Why one Sonoma County vineyard is seeing bud break weeks before others

Early bird bud break at Wildcat Mountain Vineyard in Los Carneros last week signaled the 2024 winegrowing season is right around the corner.

While nearly all of Sonoma County’s vineyards remain dormant, specific factors in this southwest corner of the appellation pushed grower Ned Hill’s chardonnay vines to the front of the bud break line.

“The timing of bud break is driven primarily by soil temperature, and warmer soils mean earlier bud break,” said Hill, owner of La Prenda Vineyard Management in Sonoma. “The recent rains have kept the soil wet, and wet soil retains heat, so that’s really helped speed things along.”

Although Sonoma County experienced a wet winter last year, the cool temperatures at that time pushed bud break to the middle and end of March.

“This year, the storms are a lot warmer, with lows that haven’t gone below 60 degrees Fahrenheit,” said Hill, who manages about 1,000 acres of vineyards in Sonoma Valley. “It’s definitely going to be a long growing season.”

Planted in 1998 by vintner Steve MacRostie, Wildcat Mountain is the highest vineyard in Los Carneros, where it sits on a hillside at 800-feet elevation overlooking San Pablo Bay.

During the winter, warm air rises to the top of the ridge, which has been known to encourage early bud break. But by late March and early April, the appellation’s signature fog and voracious winds return, which dramatically slows ripening throughout the remainder of the growing season.

“This site can be warmer in the winter than it is in the spring,” said Hill. “Historically, it does tend to ripen earlier than most. We haven’t seen any bud break in any of our other vineyards in Sonoma Valley, but I do think we will start to see some soon.”

Elsewhere across Sonoma County, the vineyard managers said their vines are holding tight, with no signs of bud break or the fuzzy, pre-bud break phase called “the popcorn stage.”

“I don’t think we’ll see any bud break until well into March,” said Jim Pratt, owner of Cornerstone Certified Vineyard in Windsor, which manages about 350 acres of vineyards in the Russian River Valley. “Even our early ripening chardonnay and pinot noir aren’t showing signs of fuzziness or swelling.”

Pratt added he purposely prunes his vines later in the winter season to help control when bud break occurs.

“Once you prune the vine, it tends to wake up and bud out earlier,” he said. “Some growers prune in December, but we wait until late January, February and even two to three weeks into March. That helps us prevent an early bloom, which can make the plant more susceptible to frost damage.”

Morgan Marengo, director of North Coast operations for Napa-based Atlas Vineyard Management, said Monday that he has yet to see bud break among the 2,000 vineyard acres his company farms in Sonoma County.

“The rain has slowed down a lot of people getting into the vineyard to prune, and that will likely affect the timing of bud break this year,” said Marengo, who also oversees 1,200 vineyard acres in Napa County. “I’ve seen a few vines in the fuzzy popcorn stage in the Petaluma Gap, but we still have a ways to go — especially for our older, more mature vines, which tend to bud-out a little later.”

Bret Munselle, co-owner of Munselle Vineyards in Geyserville, said there is “not even a glimmer” of bud break among his vines, a sentiment shared by grower John Balletto in the Russian River Valley and Taylor Serres of Serres Ranch vineyards in Sonoma Valley.

“We still have a lot of rain to get through before we can think about bud break,” said Serres. “If the rain stops and we suddenly get a warm spell, we could see more activity, but that is very unlikely.”

In any year, the biggest concern post-bud break is the threat of frost, which growers typically manage with wind machines that circulate warm air through the vineyard and overhead sprinklers that insulate the vines in a protective layer of ice.

But it seems we’re still a bit far off from that stage.

“It’s not uncommon for a few rogue vines to push early, like those in Ned Hill’s vineyard,” said Pratt. “But there are so many microclimates in Sonoma County that affect the timing of bud break in different areas. Nothing is uniform, nothing is straightforward, everywhere is different.”

You can reach Staff Writer Sarah Doyle at 707-521-5478 or sarah.doyle@pressdemocrat.com. On X (Twitter) and Instagram @whiskymuse.