Grafting is a good way to propagate Japanese maples. If you are new to grafting, you may want to graft several scions to several rootstock to increase your chances of success. A scion is the branch cut from an existing maple that is attached to a new rootstock.
One advantage of grafting over growing from seed is that you will know the exact characteristics of the final tree. Grafting will create a tree that is genetically identical to the one from which you removed the scion.
Cut the scions when the tree is dormant. The best scions are ones cut in the winter, but you may have good results from scions cut in the summer after the tree has finished growing and shows no new buds. A rule of thumb for cutting scions is to cut them from late July to early March.
Select a healthy Japanese maple for the root stock. The root stock should have a trunk at least the thickness of a pencil. Try to match the thickness of the trunk of the rootstock to the thickness of the scion.
Graft your scion to your rootstock in winter when the scion is dormant, but the rootstock is actively growing. The best way to ensure that the rootstock is actively growing is to graft to a rootstock that is growing indoors in a pot.
The best way to ensure a healthy rootstock is to allow the rootstock to go dormant by leaving it outside in the cold for around six weeks. Bring the rootstock inside for a week or so to allow the roots to begin growing again.
With a grafting knife, make a sloping downward cut in the bark of the rootstock about one inch long. Be sure some wood is attached to the bark. The cut should be at around a 15-degree angle and some wood should be attached to the bark near the bottom of the cut.
Make straight cut at the base of the flap to remove the flap from the rootstock.
Cut the base of the scion at an angle that matches the notch in the rootstock.
Place the scion on the rootstock. Make sure the cambium, or the new wood growth area, of the rootstock and the scion come into contact with each other.
Secure the grafted scion with grafting tape, grafting wire, or a rubber grafting strip.
Seal the graft with grafting wax or grafting paint. This will help prevent the graft from drying out.
Cut off any growth above the graft and prune off any branches below the graft.