Bonsai Grafting Guide | Complete Guide to Types, Timing, and Procedures
A detailed explanation of grafting types used in bonsai such as splice grafting, bud grafting, and root grafting, along with their purposes, appropriate timing, and practical procedures. We also introduce techniques for grafting rare varieties onto rootstocks and branch grafting to supplement missing branches.
Key Takeaways
A detailed explanation of grafting types used in bonsai such as splice grafting, bud grafting, and root grafting, along with their purposes, appropriate timing, and practical procedures. We also introduce techniques for grafting rare varieties onto rootstocks and branch grafting to supplement missing branches.
Grafting is a propagation and improvement technique that combines the characteristics of different individual plants by joining a scion (upper part) of one plant to the root of another plant (rootstock). In the world of bonsai, grafting is not merely a means of propagation, but is utilized for multiple purposes such as supplementing missing branches, training rare varieties, and strengthening tree vigor through the use of specific rootstocks.
Although grafting may seem difficult, if you understand the basic principles and procedures and perform it at the appropriate time correctly, the success rate is surprisingly high. As of 2026, many bonsai enthusiasts perform grafting themselves to increase rare varieties.
Purposes of Grafting
The main purposes of grafting in bonsai are as follows.
1. Propagation of Rare Varieties Rare varieties that are difficult to propagate by cutting or seed can achieve stable growth through grafting by utilizing the vigor of the rootstock. For example, dwarf varieties with weak tree vigor or varieties that are difficult to flower fall into this category.
2. Strengthening Tree Vigor Weakened plants or trees with declining vigor can sometimes be revived by grafting onto a vigorous rootstock.
3. Supplementing Missing Branches When an important branch is lost due to typhoon damage or winter breakage, grafting a scion of the same species can restore the tree closer to its original form.
4. Customizing Tree Form For example, you can achieve a "landscape design" style of training where an older tree with a thick trunk is grafted with scions from a young tree to combine age and vigor.
Timing of Grafting
Pine: Mid-April to early May (when new buds begin to emerge) Deciduous trees: Late March to early April (when activity begins) Flowering trees (plum and cherry): Late February to early March
The key to selecting the season is to aim for a time when both the rootstock and scion begin activity and the cambium layer is actively moving.
Methods of Grafting
Splice Grafting (Most Common)
- Scion Preparation: Cut a 10-15 cm scion with closely-spaced nodes from the new growth of the previous year.
- Scion Cut: Cut into a wedge shape, with the lower part made with two faces.
- Rootstock Preparation: Cut horizontally at a position where the thickness is similar to the scion.
- Joining: Insert the wedge-shaped scion into the split in the rootstock, ensuring the cambium layers overlap completely.
- Securing: Secure firmly with plastic twine or tape.
The key to success is that the cambium layers come into close contact with each other.
Bud Grafting (For Midsummer)
This method is performed in summer, where a single bud is taken from the scion and inserted into the debarked area of the rootstock. While this method has a more limited timing than splice grafting in spring, if successful, new growth will emerge the following spring.
Management After Grafting
Immediately After Grafting:
- Place in a shaded, humid environment, avoiding direct sunlight
- Do not loosen the securing material until new growth has extended about 5 cm
- Water thoroughly every day
During Callus Formation (2-3 weeks later):
- Gradually increase the time exposed to sunlight
- Slightly loosen the securing material
After New Growth Appears:
- Cut back the upper part of the rootstock to concentrate nutrients on new growth from the scion
- Vigorously growing new shoots should be pinched back moderately to increase the number of branches
Species-Specific Considerations
Pine: The cambium layer's activity is vigorous only for a short period. A helpful strategy is to adjust the timing slightly and attempt grafting multiple times to increase the success rate.
Deciduous Trees: Both splice grafting and bud grafting are possible. It is important to select a rootstock that is compatible with each species.
Flowering Trees: Compatibility varies by species. For example, plum grafts best onto plum, and cherry onto cherry.
Common Failures
Failure 1: The Graft Does Not Take
- Cause: Insufficient contact between cambium layers or incorrect season
- Solution: Try again in the next season
Failure 2: The Graft Takes But Tree Vigor Is Weak
- Cause: The rootstock has weak vigor or the scion is of poor quality
- Solution: Develop a vigorous rootstock before grafting the scion
Failure 3: New Growth Appears But Breaks at the Base
- Cause: The graft union is moving due to the weight of new growth, or the joining surface is incomplete
- Solution: Support the graft union with a stake while new growth is extending to minimize movement
Advanced Technique: Multiple Grafting
"Multiple grafting," where several varieties are grafted onto a single rootstock, is also an advanced bonsai technique. By combining varieties that flower at different times, you can enjoy extended flowering periods.
Conclusion
Grafting is one of the most widely used techniques in the history of bonsai. The process of mastering the fundamentals and finding the method best suited to your own trees allows you to appreciate the profound depth of bonsai.