Marvelous mustard: How these golden blooms help North Bay vineyards, pastures
Drive along Petaluma Hill Road from Santa Rosa to Rohnert Park in Sonoma County and the rolling meadows to the west are shimmering with it.
Ride a bicycle through the backroads of Dry Creek Valley and the dark, gnarly zinfandel old vines contrast starkly with the yellow brilliance of it.
A tour of the Silverado Trail shows wave after wave of the uncontested harbinger of spring growing in profusion among the rows of Napa Valley’s wine estates. It’s even found in profusion between Highway 12 and Third Street as you head to Imwalle Gardens to buy vegetable starts.
It is mustard time in the North Bay.
From the end of February through March the plants grow fast and furious, serving as the backdrop for many a calendar shot or wedding portrait.
Some vineyard managers plant mustard for more than its magnificent gold and yellow hues, however. This aesthetically pleasing cover crop has supreme value as a “green manure.” When the weather warms and the mustard plants begin to set their seeds, the vineyard workers mow it down, and either let it lay where it drops or till it under to do its nourishing magic deep underground.
Mustard is planted in the fall in our region. Sometimes it will be sown to refresh a fallow field, growing an average of five to six feet, or even higher. The hardy mustard seeds can survive in the soil for up to forty years and burst into life after a late rain.
Cover crop seed mixes consisting of members of the brassica family, such as mustard and radishes, are valuable for a host of reasons.
When planted on sloped grades, they prevent erosion and decrease nutrient runoff. Mustard retains soil moisture, recycles nitrogen, reduces weeds because of its early vigor and fast growth, and attracts a variety of pollinators with its bright blooms. These attributes of the plant interest farmers and gardeners who wish to improve overall soil health, but for the health of the growing wine grapes, there is an additional benefit.
Mustard plants help suppress the nematode population — microscopic worms that can damage vines — because mustard contains high levels of natural chemical agents called biofumigants.
The best types of mustard to grow are those with high levels of Glucosinolate, the extra spicey compounds that give mustard seed that slight pungent taste and further deter the roundworms.
Examples include black mustard, ida gold mustard, oilseed radish, daikon radish and wild radish. The seeds are so hot they repel insects. Reducing these harmful organisms by natural means spares our vineyards the harm done from artificial eradicators and dangerous pesticides.
Cutting the mustard
Kelly Boyer has been working at LeBallister’s Seed and Fertilizer for nearly 20 years. A former educator with an ag business degree from California Polytechnic University, she has assumed the general manager role from her father, Tom Hendrickson, now 79.
In 1947, Hendrickson’s grandfather, George LeBallister, bought a Sebastopol apple ranch, where, in addition to packing apples, he sold agricultural chemicals and fertilizers on the side. In 1980, Hendrickson purchased his grandfather’s inventory and five years later he expanded to include seeds and seed equipment.
Today LeBallister’s sells about 50% seed and 50% fertilizer. The family-owned business specializes in creating custom seed mixes and offering consulting services from a facility located on Sebastopol Avenue in Santa Rosa.
“We have always sold mustard as a cover crop, but there has been an uptick in the last five to eight years because of interest in sustainable farming,” Boyer says.
Like home improvement stores and other agriculture-related businesses, the company has been open and consistently busy all during the pandemic.
“We sell about 95% to the vineyards, but small farms, big farms, home gardeners all want these seed mixes for prepping the ground. Mustard’s deep taproot helps break up our area’s clay soils.”
Besides being prolific and quite adept at reseeding itself, Boyer says mustard is appealing because of its price. “It’s $1.50 a pound, and you use 15-20 pounds an acre. By comparison, poppies are $15.50 per pound.”
Boyer notes that mustard wasn’t always planted as a crop to grow and sell.
“It was considered a weed, the bane of the farmer’s existence because it got in the way of the hay they were trying to grow. To them the thought of planting mustard on purpose was a little crazy.”
One winery official who asked not to be named wrote, “The majority of the mustard in our vineyard is naturally reseeded. It does indeed look beautiful, but it is essentially a prolific weed with benefits: preventing erosion, discouraging nematodes and creating fantastic backdrops for photos. We don’t consider it a highly important aspect of our wine production.”