Pruning

Why pruning matters

A grapevine left to its own devices will grow vigorously, producing a mass of tangled canes and a small crop of poor-quality grapes. Pruning tames the vine, restricting the number of buds so that the remaining shoots can ripen the fruit, and shaping the vine so that the canopy is manageable and the fruit is accessible.

The wrong pruning decision is one of the most expensive mistakes a vineyard can make. Too few buds, and the vine over-crops, producing big yields of poor-quality fruit. Too many buds, and the vine under-crops, producing small yields of vigorous, leafy growth. The right balance depends on the variety, the site and the winemaker's intent.

Pruning systems used in the UK

The most common UK pruning system is the double Guyot, used for Vitis vinifera varieties on the typical vertical shoot positioning trellis. Two canes are laid down horizontally on a low wire, each carrying 6 to 10 buds, and a short spur is left for renewal. This is the standard Champagne and Burgundy system, and it works well in the UK.

For Seyval Blanc and other hybrids, a single Guyot or a more elaborate Scott Henry system is sometimes used. For the most vigorous sites, a VSP with a tighter pruning may be needed. The choice of system is set at planting, but it can be changed later if the vine's behaviour suggests a different approach.

When to prune in the UK

UK pruning usually starts after leaf fall, often in late November or December, and continues through to bud break in April. The earliest and latest dates carry some risk. Pruning too early can stimulate the vine to push buds during a warm spell in winter, only for them to be killed by a later frost. Pruning too late can delay bud break, which is sometimes useful on frost-prone sites.

Many UK growers split pruning into two passes. The first pass, in late autumn or early winter, removes the bulk of the wood and leaves long canes. The second pass, in late February or March, cuts the canes back to their final length. This two-pass system is labour-intensive but gives the most precise control.

Mechanisation and the future

Pruning is the most labour-intensive vineyard operation, accounting for a significant share of UK vineyard costs. Manual pruning on a hectare of vines takes around 80 to 120 person-hours. Mechanical pruning, using tractor-mounted cutter bars, can do the same job in 2 to 4 hours, but it is less precise and can lead to over-cropping.

The most exciting development is robotic pruning, which is being trialled at Plumpton College and a handful of forward-thinking UK estates. Robots can identify and cut individual canes using cameras and AI, giving the precision of hand pruning with the speed of a machine. The technology is still young, but the early results are promising.