The What and How of Vineyard Cover Crops
Perhaps you’ve seen glossy pictures of vineyards with dancing wildflowers or silky grasses growing between the vines. While lovely to look at, their purpose is more than decorative. The vineyard manager is cultivating these versatile plants, called cover crops, to help improve and manage overall vineyard quality. Cover crops attract beneficial insects, increase biomass to help with erosion control, and introduce organic material into the soil.
What is a cover crop?
Cover crops are plants grown between the grapevine rows. They can consist of native plant species or deliberately seeded plants in the vineyard. These crops can be annual, biennial, or perennial. Researchers are actively experimenting with the effects of different types of cover crops on wine composition and sensory evaluation.
Examples of Cover Crops
Cover crops are typically seed mixes. Legumes are a popular choice, including sweet peas, fava beans, garbanzo beans. Legumes act to pull in nitrogen from the atmosphere and transfer it into the soil, making it accessible to the vine. When the legumes start to flower, the crop gets mowed to keep the nitrogen in the soil.
How do cover crops work?
Cover crops are one of the key principles of soil health to use plant diversity to increase soil diversity. By introducing different plant species, the grower can improve soil health.
These crops serve complex roles in vineyard management. They attract beneficial insects that are natural predators to harmful pests. Some cover crops even act as repellents to vineyard pests. Yellow mustard, for example, is a natural biofumigant used to control soil-borne pests, including nematodes, small roundworms that feast on vine roots.
In terms of erosion control, additional root material growing in between the vines helps retain soil during wet weather, a serious consideration for vineyard sites planted on any form of grade.
Cover crops require active management. During the early spring when vines are at particular risk of frost damage, cold air can settle on top of tall grasses. Instead of falling to the ground away from the new buds, the cold air pools around the buds and causes extensive frost damage.
Vineyard managers need to be aware of this risk and mow down any vegetation ahead of cold snaps.
At the end of the growing season, the vineyard manager tills the crop under. This process helps replenish and increase organic material by creating a field compost. Roots from the cover crops become food for fungi and bacteria to decompose, creating humus. The humus retains water and nutrients in the soil for the vines.
Interested in learning more? Check out the articles below on vineyard management:
Biodynamic Wine and Viticulture: Explained
Spring Vineyards: Filed Grafting
Climate Change and the Expansion of Winegrowing Regions
Or, better yet, while visiting various small wineries go ahead and ask which cover crops they use and why! They'll likely be impressed by your unique inquiry.
Author Bio: Erin O’Reilly is a Certified Specialist of Wine with the Society of Wine Educators and a long-time lover of all things fermented grape. She pens her work from Monterey wine country where she raises a glass to the growers and producers crafting wines that transcend time.