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Sonoma County Flooding: How Floods Have Impacted Vineyard Pruning This Winter

After a week-long wave of storms that dropped up to 20 inches of rain and 12 feet of snow, Northern California’s drought is officially over. According to the federal government’s U.S. Drought Monitor, January’s atmospheric river, coupled with significant rainfall last fall, has pushed Sonoma and surrounding counties into a drought-free zone for the first time since 2012. Thursday’s report in the Washington Post said 35 percent of California emerged from drought last week, a big jump from the most recently recorded: 19 percent. Just three months ago, the entire state had some sort of drought designation. As vineyard owners prepared to enter the sixth year of a historic drought, the rain began to fall in late October. It seemed as if Healdsburg had more rainy days than sunny ones; most cities in the Bay Area saw more than double their annual precipitation in the fall of 2016.

We’ve received about 12 inches of rain at Jordan Vineyard & Winery since January 3, with most of it falling in seven days; that’s quite a bit lower than parts of western Sonoma County along the Russian River, which experienced extreme flooding with 20 inches of rainfall. The river crested last Wednesday around 38 feet, which was its highest mark since 2006, when it topped 42 feet during storms on New Year’s Eve of 2005 that continued well into the new year—the most damaging floods in recent memory.

So, you might be wondering, how does flooding affect grapevines? Most rainfall in California comes during winter, when vineyards are dormant. During this phase of the vine’s annual cycle, the rain has no effect on the plant. Vitis vinifera, the types of European grapevines planted throughout California, can tolerate flooding and cold temperatures, to a degree. The vines can have “wet feet” for about 20 days of straight rain without any issues, and we only received a week’s worth. Because Sonoma County winters are mild, temperatures also rarely fall below 30 degrees, and these types of grapevines can handle temperatures down to 5 degrees Fahrenheit before the cold potentially damages the wood trunk of the plant. A bigger concern is erosion of hillsides and fallen trees, which can destroy a vineyard or impact our staff’s ability to get back into the vineyard to do the most laborious, important work each winter—pruning.

It takes our crew of five employees about three months to hand-prune each grapevine, removing almost 90 percent of its canes from the previous year. Pruning is a race against the clock. It’s a critical step for setting the balance of the crop, and it can only be done by hand. Precision is involved, and that means moving slow (watch this pruning video to learn more). Machines can be used to cut the top of the cane off, saving workers time and decreasing the possibility of shoulder injuries (see blog post about our pruning experiment), but a skilled vineyard worker must examine each vine and make decisions on which canes to cut, whittling each vine down to a two-bud spur, which should produce four grape clusters that growing season (two clusters per bud). Mother Nature hasn’t been on our side this season. We had to begin winter pruning on mornings where temperatures dipped just below freezing, and then the rain delay began. All pruning must be completed prior to bud break, which typically begins in March. More rain is in the forecast this week, putting us at least two weeks behind schedule for Jordan Estate pruning in Alexander Valley and also at the grower Chardonnay vineyards we farm in the Russian River Valley.

The good news? Drought is no longer a constant concern, reservoirs are full and the vineyards have ample moisture down to their roots, all of which bodes well for the 2017 vintage.

Other news resources on the Sonoma County flood of January 2017:

Washington Post: The drought is over in Northern California

Press Democrat: Russian River to crest Wednesday

Mercury News: California drought: Is October rain making a difference?


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Brent Young

A 2005 harvest intern who returned to Jordan full-time as viticulturist in 2008. Now Ranch Manager in charge of estate vineyards, precision farming and cattle. Spends free time showing cutting horses and restoring vintage cars, especially Woodies.

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