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On the Bottle: How Grapes Grow, from Root to Fruit

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Joseph Phelps Vineyards in Napa Valley, California

Today we shift our focus to the humble grape and explore how this fruit of the vine comes into the world, grows to ripeness, and ends up in our glasses: It’s the life cycle of a vine in the Northern Hemisphere, presented in five acts.

ACT I: Bud Break

  • In March, or whenever daily temperatures get above 50 F, little green buds will form on the grapevine. Shoots begin to grow from these buds in about a month. Vineyard managers might be concerned with doing two things at this stage: Pruning away some buds to reduce the vine’s output (thus increasing the quality of the grapes) and protecting the buds from frost damage if temperatures should dip below freezing. If you’ve ever seen a giant fan – or a seemingly random small fire - in a vineyard in the springtime, now you know those are two methods used to heat air or move cold air away from the vines in case of frost.

ACT II: Flowering and Fruit Set

  • If all goes well weather-wise and temperatures are in the 60s F, by May or June there will be tiny flower clusters on the new green shoots. These will grow so that individual flowers separate, self-pollinate, form a grape seed, then form the berry that surrounds the seed. I hope it doesn’t shock you to learn that all grapevines are hermaphrodites; I just think of them as self-reliant. Vineyard managers have to hope that no severe weather or vine disease ruins the flowers at this stage, because no flowers means no fruit.

ACT III: Véraison

  • When grapes first form in late spring, they are small, hard, green, and extremely tart. By July or August, they will have begun to ripen and change to their true colors, whether that’s red or black or yellow or grey. The French have dubbed this moment of color change “véraison,” and it is quickly followed by the grapes growing plump, sweeter, and less acidic. Weather is key but vineyard managers can affect how early this happens – and earlier is better, to allow maximum time to ripen before the weather turns cool again – by controlling the amount of water the vines get and pruning the leaves to allow more or less sunshine to reach the fruit. As long as the grapes remain on the vines – that’s the “hang time” – they’ll need to be protected from pests of the viral, fungal, insect, and animal variety with an assortment of treatments and physical barriers.

ACT IV: Harvest

  • Grapes will get picked by hand or machine in September or October, excepting those few varieties to be used for late harvest dessert wines. Vineyard managers and winemakers will work together throughout the season to monitor the grapes’ sugar ripeness (sweetness), phenolic ripeness (physical development of seed, skin, and fruit), and weigh the likelihood of any adverse weather conditions to choose ideal harvest times for each parcel of grapes. There are all manner of methods at their disposal to determine these things, from high-tech laboratory tests to consulting lunar calendars.

ACT V: Dormancy

  • After harvest time, the grapevine’s leaves will yellow and then fall after frost sets in, and the vine will go dormant for the winter. They’re just napping, not dying: Grapevines typically produce quality fruit for a vintage two years after being planted or grafted onto existing rootstock, and they will keep producing for decades if kept healthy. (Vines over a hundred years old are not unheard of in longstanding wine regions, and as they bear less and less fruit each year, concentrating the flavor in each grape, wines made from old vine fruit are highly prized…and priced.) Winter vineyard maintenance can include some pruning, rooting up unproductive vines, or preparing new sites for planting, but most of the work happens inside the winery this time of year.

That's the life of a grape in a nutshell. In a grapeskin?

"On the Bottle" is a column about wine and spirits appearing every Friday on the Martha Stewart Living Radio blog. Email your boozy questions and wine quandries to radio@marthastewart.com and they'll be answered in a future post.

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