailor your approach to the specimen's botanical identity.

As the table shows, caring for a Malus requires special attention to preserving short shoots, which are essential for flowering, while for Zanthoxylum piperitum, the main challenge is correctly identifying the leaf structure. There is no universal rule: knowledge of the species is the fundamental prerequisite for any maintenance work.

A considered maintenance cut

The pruning procedure requires a methodical approach: isolate the shoot, identify the cut-back point, use sharp tools, and check the result before moving on to the next branch.

Tackling the entire canopy can be confusing. The safest method is to proceed gradually, assessing one branch at a time. Always start at the top of the plant, where vigor is usually strongest due to apical dominance, then work down to the lower branches. This approach lets you balance the tree’s energy, slowing down vigorous areas and leaving untouched the weaker areas that need to develop.

Let’s take a healthy Olea europaea (olive tree) as a practical example. Look for a vigorous shoot that has grown considerably longer. As a general guideline for this species during a strong growth phase, the technique recommends letting the shoot grow to six or eight pairs of leaves, then shortening it to leave just one or two pairs of leaves at the base. This count is not a mathematical rule for every branch, but a guideline for shoots that need to be shortened to encourage back-budding and thicken the structure.

The correct pruning sequence is as follows: first, visually isolate the suitable shoot. Then identify the cut-back point, that is, the node with a bud facing the desired direction. Position the scissors at a clean angle, slightly above the bud, and make a clean cut without fraying. Finally, check the result: does the branch fit harmoniously into the silhouette? If so, move on to the next shoot. This deliberate slowness is the secret to high-quality branching.

After pruning: observe, don't add more procedures

After pruning, the plant's ability to transpire is reduced. It is vital to adjust watering and avoid adding further stress, such as repotting or excessive fertilizing.

Once maintenance pruning is complete, the bonsai enters a rebalancing phase. You have removed some of its foliage, which means the plant has temporarily lost some of its photosynthetic "engines" and, above all, reduced its ability to transpire. Under typical growing conditions, a tree with fewer leaves will use less water than before pruning. Continuing to water at the same frequency as before is a common mistake that can lead to dangerous waterlogging and root suffocation.

The substrate should be monitored more closely, allowing it to dry slightly on the surface before watering again. Don't be tempted to "help" the plant by increasing the amount of fertilizer. Fertilizer is not medicine; applying it to a plant that is reorganizing its sap flow can cause root burn. Maintain the regular feeding schedule only if the plant was already actively growing and temperatures allow it.

Finally, the golden rule of cultivation: never combine stressful procedures. If you have just carried out extensive maintenance pruning, do not repot, apply invasive wiring, or attempt total defoliation. The bonsai needs time to heal the cuts, activate dormant buds, and produce new growth. At this stage, your task is to ensure adequate light exposure and the right ambient humidity, while patiently observing nature's wonderful response.

Frequently asked questions about maintenance

Straightforward answers to the most common questions about managing shoots, from where to make the cut to protecting blooms, so you can prune confidently and precisely.

Where should you cut a bonsai shoot?

Make the cut at the internode, leaving a small safety margin (a few millimeters) above a viable node. It is essential to choose a bud pointing toward the outside of the canopy or in the direction you want the new branch to grow, avoiding inward crossings that would deprive the vegetation below of light and air.

When is it best to let a branch grow out?

A branch should be allowed to grow freely when it serves as a "sacrifice branch," meaning it helps thicken the trunk or the primary branch from which it grows. You should also avoid pruning if the plant is weak, recovering from disease, or if the branch itself has not yet reached a diameter proportionate to the rest of the structure.

How many leaves should you leave after pruning?

There is no universal fixed number. As a general guideline for vigorous shoots of many deciduous trees (such as olive trees), wait until 6-8 pairs of leaves have developed, then shorten to 1 or 2 pairs. The key is to always retain enough foliage to maintain sap flow and avoid excessively weakening the branch being pruned.

Are the leaflets of a pepper tree bonsai whole leaves?

No, Zanthoxylum piperitum (pepper tree bonsai) has compound leaves, made up of a central rachis bearing several small leaflets. Cutting between leaflets means mutilating a single leaf, not the branch. To prune correctly, identify the true woody stem and cut above the node from which the entire compound leaf grows.

How can you avoid sacrificing apple blossoms and fruit?

In the genus Malus, flowers and future fruit develop on short, stubby branches called spurs. During maintenance pruning, shorten only the long, vigorous vegetative shoots, taking great care to identify and preserve the short, mature wood, which is the plant's true aesthetic and reproductive asset.

Can all deciduous trees be pruned at the same time of year?

Absolutely not. Each species has different growth rates and shoot maturation patterns. While some oaks require targeted pruning of new spring growth, species such as Pyracantha need attention after flowering to avoid compromising the berries. Always prioritize observing the individual plant's stage of development over following general calendars.