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  • About Us
    • 50th Anniversary
    • Mission & History
    • Board of Directors
    • Our Team
    • Grower of the Year >
      • About the Grower of the Year Award
    • Lifetime Achievement Award
    • Sponsorship
    • In the News
    • Contact Us
  • Viticulture
    • Growing Season
    • Pests & Diseases
    • Soil Health >
      • Cover Crops
      • Compost
    • Vineyard Development
    • Water & Irrigation >
      • Groundwater Sustainability Plan
  • Environment
    • Air Quality >
      • Agricultural Burning
    • Ag Preserve >
      • Conservation Landscape
    • Climate Resilience >
      • Climate Video Series
      • Modern vs. Fossil CO2
      • Reduce Climate Impact
    • Wildfires
  • Resources
    • Best Practices
    • Directory
    • Grower Resources >
      • Crop Insurance
      • Financial Model
      • Tools for Grape Sales
      • Weather Alert
    • Industry Blog
    • Napa Winegrape Market
    • Podcast
    • Reports & Research >
      • Grape Crush Report
      • Napa County Crop Report
      • Growing Conditions Report
      • Soil Health Report
  • Networking
    • Calendar
    • Paso Adelante
    • Harvest STOMP®
    • ROOTSTOCK
  • Members
    • Member Portal
    • How to Join >
      • Growers
      • Vineyard Management Companies
      • Associates
  • Community
    • FOG Blog
    • FAQs
  • Donate
    • Our Donors
    • Your Impact
    • Ways to Give
    • Sip and Support Program

The FOG Blog

What the FOG: Why Are There Tarped Vine Piles in Napa Valley?

12/1/2025

1 Comment

 
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If you’ve driven around Napa Valley lately, you’ve probably spotted big piles of vineyard wood sitting out in fields, ideally, each one neatly covered with a tarp. They may look mysterious, but they’re actually an important part of responsible vineyard stewardship.

When growers remove old or diseased vines, the woody material can’t just be hauled away or left in place. Those trunks and roots can harbor pests and diseases, and transporting them off-site risks spreading harmful organisms to other vineyards. The safest and most effective way to eliminate these threats is to burn the material on-site, but to do it cleanly.

That’s where NVG’s Low Smoke Agricultural Burning Program comes in. Growers stack vine piles and cover them with tarps to keep the centers dry during fall and winter rains. Dry wood burns hotter and cleaner, dramatically reducing smoke and helping protect the Valley’s air quality. Once the piles are fully “seasoned,” growers work with the Air District and the Ag Commissioner to burn them only on approved burn days.
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So those tarped piles you’re seeing? They’re a sign of careful planning and environmental responsibility. It’s one more way Napa Valley growers protect vineyard health while caring for the land and community we all share.
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What the FOG: How Temperature Shapes Harvest

10/8/2025

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This harvest season in Napa Valley has been a study in contrasts: a stretch of classic cool mornings and bright afternoons punctuated by a few surprise rain showers that kept growers on alert. For those watching the skies as closely as the vines, this year’s weather has been a reminder of just how much temperature and timing shape the story of every vintage.

And while a little morning fog may have rolled in to keep things mysterious, Napa’s growers stayed focused and clear-headed even when the valley wasn’t.
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The Science Behind the Swing
Napa Valley’s Mediterranean climate is built on balance: warm, sunny days to ripen the fruit and cool nights to preserve its natural acidity. These diurnal temperature swings, often reaching 30–40°F between afternoon and pre-dawn, are what give Napa wines their structure and energy.

Daytime warmth drives photosynthesis, helping vines convert sunlight into sugars. As night falls, respiration slows, keeping acid levels intact and locking in the brightness that defines a balanced wine. It’s a delicate rhythm—and when the weather shifts, even slightly, growers adjust in kind.
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Timing the Perfect Pick
This year’s early October rains briefly slowed harvest, adding an extra layer of strategy. Some growers raced to bring in early-ripening varieties before the clouds rolled in; others held steady, knowing the moisture could help refresh canopies and settle dust without harming quality.

Temperature remains the guiding factor even amid unpredictable weather. On cool mornings, grapes come in firm and vibrant; on warm days, the picking window tightens. Many crews began before sunrise this year to ensure fruit arrived at the winery cool, fresh, and bursting with flavor.

Consistent cool nights following those brief rain events allowed flavors to continue developing without spikes in sugar, helping preserve balance and freshness. The result will likely be wines of moderate alcohol, vibrant acidity, and expressive fruit—hallmarks of a beautifully tempered season.

And as the fog lifts on another Napa Valley harvest, one thing remains clear: excellence always rises with the morning light.
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What the FOG: Why Grapes Change Color at Veraison

7/16/2025

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Every summer, Napa Valley vineyards stage a stunning transformation: grapes begin to change color in a process called veraison (that’s ver-ay-zhun, if you want to impress your friends).

But what the FOG is actually happening?

At veraison, grapes switch from growth mode to ripening mode. Until this point, berries are firm, green, and loaded with organic acids, but not much sugar. Then, as veraison begins, the chemistry inside each berry shifts dramatically:
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​🍇 For red varieties: Green chlorophyll breaks down and anthocyanins (natural pigments) accumulate, giving berries their deep purple, red, and blue hues.
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​🍇 For white varieties: While they don’t turn red, they lose their bright green tint as chlorophyll fades, and take on a warm, golden glow thanks to carotenoids.
​This color change is more than just a pretty picture—it’s a visible sign that grapes are softening, sugars are rising, and flavors are developing. The vine is investing energy into making berries attractive to birds and animals (nature’s seed dispersers), but in Napa Valley, we’re paying close attention for another reason: harvest is inching closer.
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​And, of course, Napa Valley’s famed fog plays a quiet but critical role in this process. Those fog-cooled mornings temper the heat of summer days, slowing sugar accumulation and preserving the natural acidity that gives our wines their vibrancy. You could say the fog helps grapes find their best light—without overexposure.
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So next time you stroll past a vineyard and see berries turning color, know that you’re witnessing a fascinating natural shift—and that Napa’s growers are watching carefully, guided by experience, stewardship, and maybe just a little help from the morning fog.
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How Vineyard Irrigation Works

7/1/2025

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​Summer is here, and while the valley is basking in sunshine, we’re here to clear the fog around one of the season’s most essential vineyard practices: irrigation. Even though vineyards might look lush and green, you might be surprised to learn how little water they actually use compared to other crops. With every drop counted, growers rely on precision tools and careful stewardship to ensure vines get just what they need—and not a drop more. So let’s lift the fog on how Napa Valley growers keep their vines hydrated while protecting this precious resource for our entire community.

Why Vineyards Use Less Water Than Other Crops

  • Vineyards use drip irrigation, which delivers water directly to each vine’s roots, unlike other crops that often rely on sprinklers or flood irrigation.
  • Napa growers closely monitor soil and plant conditions to decide exactly when and where to water, rather than watering on a set schedule.
  • Grapevines have deep root systems, allowing them to access moisture far below the surface, so they require less frequent irrigation.
  • Thanks to efficient practices, most Napa vineyards now use 30–50% less water than they did a decade ago, a significant reduction compared to many other irrigated crops.

What This Means for Our Community

  • Sustainable water stewardship: Vineyards contribute to watershed health by limiting runoff and using less water than row crops or landscape irrigation.
  • Adaptive to drought: Napa growers are committed to refinement—they continually improve tools and practices to adapt to climate stress.
  • Shared benefit: Conserving vineyard water supports local waterways, wildlife habitat, and community water supplies.
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What the FOG is Springing Up in the Vineyards?

5/20/2025

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​If you’ve driven past a vineyard lately and spotted folks darting between rows like grapevine whisperers, you’re not imagining things--May and June are some of the busiest months of the growing season. Crews are out early and often, walking the vines, checking progress, and giving the plants the TLC they need to grow into this year’s vintage.

There’s no slowing down now—this is the season of bloom, fruit set, and serious vine wrangling. Everything that happens in the next few weeks sets the stage for the grapes you’ll be sipping in a bottle down the road.
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Let’s de(mist)ify the action unfolding out in the vineyards right now, because it’s full steam ahead in the fog and sun!
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Late spring means grapevines are flowering—yes, they bloom! Tiny, delicate blossoms appear where grape clusters will eventually form. These aren’t showy like roses, but they’re critical. Each flower has the potential to become a grape… if the conditions are just right.

Foggy Fact: Too much rain, wind, or chill during bloom can mess with pollination, leading to something growers call "shatter"—when some grapes just don’t form. It's nature’s way of editing, but it makes vineyard managers bite their nails.
With proper vine nutrition and the right weather conditions, we get to fruit set—when those flowers transform into teeny tiny grapes. Think of it as the “baby bump” phase of the vine’s growing season. Right now, growers are walking the rows daily, checking how things are setting and watching the weather like hawks in raincoats.
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Spring growth is wild. Vines shoot out like they’re training for a marathon, and growers need to tuck and train them into neat rows so sunlight and airflow can do their jobs. This is called shoot positioning, and it’s like teaching a bunch of overenthusiastic kids to stand in a line for recess.
This helps prevent disease and ensures even ripening later on. (Sunlight = sweet grapes.)
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Birds in the Vineyard: Nature’s Pest Patrol with Feathers and Flair

5/20/2025

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If you’ve ever wandered through a Napa vineyard and heard a cheerful chorus of birdsong, you were likely listening to some of our hardest-working vineyard partners. That’s right--birds do more than just tweet and flit through the vines. They’re a vital part of sustainable grape growing in the Napa Valley.

Why Birds Belong in the Vineyard
From bluebirds to barn owls, a wide variety of bird species call our vineyards home—and for good reason. Grape growers invite them in! By providing safe nesting sites and preserving natural habitats, growers are encouraging birds to stick around. And that’s not just good for the birds—it’s great for the grapes.

Here’s the scoop: many birds love to snack on insects, rodents, and other vineyard pests. Instead of relying on chemicals, Napa growers often take a natural approach to pest control by welcoming birds as part of the team. Think of them as feathery farmhands, quietly keeping things in balance.

But let’s not wing it— not all birds are vineyard heroes. Flocking birds like starlings, blackbirds, and cedar waxwings can damage fruit and become pests, which is why growers sometimes need to use bird deterrents responsibly and in line with local regulations—to keep things clear and avoid flying into a fog of trouble.
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Bird Boxes: Tiny Homes with Big Impact
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​This June, FOG is bringing the bird buzz to the Napa Farmers Market on the second Saturday with a fun, family-friendly activity: bird box decorating! Kids (and kids at heart) can get crafty while learning how bird boxes create safe spaces for nesting. These cozy shelters help support bird populations, especially species like Western Bluebirds that are known to help reduce bugs that munch on grapevines.

Whether you take your decorated box home to hang in your backyard or donate it to a local vineyard, you’re helping the ecosystem—and getting a closer look at the thoughtful ways growers care for their land.

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What the FOG: Why Wind Machines Matter in Napa Valley

3/5/2025

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​If you've ever been woken up by the low hum of wind machines on a cold spring night, you're not alone. These towering fans play a critical role in protecting Napa Valley’s vineyards from devastating frost damage, ensuring a successful grape harvest each year. While the noise can be surprising, the benefit they provide to local agriculture is immeasurable. Here’s why wind machines are an essential tool for our growers:

1. Wind Machines Prevent Crop Loss & Protect Local Agriculture
Frost can be disastrous for vineyards, especially in the early spring when tender grapevine buds are emerging. Just a few hours of below-freezing temperatures can destroy an entire season’s crop, leading to significant financial losses for farmers and impacting the wine industry. Wind machines help prevent this damage by maintaining a stable temperature around the vines, reducing the risk of frost-related destruction.

2. Wind Machines Use Natural Air Movement to Prevent Frost
On clear, still nights, cold air settles at ground level while a layer of warmer air sits just above it—this is called a temperature inversion. Wind machines work by pulling that warmer air down and mixing it with the cold air near the vines, raising the overall temperature and preventing frost formation. Unlike water-based frost protection methods, wind machines do not require large amounts of water, making them a sustainable choice, particularly during drought years.

3. Wind Machines Run for Just a Few Hours to Save an Entire Crop
We understand that wind machines can be noisy, but they typically operate only for a few hours during the coldest parts of the night—just long enough to protect the crop. Without them, frost could cause long-term economic losses, impacting not only farmers but also local businesses, wineries, and the entire community that depends on a thriving wine industry. Their short-term use yields long-term benefits, ensuring a sustainable future for Napa Valley agriculture.

Wind machines are a key component of responsible vineyard management, helping growers navigate the fog of unpredictable weather while reducing reliance on water-intensive frost protection methods. The next time you hear them humming in the night, know that they’re clearing the air and safeguarding the vineyards that make Napa Valley’s wines some of the best in the world.
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What the FOG?! Erosion Control

12/10/2024

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De(mist)ifying what’s happening in the vineyards around us
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This vineyard is preparing to lay out straw mulch.

Have you ever noticed how Napa Valley’s hillsides rarely wear a bare patch of soil?

That’s no accident. Just as golden grasses blanket our hillsides in summer, erosion control measures protect our vineyard soils during the rainy season. Straw mulch, for example, shields bare soil from pounding raindrops, preventing the nutrient-rich topsoil from washing away. You might also spot straw wattles lining slopes—these barriers slow and disperse water, giving it time to soak into the ground while keeping sediment from traveling downhill.
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When vineyards are redeveloped, Erosion Control Plans are created by expert civil engineers who understand the nuances of Napa’s terrain. These plans are then implemented by vineyard management companies or in-house farming teams who know every inch of the land. Together, they ensure the soil is protected while promoting clear, healthy watersheds.
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These measures are not just a safeguard for today but a vital preparation for the future. As intense rainstorms become more common with shifting climate patterns, erosion control is key to keeping our soils and streams resilient. It’s just one more way we let nothing—including precious soil—slip through the fog.

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The Scoop on Compost: Turning Vineyard Waste into Black Gold

12/10/2024

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​Now we’re talking about black gold! Composting is a vineyard practice that has grown in popularity from Carneros to Calistoga, and for good reason—it’s a sustainable way to give back to the soil and support a healthy vineyard ecosystem. Rich in organic matter and teeming with microbes, compost boosts soil health by encouraging microbial activity and improving the structure and fertility of the soil.
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​In Napa Valley, spent grape skins and seeds—called pomace—are often recycled into compost after being pressed at the winery. Some vintners even make their compost onsite and return it to their vineyards in the fall, creating a perfect farm-to-farm cycle. Compost can be spread across the entire vineyard floor or applied directly beneath the vine rows, depending on the vineyard’s needs.

Many vineyards follow a composting rotation, applying about 5 tons per acre every three years. However, struggling blocks or soil needing extra attention might see compost applied more frequently or at higher rates to give it a boost.

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Cow and sheep manure is a valuable addition to compost, adding nitrogen and other nutrients that fuel the composting process. Photo by Sarah Anne Risk

​​You might have also heard of compost tea—a liquid version of compost created by steeping it in water with added oxygen for about 24 hours. The result is a microbe-rich liquid that can be added to drip irrigation systems throughout the year, providing a steady dose of beneficial microbes to the soil and vines.

Want to dive deeper into the science behind compost? Dr. Elaine Ingham, a renowned soil microbiologist, has dedicated her career to understanding the soil food web and its importance in healthy farming practices. Check out her website at soilfoodweb.com for tips, methods, and everything you need to know about composting.
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From boosting soil fertility to reducing waste, compost truly is the black gold of Napa Valley vineyards—and it’s a shining example of how sustainable practices can support world-class grape growing. 🌱🍇
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Learning about compost from Yount Mill Vineyards at the 2024 Organic Winegrowing Conference.
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From Fog to Flora: How Cover Crops Keep Vineyards Thriving

12/10/2024

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It’s rare to see a vineyard without a lush green carpet of plants sprouting after the first rains of fall. These plants, called cover crops, are intentionally planted between vineyard rows, and they’ve become a standard practice in Napa Valley—for good reason. Cover crops provide a host of benefits that support healthy vineyards and the environment, all while looking beautiful in the winter fog.

So, what do cover crops actually do? Think of them as nature’s multitaskers. They help rainwater soak into the ground more effectively, keep the soil in place, and boost soil health by adding organic material. Some cover crops, like legumes (think peas and beans), even pull nitrogen from the air and store it in their roots, creating a natural fertilizer for the vines. This helps keep the vineyard healthy without needing extra chemicals.

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​In vineyards where the vines grow a bit too vigorously, grasses might be planted. These grasses use up extra water and nutrients, balancing vine growth. They’re often left to grow and then mowed, with some reseeding themselves for next year—less soil disturbance, more long-term benefits.

Finally, flowering cover crops like wildflowers provide a feast for beneficial insects, keeping the vineyard buzzing with biodiversity. These helpful bugs can naturally reduce pest problems, creating a healthier ecosystem. Plus, a vineyard in bloom under the morning fog? It’s a picture-perfect way to show how farming can work hand-in-hand with nature.
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Cover crops are just one of the many ways Napa Valley’s growers work to care for the land year-round, proving that excellence in farming isn’t just clear-cut—it’s often foggy!

Learn More About Cover Crops
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In October, NVG handed out free cover crop seeds at the Napa Farmers Market. They encouraged community members to plant these seeds in their home gardens to improve soil health, conserve moisture, and support pollinators, bringing sustainable farming practices into their own backyards.
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    ​​The FOG Blog is your go-to guide for understanding the growing season in Napa Valley—no farming degree required! We lift the mist on vineyard care, seasonal practices, and sustainable farming, breaking it all down in simple, easy-to-digest terms. Whether you're a wine lover or just curious about what happens in the fields, the FOG Blog will keep you informed and connected to the land behind the vines.

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