Introduction to Bonsai Grafting: Types, Timing & Step-by-Step Technique Guide

# Grafting (Grafting): A Complete Guide to Improving Bonsai

Grafting (接ぎ木) is a propagation and improvement technique that combines the characteristics of different plants by attaching one plant (scion) to the roots of another plant (rootstock). In the bonsai world, grafting is far more than just a means of reproduction—it's utilized for multiple purposes including filling in missing branches, developing rare varieties, and strengthening tree vigor through the use of specific rootstocks.

Grafting may seem difficult, but once you understand the basic principles and procedures, you'll find that success rates are surprisingly high when done at the right time and in the correct manner.

Purposes of Grafting in Bonsai

The main purposes of grafting in bonsai are as follows:

1. Propagating Rare Varieties Rare varieties that are difficult to propagate through cuttings or seeds can be reliably developed using grafting, leveraging the root strength of the rootstock.

2. Filling In Missing Branches (Branch Grafting) When a long-established bonsai lacks branches in the ideal position, grafting a scion of the same species can complement the tree's form.

3. Utilizing Rootstock Root Power By grafting a rare variety onto a vigorous rootstock (for example, applying an apple variety to a hawthorn rootstock), even weak species can grow vigorously.

4. Early Flowering and Fruit Production Grafting often produces earlier flowering and fruit production compared to plants grown from seed. This effect is particularly noticeable in plum and wisteria.

Types of Grafting

Cleft Grafting (Splice Grafting)

The trunk or branch of the rootstock is cut, and the scion is inserted into the cut surface. This is the most commonly used basic grafting method.

• Best Time: Just before spring budbreak (February–March)
• Characteristics: High reliability; relatively easy even when trunk diameters don't match perfectly

Bud Grafting

A T-shaped cut is made in the rootstock's bark, and the bud of the scion (bud shield) is inserted into it.

• Best Time: Summer (July–August), when bark easily separates
• Characteristics: Uses minimal scion material; high success rate when done correctly

Side Grafting

A method in which the trunk or branch is not cut; instead, a lateral cut is made and the scion is grafted into it. Ideal for filling in missing branches.

• Best Time: Around spring budbreak
• Characteristics: Causes minimal damage to the rootstock; optimal for filling in missing branches

Root Grafting

A specialized method in which the scion is grafted onto roots or the root collar area. Used for adding or reinforcing large roots.

Necessary Tools

• Grafting Knife: Use one with the sharpest blade possible
• Rubbing Alcohol for Sterilization: Sterilize the blade before and after use
• Grafting Tape (Vinyl Tape or Raffia): For securing the scion and rootstock
• Healing Compound (Cambium Dressing): To prevent desiccation and infection of cut surfaces
• Vinyl Bag or Damp Cloth: For storing the scion

Practical Procedure for Cleft Grafting

The procedure for cleft grafting, the most commonly used method, is explained below.

Preparation

Collecting the Scion: Collect the branch that will serve as the scion 1–2 weeks before grafting and store it in a refrigerator (32–41°F / 0–5°C) to prevent desiccation. Alternatively, collect and use it the same day. Select a healthy branch with 3–5 nodes.

Selecting the Rootstock: Choose a healthy rootstock with strong vigor that is the same species or a closely related species as the scion. The closer the rootstock's trunk diameter is to the scion, the easier it will be to align the grafting surfaces.

Grafting Procedure

1. Cut the Rootstock: Cut the rootstock in one clean motion with a clean knife at the grafting location. The cut surface should be horizontal or slightly angled.

1. Make a Cut in the Rootstock: Make a vertical cut (wedge-shaped) about 2–3 cm deep in the center or slightly inside the cut surface.

1. Shave the Lower Part of the Scion: Shave the lower end of the scion at a length of 2–3 cm symmetrically (or on one side) at an angle, creating a wedge shape. Make the shaved surface as long and smooth as possible.

1. Insert the Scion into the Rootstock: Insert the wedge-shaped portion of the scion into the cut in the rootstock. It is crucial that the cambium layer (thin green layer) aligns between the rootstock and scion. If the cambium layers don't align, the graft won't take.

1. Secure with Tape: Wrap grafting tape around the graft from bottom to top to ensure the scion remains firmly in place.

1. Apply Healing Compound: Apply healing compound to the upper cut surface of the scion to prevent desiccation.

1. Aftercare: Keep the graft away from direct sunlight and desiccation, placing it in a bright shaded location. Loosely placing a vinyl bag over it to maintain high humidity is also effective.

Confirming the Graft Take

If the scion's buds begin to swell 2–4 weeks after grafting, the graft has likely taken successfully. Leave the tape in place for several months, then remove it once the grafting site has stabilized.

Common Failures and Solutions

Misaligned Cambium Layers: The most common cause of failure. Match the sizes of the scion and rootstock carefully, ensuring that at least one side's cambium layer is perfectly aligned.

Failure Due to Desiccation: If the cut surface dries out, the graft won't take. Work as quickly as possible, protecting cuts with tape and healing compound.

Infection: Contaminated tools can introduce infection leading to death. Thoroughly sterilize the blade with alcohol every time.

Summary

Grafting is an advanced bonsai technique, but if you carefully follow the fundamentals, even beginners can experience the joy of success. Start with spring cleft grafting and, building on your successes, explore other grafting techniques.