Growing methods

Approach grafting and thread grafting

When we want our bonsai to grow as optimally as possible, we use techniques such as lapping and drill grafting. These methods can be used to compensate for undesirable natural developments such as an inharmonious root base or missing trunk branches.

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The shoot threaded through the Japanese maple is visibly thicker on the left than on the right of the trunk. — Growing methodsPractical article / Bonsai Kreativ

Instructions

These techniques can be used for almost all types of trees. Such interventions are particularly easy to carry out on thin-barked trees such as maple, beech, ash, apple or sycamore. Trees such as Prunus or Periwinkle, which have a thicker bark, also work with these techniques, the results just take longer. While the results of thin-barked trees can be seen after a few months, evergreens need several years. For these techniques, people like to use their own branches or seedlings.

When should the different techniques be used?
Spring is a good time to lactate the roots. The ideal time is when the worst of the cold has passed and the trees are not yet sprouting. Basically, the branches can be left throughout the year. However, the ideal time is before bud break. For deciduous trees, the beginning of June is a good time and laxation should take place after the first leaf cut.

A time when the tree has no leaves is always ideal for grafting. This can be the case in March or in June after the first leaf pruning. The following applies to all techniques: they should not be used in winter, as frost damages fresh and open wounds.

Example of root grafting on a plane tree in March

Our plane tree has already formed a very nice nebari, but an unsightly gap has formed between two thick roots. We are now filling this gap with a one-year-old sycamore seedling.

Step 1

First, we make an incision between the two thick roots, the later "cutting point". We have to cut through the cambium.

Figure 01/18– A knife lifts a narrow strip of bark between two thick roots of the plane tree.

Figure 02/18– The elongated cut surface between the plane tree's roots is exposed, with a green edge beneath the bark.

Step 2

We also cut the seedling at a suitable point, the cambium must be exposed here. This allows the cambium to reach the cambium when the seedling is connected.

Figure 03/18– A plane tree seedling rests on a hand, with bark removed from an elongated patch.

Step 3

We attached the seedling to the sycamore in the correct position with nails. Now only the upper branch of the seedling needs to grow. The lower part forms a new root and thickens. The procedure causes callus to form and the seedling becomes a sacrificial branch.

Figure 04/18– The seedling secured at the plane tree's root base extends diagonally upwards in front of the trunk.

Figure 05/18– Red and green drawing pins secure the seedling in the prepared site between the plane tree's roots.

Step 4

It finally took two years for the new root to grow in completely and become sufficiently thick.

Figure 06/18– A black arrow marks the thickened base of the approach-grafted seedling at the foot of the plane tree.

Step 5

Here once again the new ingrown root. We have already cut off the sacrificial branch at this point.

Figure 07/18– A finger points to the cut surface of the removed sacrifice branch between the plane tree's roots.

Example of laxation on a stone cherry (Prunus mahaleb)

We carried out the procedure in June after the first leaf pruning. The trunk of our tree had not formed a lateral branch over a large area, so we left a new branch here. We used one of its own lateral branches for this purpose. The process until complete intergrowth can take around two to three years for this tree

Result

Here you can see the successfully ingrown shoot.

Figure 08/18– A knife blade rests beside a freshly exposed elongated patch in the mahaleb cherry's bark.

Figure 09/18– A green shoot lies across the prepared opening in the mahaleb cherry's bark.

Figure 10/18– Approach grafting and thread grafting techniques on a bonsai.

Example of a drill graft

For our grafting in June, we used a Japanese maple (Acer palmatum Arakawa). The Japanese maple only forms a few lateral branches on its own, so a little help is needed to achieve an attractive overall appearance. For our procedure, we used the tree's own branches, which we left to grow for a year.

Step 1

The technique starts with drilling. We drill through the branch with a thickness of around four to five millimetres.

Figure 11/18– A drill bit passes through the Japanese maple's rough-barked trunk and protrudes on both sides.

Step 2

Now simply insert the young twig through the hole and cover the open areas of the drilled hole.

Figure 12/18– The tip of a green shoot emerges from the drilled hole in the Japanese maple's trunk.

Figure 13/18– A green shoot is threaded through the Japanese maple's trunk and is visible on both sides.

Figure 14/18– Grey wound sealant surrounds the green shoot at the drilled hole in the Japanese maple.

Step 3

This result is shown after two years. If the "outgrowing" branch is significantly more pronounced than the "ingrowing" branch, this is a sure sign that the branch has grown in safely.

Drill grafting on a field maple (Acer campestre)

We used a seedling for this drill graft as the tree's own branches were not long enough for our technique.

Figure 16/18– Close-up of a slender side shoot where it joins the field maple's trunk.

Figure 17/18– A field maple with fine branching and a long shoot extending to the right; a black nursery pot stands beside it.

Result

Here you can see the successfully ingrown shoot.

Figure 18/18– A finger points to the thickened junction between the side branch and the field maple's trunk.