• lynne coyle

Equinox, Bud Break & Frost

Updated: Aug 27, 2019

In the northern hemisphere the spring equinox on the 20th March marks the official start of our astronomical spring. This sets in motion bud break in our wine growing regions, longer days, rising temperatures and awakening vines are the order of the day.

Carneros, Napa, US - 2017

You might imagine, that after the grapes are harvested in the autumn, wine farmers spend the winter months lazing on the sofa watching Netflix. But, relaxing and forgetting about their vineyards until the spring is not an option as there are a series of jobs the grape grower sets in motion once their wine fermentations are safely underway.

As with any keen gardener, starting in the autumn, the end of season weeding and fertilising gets tackled along with a general vineyard tidy. This tidying is important to avoid undesirable fungal spores and pests or diseases overwintering in vineyard detritus.

Then, after the vines change colour and the leafs fall to the vineyard floor, the vine can enjoy a period of dormancy over the winter months. Pruning begins in earnest in January and February with as much as 90% of the old wood being removed ready for spring.

The March equinox marks the beginning of spring. The vines tiny brown buds slowly start to open on the bare wooden canes, unfurling tiny fuzzy leafs, an impossibly beautiful shade of green and delicate beyond imagination.This phase of grape growing is only the start of the years hoping, praying and worrying for the grape farmers in the grape growing season ahead.

Entering April and the buds open more fully - the biggest concern is frost. Potentially devastating after bud break, these weather events often occur in a limited way every year, but they have, in the recent past, had fatal consequences for many Northern Hemisphere wine regions.

In late April 2016 and 2017 plus in May 2017 severe frost hit vineyards in Europe with some estates reporting losses between 50% to 100%. France, Germany, Italy, Spain, Switzerland and England all saw new buds perish, the loss was compared to the 1981 and 1991 frosts.

Depending on budget, action can be taken to mitigate losses but with severe frosts the efficacy can be limited. In Burgundy for example, small vineyard stoves are the norm, also used in England, the hot air can prevent a frost forming. Wind machines an also be used, where the fans move the air to prevent frost, with a bigger budget the fanning can come from a helicopter. The use of sprinklers can also prevent frost forming

Even though Europe can reference several lethal frosts, climate change comes into plays when mild March weather and early and advanced bud break has resulted in vines being too advanced when the frosts strike. In these cases the consequences are so severe that the vines can't recover to produce a successful harvest that year.

So for 2019, lets welcome the spring equinox, the warmer weather, the longer days and grant the vines enough cool weather early on to keep those buds small and tight. Let them make it through the spring, unscathed, and above all lets hope for no late unseasonal frost.

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