Suisun Valley’s mustard creates beautiful winter blanket

Our dormant Suisun Valley grape vines may be quiet and still in the winter months, but the mustard is in full bloom, creating a vibrant and mesmerizing sea of yellow flowers throughout the valley floor. 

These flowers, which arrive annually in January and February, are called mustard and they either grow wild or are planted by vineyard managers. The mustard plant, often growing between the vines, is one of the winter season’s highlights for locals and visitors alike. 

It’s easy to see and admire the mustard – just take a drive around the Suisun Valley loop. A leisure drive on Rockville Road, Suisun Valley Road, Abernathy Road, Clayton Road, or Mankas Corner Road will lead you to a bounty of yellow flowers. The mustard also thrives wild in the meadows, and lays a luxurious blanket under the trees. These “blankets” can be found in the orchards and fields all over Clayton Road and Rockville Road.

This time of year is ideal to take your camera out to Suisun Valley. Please be respectful of private property. 

The idea of planting mustard beneath the grapevines dates back hundreds of years. According to legend, a Franciscan missionary first spread the mustard seed while landscaping church properties throughout California. Planting was simple then – these early world gardeners carried the mustard seeds in a sack slung over their backs, and each sack had a small hole in it, so as they walked, the seeds scattered. 

More than just a feast for the eyes, the mustard seed is also a feast for the vines, as it thrives just until bud break, when it is turned under to mulch and provides valuable nutrients and phosphorus to the emerging grape plants.

Besides being beautiful to look at, the mustard plant also serves as an important cover crop for the vines. Mustard improves water penetration, keeps down the amount of dust on the vines and increases the amount of nitrogen in the soil. This yellow flower is also good at warding off pests. Mustard growth helps suppress nematode population. Nematodes are microscopic worms that can cause damage to vines. When soil temperatures reach about 60 degrees, nematodes can begin damaging the vines. The mustard seeds destroy the nematode’s reproductive cycle because the worms don’t like the glucosinolates in the mustard, which gives the plant its pungent odor and sharp taste. 

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