Green Harvest

Why green harvest is done

A grapevine can only ripen so many bunches to the desired sugar and flavour level. If the crop is too large, the vine struggles, the grapes ripen unevenly and the resulting wine is thin and green. Green harvest is the cure: by removing 20 to 40 percent of the bunches in July or early August, the winemaker lets the vine focus its energy on the remaining fruit, which then ripens faster and more completely.

The trade-off is volume. A green-harvested vineyard produces fewer bottles per hectare, which means higher costs per bottle. But the wines are riper, more concentrated and more ageworthy, which is why premium producers consider the practice essential.

When to green harvest

The timing matters. Green harvest is usually done after fruit set and before véraison, the period when the berries change colour and start to soften. Cutting later than that gives little benefit, because the vine has already invested too much energy in the unwanted bunches. Cutting too early can lead to over-cropping the following year, because the vine compensates with more buds the next spring.

Most UK growers green harvest by hand, walking the rows with secateurs and dropping the unwanted bunches to the ground. The cost is significant, often 200 to 400 pounds per hectare, but the result is a tangible lift in fruit quality.

Yield and the PDO rules

The English PDOs set maximum permitted yields per hectare, and green harvest is the main tool for staying within them. The English Sparkling PDO cap is around 12 to 14 tonnes per hectare, depending on the category, and a typical sparkling wine vineyard in the UK will green harvest to 8 to 10 tonnes. The still wine PDOs are similar, though with more flexibility for table wine categories.

A pre-harvest estimate is done in late summer, with the winemaker walking the rows and weighing sample bunches. If the projected yield is above the cap, more green harvest is done. If it is below, the winemaker may choose to leave the extra bunches on, depending on the vine's condition and the season's prospects.

What the bunches are used for

The dropped bunches are usually left on the ground to compost back into the soil. Some producers collect them and send them for distillation, but this is rare in the UK. A few innovative producers have used green-harvested bunches to make a verjus, the tart juice of unripe grapes used in cooking. Hambledon and Davenport have both experimented with English verjus as a by-product.

From a sustainability angle, green harvest is sometimes criticised as wasteful. The argument is that the vines were never going to ripen that many bunches anyway, and the energy could have been conserved. The counterargument is that without the crop thinning, the wine would be undrinkable, and the energy was going to be wasted either way.