Vineyards are a lively, colorful place in the Spring, Summer and Fall; changes are apparent everywhere you look. It’s easy to think of Winter as an off season where not much happens.
While the excitement engendered by green growth, bloom and full lush lobes of fruit is completely absent, and little more than leafless vines, and perhaps a blanket of snow greet visitors, there’s a lot happening.
The time after harvest is an essential period during which vines recover, mature and prepare their renewal buds for the Spring. Roots dig deeper, sometimes going through growth spurts just before dormancy, in preparation for the season of quiet.
That time of stasis happens when days start late and end early, temperatures drop, animals and insects slumber, food is scarce. Vines shed leaves, stop producing energy through photosynthesis and instead rely on stored energy in their roots to get them through.
There are a number of steps vine-growers in warm and cool climates should take to keep vines fit and healthy for next year’s cycle of life. Read on for a cheat sheet to ensure that vines have an opportunity to heal and gather strength for the three essential seasons of hard work ahead.
Winterizing Tips for All Vineyards
Winter, first and foremost, is an opportunity to refresh and rejuvenate the soil.
Great wine doesn’t come from poor soil. In recent years, it has become increasingly clear—amid the climate change-induced temperature fluctuations, hail storms, wildfires, floods and prolonged droughts that have devastated wine regions across the world—just how important a healthy level of bioactivity is necessary for soil fertility and high-quality, higher-yielding, terroir-driven wine. (For those who want to take a deeper dive into the benefits of soil health, an excellent resource for learning more about the importance of vigorous soil is “Growing a Revolution: Bringing Our Soil Back to Life,” by geologist David R. Montgomery).
One of the most tried-and-true routes to healthier soil is through compost application during the winter months. Studies show that vineyards treated with compost show 20% to 40% higher levels of microbial levels and organic matter levels 15% to 100% higher than untreated areas. Those microbes not only provide nutrition to the roots and vines, but they fight off disease-bearing pathogens. Healthy soil also leads to greener foliage, fewer nutrient deficiencies and hardier constitutions year-round.
Compost (comprised of manure, discarded grape skins, old vine trunks, wood mulch, pomace and regional-specific items like oyster shells or hay), and in the case of vineyards using biodynamic preparations, teas, can be spread across the vineyards. (Check out this explainer from Jordan Vineyard Manager Dana Grande on how to make organic compost). Fertilizers—organic or synthetic—can also be added, as a kind of vitamin smoothie for the resting vines.
After compost has been applied, it’s time to prevent the erosion issues that can accompany Winter rains. The best way to do this is to bring in straw wattles. Correct installation is key; brush up with this guide from the Napa County Resource Conservation District.
This is also the time to prune vines, tie up nets, hill up vines and test soil health. When the last leaf has fallen, pruning can commence. The practice shapes future yields, supports vine growth and prevents the spread of disease. Without the protective camouflage of leaves and grapes, it’s easier to spot infections and dead vines.
Assessing soil health and measuring nutrient levels will help determine what kind of cover crops will be needed for the coming season.
Winterizing the irrigation system is also a necessary step to take, not only because the colder months are typically wetter than others, but also because water lines can be severely damaged by frost. All systems should be cleared of water, and the pumps should be turned off.
For Cool Climate Vineyards
Vineyards in cool climates need extra doses of TLC to help protect them from the harshest effects of the winter.
As climate change shifts weather patterns across the world and year-round, even regions where frost and snowfall wasn’t previously an issue, have been dealing with extreme storms, sometimes well into early Spring.
One way to protect grapevines from deep freezes is with 20 cm, or about 8 inches, of soil. The soil acts as a blanket for these shivering, exposed vines. The coldest regions should add additional blankets of straw or water-resistant corn stalks. Winegrowers often weigh down the straw and cornstalks with stones and logs, so they don’t blow away.
Covering the vine bases with mulch can also be done, but it is not ideal because it can attract rodent populations that will then go on to munch and damage the trunks.
It goes without saying that the best way to ensure a vineyard’s health and success year-round is by starting with the right varieties for the place. This overview from UC Davis provides an excellent basis for choosing the right variety, clone and rootstock for the site. It also provides tips on vineyard selection and ways to ameliorate the effects of climate change.
Terraview’s proprietary suite of tools helps vineyard managers across the globe improve yields, reduce costs, assess soil health and predict weather with one dashboard of tools. Try Terraview for free this Winter, and see how much technology can improve the health of your vineyard, and your bottom line.