Spring has sprung and warmth has returned to the Napa Valley. Thank goodness. It was mighty chilly for awhile at our Yountville winery. We are a bit spoiled and not used to that. Nice to see the sun and feel its heat. The tender buds are safe for now. Frost season won’t be over until sometime in late April, but it feels a whole lot more normal now than it did for the first few months of the year. Now we can concentrate on the other lesser-known crop of Napa. The cover crop. It is in full bloom now and ready to do its job in creating the perfect conditions for high quality grapes. It is vitally important.

mustard plants in grape vineyards Most visitors don’t give much notice to the cover crop during their Napa Valley wine tasting adventure, with the exception of the bright and inviting mustard fields. They lure drivers to pull off Highway 29 and wander into the tall weeds to take a trophy photo with the bright yellow mustard plants. They are beautiful and boldly colored and sometimes are over 6 feet high. You could get lost in an acre of them. But they are only a portion of the cover crop that is so important to growing great grapes. As the vines start to leaf out and the crop starts to form in the spring, these other plants have been growing for several months over the winter getting ready to perform their essential duty.

It is a lively mixture of many plants: mustard of course, vetch, peas, and a wide assortment of grasses and flowering plants. They provide a habitat for the beneficial insects that help protect the vines, they help with erosion on the hillsides, and exhibit a verdant green between the rows of vines that are just beginning to form the next vintage. Their main function is to provide nutrients for the vines. They fix certain nutrients and minerals in the soil and ultimately are plowed under or mowed in the spring so they can break down and form a natural fertilizer that will form the basis for the soil that will sustain and nourish next year’s crop.

They are a vital cog in the life cycle of a vine, yet they do their job quietly, without fanfare or much attention. All the fame and glory goes to the grapes and the wines made from them, but the cover crop is the supporting actor that gives the vines life and health at our Yountville winery.

So, the next time you are driving past a lovely vineyard in late winter or early spring, enjoy the sprouting vines and the promise of a harvest yet to come, but also marvel in the verdant beauty and workman-like contribution of the underappreciated cover crop. And by all means, get out of your car and take a picture of the amazing, dazzling mustard.