Every winter, while the grape vines are dormant, wild grasses and flowers awaken and thrive in the chilly, wet environment. In the earlier part of winter, the grasses grow in many shades of green, but beginning in late January, mustard flowers paint the hills bright yellow, in stark contrast to the dark brown vines. In February, wild radish appears with its varied soft pinks, whites and purple blooms and soon after, chamomile flowers blanket the landscape in snowy white.

Some of these wild plants are cultivated as vineyard cover crops, and contribute organic matter, nitrogen and other nutrients to the soil. They also help contain soil erosion from the heavy winter rains, and provide a habitat for beneficial insects and birds such as ladybugs, spiders, owls, and other critters. Cover crops often consist of grains like barley and oats, legumes such as peas and bell beans, as well as mustard, vetch, clover, chamomile, and wild radish.

In late spring, cover crops are often tilled into the soil to provide nourishing organic matter, and to eliminate interference with budding grape vines.