Though pruning crews have been out in the California North Coast's prized vineyards since early this year prepping the plants, it's at the first signs of new growth that the new growing season begins. And local growers Monday said "bud break" is upon us in the warmer areas of the region.

Growers often say that the outcome of the previous harvest sets the vines up physiologically for the next harvest. The official tally of the 2018 harvest is still a month away, but the North Coast haul is expected to be larger than 2017. The value of the North Coast wine grape harvest that year was $1.5 million.

“Buds on chardonnay in the Carneros AVA are swelling and bursting,” said Brittany Pederson, viticulturist at Renteria Vineyard Management, in Napa Valley Grapegrowers' announcement of the new season that quotes several members of the trade group. “These are the first signs of bud break. In the weeks to come, when the weather gets consistently warmer, the sap will start flowing and the vines will be woken up. Bud break will really start to take off then.”

This early stage of the season is about a week and a half behind the pace last year because of the winter rains, according to Allison Cellini Wilson, viticulturist at Cliff Lede Vineyards. The valley received an average of 35 inches of rain between November and February, the association said.

“The soils have already absorbed all the water from the winter rains. We’re not seeing any stagnant water remaining out in the vineyards, which means our soils needed the saturation,” Cellini Wilson said.

The trade group noted that the springtime temperatures and ample water that have moved the grapevines to this point also have spurred growth and blooming of mustard and other vineyard cover crops.

“The cover crop has grown in well and is looking very healthy," Pederson said. "Right now, we’re in the vineyards preparing for the 2019 growing season, which includes cover-crop management, tracking nighttime temperatures for frost potential, and wrapping up pruning.”

Done throughout the first three months of the year, pruning creates vine balance, influencing grape yields and fruit quality, according to the association. Pruners remove 70 to 90 percent of the previous year's growth, leaving select cane or spur positions are left. The skill required for pruning vines that produce high-end wine was shown off during championships in Napa and Sonoma counties last month.

New growth breaks through the remaining buds on the vine, resulting in new growth and the start of the growing season.

“To start the growing season off with full reservoirs and soil profiles is ideal," Cellini Wilson said. "Everything thus far is looking great and we anticipate a busy 2019 growing season.”

Sonoma County farmers have been seeing the first greenery of the new growing season since early March.

“It has roughly been going for a week to 10 days,” John Buchar, who farms 55 acres on his Healdsburg ranch along the Russian River Valley, told Bill Swindell of The Press Democrat on Monday. He noted that pinot noir and chardonnay vineyards in some areas — such as those on hillsides with greater sun exposure — have had their woody vines awaken after being dormant over the winter. Others will need more time over the next weeks.

“I’m sure we are going to see more with the warmer weather,” said Bucher, who also produces wine under his Bucher Wines label.

Charles M. Schulz-Sonoma County Airport reached a high of 76 degrees on Monday, though a cooling trend with rain will come into the area for the rest of the week.

Areas around the Carneros region near San Pablo Bay, which has a milder climate, are typically the first to experience bud break, growers say. It then will spread across the whole county, from Alexander Valley in the north to Sonoma Coast in the west.

“We saw the first signs of bud break about two weeks ago. Now, all of our early blocks are showing green leaves. The rest of the acreage has swelling buds and will break soon with this warm weather,” Mike Crumly, vice president of vineyard operations at Gloria Ferrer Caves & Vineyards just south of Sonoma, said in an email.

Growers in the Napa Valley also reported bud break activity in the southern part of the county. “These are the first signs of bud break. In the weeks to come, when the weather gets consistently warmer, the sap will start flowing and the vines will be woken up. Bud break will really start to take off then,” Brittany Pederson, viticulturist at Renteria Vineyard Management in Napa, said in an email.

The timing of this year’s bud break is much more typical than the region experienced in 2018, when it occurred about a month earlier.

“We are right on schedule for this,” said Karissa Kruse, president of the Sonoma County Winegrowers trade group. “The vines are coming back. ... Renewal is happening.”

The region received a considerable amount of rainfall over winter. Since the current rain season began on Oct. 1, Sonoma County has received 38.29 inches of precipitation at the airport through Monday, an increase from a historical average of 30.40 inches during the same time period.

That rainfall has allowed vineyard soil to absorb the water and store it for subsequent hotter months. The precipitation also has allowed reservoirs to be filled on many properties, which can be used for frost protection in coming months.

Some may have noticed above-ground sprinklers spraying water on vines across the county in recent weeks. Growers are spraying to relieve pressure on reservoirs that are beyond capacity as well as to test out sprinkler systems to ensure they work, said Kruse.

When overnight temperatures near 32 degrees in the spring, vineyard managers spray vines with water to coat the fragile shoots in a layer of ice that will protect them.

“You have to test the thing before frost happens,” Kruse said.

This story has been updated with details from Sonoma County and 2017 grape crush data.