Early spring in the vineyard may seem like a quiet time, but this season presents grape growers the unique opportunity to make major changes to their crops. Grafting is the horticultural process of combining the tissues from two separate plants so that they grow together into one.
Grapes and grafting have a long history. Grafting is a way to ensure that every plant produces the same fruit when growers want a consistent crop. Many crops are propagated through grafting, including citrus, apples, pears, maple, even rubber plants.
What’s Field Grafting?
In a vineyard, field grafting grapevines refers to changing over an established vineyard to a different grape variety. The average grapevine lifespan is 25+ years. During that time, drinking trends can change. Merlot, for example, was hugely popular through the early 2000s, but was quickly replaced by Pinot Noir and Cabernet Sauvignon. Grafting wine grape vines from Merlot to a more popular variety means that the producer can meet the market demand without having to replant the vineyard. Vines use their current root systems to support vine material from the new variety.
How Grafting Works
Vineyard grafting is a major surgical process. Growers cut off, or "head", the entire top of the vine leaving the trunk. They take two small cuttings, called scions, from the vines of the variety they want to grow. These scions have two buds that will grow into a new canopy, or leaves, in the coming season. At this point, the grower has three options for grafting: cleft grafting, t-budding, or chip budding. For each of these methods, the grower makes incisions in the trunk head and carefully matches up the tissue layers of both the scion and the trunk so that they heal together.
Cutting into the vine makes it susceptible to infection. The wound area gets covered in a black grafting compound. Once it dries, the area is painted over with a white latex paint for further protection.
Grafting wine vines isn’t a guaranteed success. The first signs that the graft union worked comes the following summer when the new buds push out leaves. It will still take another 3 years before the newly grafted vineyard produces a crop.
You can tell if a vineyard has been field grafted by looking at the top of the vine where the arms, or cordons, grow out of the trunk. The vine will have what looks like a horizontal ring running around the head of the vine right at that juncture.
Vines can be grafted over multiple times during their lifespan, repeatedly reinventing themselves. The next time you find yourself driving through vineyards, pull over and take a look at a grapevine. See if it has a story to tell!
Author Bio: Erin O’Reilly is a Certified Specialist of Wine with the Society of Wine Educators and a long-time lover of all things fermented grape. She pens her work from Monterey wine country where she raises a glass to the growers and producers crafting wines that transcend time.