How to Graft Plants: A Practical Introduction

Grafting joins the shoot of one plant — the scion — onto the root system of another — the rootstock — to combine the fruiting qualities or ornamental character of the scion with the root vigour, disease resistance, or size-controlling properties of the rootstock. It is the standard method of producing fruit trees and roses commercially, but it is entirely achievable at home with sharp tools, the right timing, and an understanding of why cambium alignment is everything.

Why Cambium Alignment Is Everything

The cambium is the thin green layer of actively dividing cells that lies just beneath the bark. A graft succeeds only if the cambium of the scion and the cambium of the rootstock are pressed tightly together — the two layers fuse and form a callus that eventually becomes permanent vascular tissue. If the cuts are even slightly misaligned or if air dries out the exposed tissue before they are bound, the graft fails. Speed, sharp blades, and immediate binding are the three pillars of successful grafting.

Whip-and-Tongue Grafting

This is the most commonly used bench-grafting technique for fruit trees. Both scion and rootstock should be pencil-thickness and as nearly equal in diameter as possible. Cut both at a long 45-degree slant, then cut a short tongue into the slanting face of each — a notch that interdigitates and prevents the graft from sliding apart. Push the two pieces together, matching the cambium on at least one side, and bind tightly with grafting tape or strips of polythene. The tape holds moisture in and pressure on the join while callus forms.

Cleft Grafting for Larger Stems

When the rootstock is much thicker than the scion — for top-working an existing tree, for example — cleft grafting is more practical. Saw off the rootstock cleanly and use a grafting knife to split it vertically 3–4 cm deep. Cut two scions with a long, smooth wedge at their base and insert one at each side of the split, ensuring the cambium of each scion aligns with the cambium of the rootstock. Bind and seal all cut surfaces with grafting wax or sealant to prevent drying. Remove the weaker scion after the stronger one takes.

Aftercare and Union Development

Keep grafted plants in a humid, sheltered environment while the union forms — a cold frame or glasshouse is ideal. New growth from the scion signals a successful take, usually within three to six weeks. At this point, gradually ventilate and harden off. Remove any shoots arising below the graft union from the rootstock promptly — these are vigorous and will outcompete the scion if left. Check the binding tape after six weeks; if the union has formed well, the tape can be loosened before it constricts growth.