Grafting is a horticultural technique that joins two different plant parts so they grow together as one. This method is used to propagate fruit trees, ensuring the new tree is a genetic clone of the desired fruiting parent. Since planting seeds rarely yields the same fruit characteristics due to cross-pollination, grafting maintains specific varieties like ‘Honeycrisp’ apple or ‘Fuyu’ persimmon. The technique also allows growers to select a root system that controls the mature size of the tree, offers disease resistance, or improves tolerance to various soil types. Grafting enables fruit production much faster than trees grown from seed.
Essential Components and Timing
A successful graft relies on the fusion of two parts: the scion and the rootstock. The scion is budwood taken from the desired fruit variety, which becomes the new trunk and canopy. The rootstock is the lower portion, providing the roots and dictating characteristics like tree size, vigor, and hardiness. For the two parts to unite, their respective cambium layers must be aligned precisely, as this thin tissue layer is responsible for all new growth and wound healing.
The cambium is located just beneath the bark, and its successful connection is the most important factor for a viable graft. Grafting is best performed during late winter or early spring when both the rootstock and the scion are deeply dormant. This timing is important because the rootstock is ready to begin active growth, but the scion remains dormant, preventing it from drying out before the vascular systems connect. The ideal window is just before the rootstock’s buds begin to swell.
Preparing the Grafting Materials
Preparation starts with scion wood, typically collected while the parent tree is dormant in mid-to-late winter. Scions should be straight, healthy pieces of the previous season’s growth, about the thickness of a pencil, and possess two to three buds. After cutting, the scion wood must be stored to prevent drying, usually in a sealed plastic bag with a damp medium like paper towels or sphagnum moss. This bundle is then kept refrigerated near 32 to 40 degrees Fahrenheit until grafting day.
Preparing the rootstock involves selecting a suitable grafting point, often a limb or the main trunk, and cleaning the area. Necessary tools include a sharp grafting knife for precise cuts and a pair of bypass pruners. You will also need specialized grafting tape or rubber bands to hold the pieces together and a sealing compound or wax to cover all exposed wood surfaces. Sharp tools ensure the cuts are clean and quick, minimizing damage to the delicate cambium layer.
Step-by-Step Cleft Grafting Technique
Cleft grafting is an excellent technique for beginners, especially when joining a small scion onto a larger-diameter rootstock or branch. The process begins by making a clean, straight cut across the rootstock branch or trunk at the desired height. Next, a grafting knife is used to make a vertical split, or cleft, running downward through the center of the cut surface. This cleft should be deep enough to hold the wedge-shaped scions securely.
The scion wood is prepared by creating a long, smooth, wedge-shaped cut at the base. This wedge must have two opposing tapered sides, each about 1.5 inches long, made with a single, quick stroke to maintain a clean surface. The scion should be five to six inches long and contain two or three buds, ensuring the lowest bud is near the top of the wedge. It is beneficial to prepare two scions for a single cleft to increase the chances of a successful union.
The prepared scions are gently inserted into the cleft, one on each side of the vertical split. The goal is to align the outer edge of the scion’s cambium layer with the outer edge of the rootstock’s cambium layer. Since the rootstock is often thicker than the scion, alignment may require placing the scion slightly inward from the rootstock’s edge. A proper fit is achieved when the cambium layers touch along a significant portion of their length, maximizing the surface area for callousing.
Once the scions are correctly positioned, the entire graft union must be secured firmly to maintain cambium contact. Grafting tape or strong rubber bands are wrapped tightly around the rootstock to hold the split closed and press the scions against the inner walls. The final step is to cover all exposed cut surfaces—the top of the rootstock, the entire cleft, and the top-cut surface of the scions—with grafting wax or compound. This sealing prevents moisture loss and protects the tissue from pathogens and air, aiding the healing process.
Post-Grafting Care and Monitoring
After the graft is secured and sealed, proper protection encourages a strong union. The sealing wax acts as a protective barrier, preventing the scion from drying out before the vascular systems reconnect. The tight wrapping ensures the scion and rootstock remain immobile, allowing callus tissue to form without disruption. Callus formation is the initial phase of healing, where cells begin to bridge the gap between the two plants.
Monitoring the graft over the following weeks is important to gauge success. A positive sign is the swelling and breaking of the scion’s buds, which typically occurs within a month. If the scion shrivels or turns brown without bud break, the graft has usually failed due to poor cambium alignment or drying out. Once the graft union is strong and new shoots are growing, any competing growth from the rootstock below should be removed promptly to direct all energy toward the new variety.