Grafting is a horticultural technique where tissues from one plant are inserted into those of another so that the two sets of vascular tissues may join together. In simple terms, it is the art of physically connecting a piece of one plant (called the scion) to the root system of another (called the rootstock) to create a single, composite plant that grows as one.
The primary purpose of grafting is to combine the best qualities of both plants. The scion is chosen for its desirable fruits, flowers, or growth habit, while the rootstock is selected for its traits like disease resistance, cold hardiness, or adaptability to specific soil conditions. This allows gardeners and farmers to propagate plants that cannot be easily grown from seed and to ensure the consistent quality of the harvested fruit.
For grafting to be successful, one vital rule must be followed: the cambium layers of the scion and rootstock must be aligned. The cambium is a thin layer of actively growing cells located just beneath the bark. When these layers are placed in contact, they multiply and fuse, forming a functional vascular bridge that allows water and nutrients to flow from the rootstock to the scion.
There are numerous grafting techniques, each suited to different plants and situations. Common methods include whip and tongue grafting for similar-diameter stems, cleft grafting for adding varieties to established trees, and bud grafting, which uses only a single bud. The chosen method depends on the plant type, the size of the rootstock and scion, and the time of year.
Grafting Techniques
Whip and Tongue Grafting
This is a highly precise technique ideal for connecting scion and rootstock of similar diameter (typically pencil-thick). Both pieces are cut with a long, sloping “whip” cut. Then, a thin, downward “tongue” is cut on the rootstock and an upward tongue on the scion, allowing them to interlock firmly. This creates a strong union with extensive cambium contact for successful healing, making it popular for fruit trees and ornamentals.
Cleft Grafting
Used for top-working established trees or adding new varieties to a rootstock larger than the scion. The rootstock branch is cut squarely and split open with a grafting tool. The ends of two or more slender scions are whittled into a long, thin wedge. These scions are then inserted into the cleft on the outer edges, aligning the cambium layers. The entire union is sealed with grafting wax to prevent drying.
Side-Veneer Grafting
This technique is common for conifers and is performed while the rootstock is actively growing. A long, shallow downward cut is made into the side of the rootstock, but not through it, creating a flap. The base of the scion is cut with a long, matching sloping cut. The scion is slid into the flap on the rootstock so that the cambium layers meet, and the union is then wrapped and sealed.
Bud Grafting (Budding)
Budding uses a single bud instead of a scion with multiple buds. The most common form is T-budding. A ‘T’-shaped cut is made in the rootstock’s bark. A bud shield (a piece of bark with a bud attached) is carefully sliced from the scion wood and slipped underneath the flaps of the ‘T’ cut. It is then wrapped tightly, leaving the bud exposed. This is efficient and uses minimal scion material.
Bridge Grafting
This is a repair technique used to save a tree with girdled or damaged bark around its trunk. Scions of a compatible variety are cut to a length that bridges the damaged area. Both ends of each scion are cut with a wedge. These ends are inserted under the healthy bark above and below the wound, creating a “bridge” for sap to flow across. The scions are nailed in place and sealed.
Bark Grafting
Similar to cleft grafting, bark grafting is used for large-diameter rootstocks. Instead of splitting the wood, the bark is carefully cut and peeled away from the stump. Several scions, cut with a long tapering cut on one side, are inserted between the bark and the wood. Pressure is applied by nailing or tying, and the entire area is sealed. This is less stressful for the tree than cleft grafting.
Splice Grafting
This is one of the simplest grafting methods. Both the scion and rootstock of the same diameter are cut on a long, matching diagonal. The two cut surfaces are placed together and wrapped securely. While simple, it lacks the mechanical interlocking of a whip and tongue graft, making the union weaker until fully callused. It is often used for plants that callus easily, like grapes.
Saddle Grafting
In this technique, the rootstock is cut to form a point or an inverted ‘V’ (the saddle). The base of the scion is cut with a matching notch (the saddle) so that it sits perfectly on top of the rootstock. This method provides excellent cambium contact on both sides of the stock and is a very strong union, suitable for plants like rhododendrons and clematis.
Approach Grafting (Inarching)
In approach grafting, two plants are grafted while still growing on their own roots. A slice of bark and a thin layer of wood are removed from similar-sized stems on both plants. The two wounded areas are bound tightly together. Once the union has healed, the top of the rootstock plant is removed above the graft, and the bottom of the scion plant is removed below the graft.
Four-Flap Grafting (Banana Graft)
Known for its high success rate, this method involves making four precise vertical cuts on the rootstock and peeling the bark down like banana peels to create flaps. The scion is prepared with matching long, tapering cuts. The scion is inserted into the rootstock, and the flaps are folded back up and wrapped. It provides extensive cambium contact but requires more skill.
Softwood Grafting
This technique is performed on young, succulent (softwood) shoots that are still green and flexible. A wedge or whip and tongue graft is made, but because the tissues are tender, they callus and unite very quickly. It is often used for plants that are difficult to propagate from hardwood cuttings and must be done under high-humidity conditions to prevent the scion from wilting.
Stub Grafting
A space-saving technique often used in fruit tree nurseries. Instead of grafting at the base of the rootstock, a small scion is grafted onto the side of an established rootstock or branch. The tip of the rootstock is removed only after the scion has successfully taken. This allows the rootstock to continue sustaining the scion during the healing process and is useful for introducing a new branch into a bare area of a tree.