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Counting Down to the 2020 Grape Harvest

From August through October, the Napa Valley is buzzing with the excitement around harvest. While tending to the grapevines is a year-round endeavor,  harvest is particularly crazy because the timing is always a bit unknown. Vineyard workers must be prepared at a moment’s notice to make sure they are picking grapes at the absolute peak of ripeness. 

To help make sure you’re ready to go, we’ve outlined the strategies and trends happening in vineyard agriculture and the tools and equipment you’ll need to get the job done efficiently.

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The Stages of Harvest in Napa Valley

How Long Does Grape Harvest Last?

 Wine Grape Harvest in the vineyards of Napa Valley can actually last up to 3 months or more. Of course, weather conditions leading up to harvest play a big part in how quickly the clusters ripen. Long stretches of hot weather, warmer than usual overnight temperatures, or significant temperature swings over a short period of time can speed up or slow down the fruit’s maturity.

When are Grapes Harvested?

The decision on when to pick is also determined by the varietal and style of wine that a particular producer is aiming for. Grapes to make sparkling wines, for example, generally get picked first, beginning in August. These and other white wine varietals ripen sooner and require a lower sugar content than some of their red counterparts.  

Berries that will be made into Late Harvest or Dessert wines tend to be left on the vine the longest to allow them to accumulate the super-high sugar content needed to complement your favorite after-dinner treats. It is not unusual for these specialty grapes to still be hanging, even after that Thanksgiving turkey has been enjoyed! 

As with many aspects of farming, harvest conditions can be unpredictable and vary greatly from vintage to vintage. So it really pays to be organized and to have your harvest equipment, tools, and supplies on-hand and ready to go well before the juice starts flowing. You never know when a rogue storm or an unexpected heatwave can force the wheels of harvest in motion.

So How Do You Know When Grape Clusters Are Ready to Pick?

Primarily it is the grape’s tannin, acid, and sugar content that determine its ripeness and are key components that influence the outcome of the final bottled product.  

Winemakers use a tool called a refractometer to measure Brix – the percentage of sugar by weight in a liquid.  Berries from multiple different locations within a vineyard block are crushed together and a sampling of the juice is placed on the refractometer plate. The refractive effects of sugar on the light will give a Brix reading on a scale that can be viewed by looking through the sight glass on the instrument.

Why Pick Grapes at Night?

The need for stability in the sugar content at the crush pad is one of many reasons why night harvesting is becoming more and more popular. The cooler temperature of the night and early morning allows for better control over the fermentation process. Aromas and flavors remain concentrated and crispness is at its peak.  

Early morning deliveries to wineries also mean that the fruit does not need to be cooled, resulting in lower energy costs and greater efficiency. Temperatures in August and September can soar during the day, making night picking also more appealing to field workers. Harvest crews often prefer to pick in the cool twilight hours.

Finally, night harvesting also helps manage logistical concerns as wineries are able to spread out the influx of fruit over a greater number of hours. Years ago when grapes were primarily harvested during the day, full gondolas of grapes might sit for hours in the heat in line at the crush pad, waiting for processing, with sugars rising and becoming unstable and aromas dissipating. For that reason,  more winemakers are requiring their growers to harvest at night.

Tools Needed for a Successful Harvest in Napa Valley

Grape harvest supplies and tools are generally available beginning in July and we recommend buying early to avoid getting stuck in a last-minute pinch when supplies are depleted.  The most common harvesting tools in stock are:

  • Bird netting
    Used to protect the fruit zone from birds and other predators while grapes finish their ripening process.
    • Side net, 42” x 5,000 feet rolls, black
    • Bread clips to secure net, 500 per stick
    • Over the top net, 14’ x 5,000 feet rolls, black
    • Over the top net, 17’ x 2,500 feet in bags, green
  • Shade cloth
    Used to provide additional shade as needed to ensure even ripening and prevent sunburn on the grape clusters.
    • 24” x 3,000 feet rolls, 40% shade, green & black
    • 24” x 3,000 feet rolls, 30% shade, white
  • Thinning shears
    Have become the most commonly used tool for removing clusters from the vine
    • Vaca, Zenport, Bahco
    • Curved blade or straight blade models
    • Serrated or non-serrated
    • Ergonomic (grey) and traditional lugs (white)
  • Lamps and Batteries
    Adequate lighting is the key to a successful night harvest, which is why most crews rely on high-powered headlamps to lead the way.


With Napa Valley’s Harvest 2020 just around the corner here, we can feel the anticipation at our office. Service and quality are the top priorities for the A&J Vineyard Supply team. With so many unpredictable elements in farming, your supply order shouldn’t be one of them.

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We know how important it is to get the right materials, on time. It’s what we demand from our own mills and suppliers, and what you should and can expect from us. Contact us today at 707-963-5354 and we’ll help you make sure your Harvest is ready!