Grafting is the cultivation practice of surgically combining the root system of one plant with the branch of another to create a better overall plant known as a hybrid. Chestnuts are a unique variety of nut tree, in that their trunks are grafted onto a nut after it begins germinating. When grafting plants, razor-sharp sanitized tools are vital for success, as these tools prevent diseases and damage in the grafted plants.
Obtain freshly fallen chestnuts from the ground and place them in a plastic zipper bag with moist peat moss. Store them in the refigorator for 3 months to encourage germination.
Once roots form, gather budwood from the desired variety of chestnut tree. Budwood is simply a piece of a small branch, less than 1 inch in diameter and 2 inches long. The budwood should be from a tree that is less than 5 years old, healthy and a good producer. Check that the budwood has at least one leaf bud; ideally, it should contain two or three.
Clean and sanitize the grafting knife with an alcohol pad and cut the bottom end of the budwood so that its end forms a pie-shaped point roughly 1/2 inch in length.
Resanitize the knife and cut an incision into the top of a chestnut that is roughly the length of the cut end of the budwood.
Slowly and gently push the budwood into the chestnut until the entire point is inside the nut.
Wrap the grafted area with grafting tape to hold it in place and lock in moisture. Then wrap the entire tree in a plastic sandwich bag with holes poked in it for aeration.
Place the grafted nuts in a heated glass frame with 5 parts moist peat moss to 2 parts vermiculite to encourage rooting. Keep the graft at a consistent 75 degrees F for 5 to 6 weeks.
Once firm roots are growing from the nuts, remove them from the frame, unwrap the plastic and transplant them into small planting pots with potting soil.
Care for the plants in a warm, well-lit area until leaves form on the graft, then transplant the trees outdoors. Water the new trees twice a week for the first 2 months, at which time the new tree should be established. After that, water the plant whenever the ground is dry at 2 inches from the surface.