🌿 Grafting

Grafting is the process of joining two plants so that they grow together as one. In viticulture it lets growers use the root system of one kind of grape, the rootstock, together with the shoot system of another, the scion. The rootstock gives the roots, the scion gives the wanted variety, and together they form one vine.

Why is it needed? In the late 19th century the soil-borne aphid phylloxera, which reached France in 1868, destroyed European vines. The answer was to graft European vines onto American rootstocks, which resist the pest. Today more than four-fifths of the world's vineyards use grafted plants. Rootstocks are also chosen for adaptation to soil, resistance to pests and diseases, control of vigour and drought tolerance.

How is it done? Most grapevines are bench grafted indoors using dormant wood. The scion and rootstock canes are cut and spliced so that the vascular cambium of both is at least partly aligned, often with an omega cut. The two parts then connect through callus formation at the graft union, and the young vine is callused and rooted like a hardwood cutting. The graft union must not be disturbed for a few months, and the scion may be coated with wax to protect the graft and buds.

Grafting can also be done in the vineyard or nursery. An existing vine can be changed to a new variety by budding or by cleft or wedge grafting; the cleft and wedge methods are done in spring on dormant scion canes.