Harvest season is a big deal in the wine world – and a lot of what ends up in the bottles you drink is affected by what happens at harvest. In fact, exactly when to harvest the grapes is one of the biggest decisions a winemaker has to make in the entire winemaking process. Grab a glass and join the biddies for more information on all things wine harvesting.


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Wine Folly, Start Planning Now for the Wine Harvest Season

Wine Spectator, Harvest 101: The Basics of Crush Season

NapaValley.com, Stages of Harvest

eVineyard, Post Harvest Management

Wine Enthusiast, Grape Stomping

Study Notes for Wine Harvest:

*Please note some of these lines might be directly taken from sources noted above.


  • Takes place over 2 months each year because different varietals ripe at different times
  • Northern hemisphere is August-October and Southern Hemisphere is February-April
  • Timing the harvest is the single most important decision a grower or winemaker makes each year
  • Wine grape are much sweeter than table grapes 
    • Sweetness level determines the resulting alcohol level
    • Comes from sucrose in grapes and is measured in brix
    • Ex: Cabernet Sauvignon in Napa Valley picked at around 26-27 Brix makes a wine of about 14.5% alcohol 
    • Brix is measured with a hydrometer
  • Physiological ripeness: Just because the grape is sweet does not mean its completely ready; the seeds, skin and stems are also ripe
    • Seeds will then be less bitter and change color from green to yellowish 
  • Veraison: when the fruit hanging on the vines transforms from small, green, hard berries into what we recognize as grapes
    • Can happen any time 30-70 days, depending on variety and climate, after fruit set (when fertilized flowers have fallen off and become tiny grape bunches)
    • Lose their bright color and begin to take on mature hues (to red, purple of even almost black for red grapes)
    • Grapes soften and rapidly increase in size as the vine begins to pump sugars into the fruit
  • Unlike most farmers, grapegrowers generally seek to limit their yields 
    • If the vine is carrying fewer bunches than it is capable of the grape will ripen more fully and be higher quality
    • If a crop is too large at veraison or if ripening is delayed due to poor weather, a grower will sometimes thin the crop or conduct a “green harvest”
    • Vineyard workers will cut unripe bunche from the vines
    • Leaves can also be thinned to make sure that energy isn’t being wasted but also that the grapes aren’t being sunburned
  • Pest Busting:
    • Growers apply pesticides and fungicides
  • Ripening: Can last anywhere between 30-70 days after veraison


  • Picking: Hand harvesting is more taxing but its preferred since workers can identify the ripe bunches versus those that aren’t ready yet
    • Many big wineries use machine harvesting for efficiency
    • Harvesting often starts in wee hours of the morning (like 3 AM), want air to be at its coolest so there’s no fermenting in the sun
  • Sorting: as the grapes enter the winery they have to be sorted for quality (a proess called triage in French)
    • Traditionally the bunches are dumped on a sorting table and sorters pick through the clusters separating the good from the bad (unripe, diseased, or damaged grapes)
    • Today the grapes travel down a conveyor belt past a line of sorters making the selections
  • Crush and Destemming: allows from the yeast to get to work
    • Automated crusher detemmers break the skins open, exposing the juice and pulp but without crushing the stems and seeds which contain the tannings
    • Destemmers remove stems and this can be done before or after the grapes are crush depending on wine makers preference and the type of wine being made
      • The sooner the stems are removed, the less tannic the wine will be
    • Press separates the juice from the skins so they don’t contribute colors or tannins 
  • Grape stomping is really a thing. Evidence dating back 8,000 years, and still takes place in many vineyards today
    • Advocates say it offers more control over the wine’s flavor profile, less “full extraction” and increased skin contact
    • Less crushing of seeds – can release harsh flavors


  • Sparkling wine varietals (Chardonnay, Pinot noir) and those that you don’t want to get too high in sugar content are harvested first
    • In 2015 Mumm Napa had earliest harvest on record – July 22  
  • White wine grapes harvested next 
  • Red wine grapes typically last to allow for greater maturation, cabernet sauvignon might not get fully harvested until November (flowers a bit later and has a thicker skin)


  • After harvest vineyards tend to the vines – between harvest time and “leaf fall” is an important fertilization period
  • Depending on the climate, post-harvest irrigation may take place so as not to stress the vines
  • The non-growing season is also a time for pruning before the vines become dormant in the winter