California

These factors remain fairly similar year to year. Daily variations account for weather patterns, which can create vintage variation over the course of an entire growing season. The terms macroclimate, mesoclimate, and microclimate are further used to specify climate and viticulture. 

Macroclimate

The overall climate of a region which is usually a large geographic area. For example, the microclimate of much of coastal California is Mediterranean.

Mesoclimate

Refers to the climate of a particular place such as a specific vineyard site.  

Microclimate

Refers to the specific conditions in a smaller section of a vineyard, even rows of vines. 

Volcanic Soils

Can be found in places in Northern California where volcanic eruptions took place over 30-million years ago. In particular, volcanic soils can be found in the Red Hills AVA of Mendocino County, as well as the Vaca Range and Mayacamas Mountains that frame Napa Valley. Here, red grapes such as Cabernet Sauvignon and Merlot do well and the wines are deep, concentrated, and powerful.

Alluvial Soils

Are commonly found in and around rivers and watershed areas. Over the millennia many of these rivers have carved out valleys, and loose weathered rock, gravel, and soil have washed downhill, forming colluvial deposits. Napa Valley and Sonoma’s Russian River Valley are known for alluvial soils. Bordeaux varieties as Cabernet Sauvignon and Merlot grow well in alluvial soils.  

Colluvial Soils

Are formed at the base of hillsides by running water, the slow downhill settling of rocks and soil over time, or a combination of both. Colluvial soils are made up of a range of different sediments and rock types. Bordeaux varieties, Sauvignon blanc, and Chardonnay, thrive in these soils. 

Calcareous

Chalky or calcareous soils are based on decomposed limestone from the fossilized remains of ancient sea creatures. Calcareous soils are well suited to viticulture because of their water retention and drainage properties. In California, calcareous soils can be found in much of the Paso Robles AVA. Here Rhône varieties such as Grenache, Syrah and Mourvèdre thrive. I

Sand

Sandy soils retain heat and are well-drained. They are also resistant to vine pests such as phylloxera. Sandy soils are found throughout California in places such as Dry Creek Valley AVA in Sonoma County, the Lodi region, and parts of Monterey County. Sand also mixes with other soil types such as loam and calcareous. A number of grapes, including Chardonnay, Pinot noir, and Zinfandel, all thrive in sand-based soils and variations. 

Loam

Loam soils are a blend of silt, clay sand, and humus. Loamy soils are overly fertile and often create vigor and overcropping problems in the vineyard, necessitating frequent pruning. Sandy loam soils are found in places such as Sonoma Valley, Napa Valley, and Monterey County. Grapes such as Chardonnay, Sauvignon blanc, Pinot noir, and Merlot do well in sandy loam soils.

Further, the vines are easier to prune, maintain appropriate canopy management, and harvest. Yields from vineyards planted on flat expanses tend to be higher, as the soils are richer in nutrients leading to more vigor. Vineyards planted on hillsides typically must be worked by hand, increasing labor and costs. Further, yields are usually diminished because hillside soils are often meager and nutrient-poor. However, wines made from hillside vineyards are known for their concentration and unique qualities. 

The aspect of the vineyard is also important. The optimum aspect of vineyard rows is north or south to maximize sun exposure on both sides of the vine canopy. Other vine row arrangements also work well. However, managing the canopy requires far more attention, detail, and work. For example, vineyards facing east experience morning sunshine but are in the shade during the long hours of sunlight in the afternoon and evening. Here the east-facing canopy must be open, with the vines protected by foliage to the west. The opposite is true for vineyards facing west that get little if any morning sun while being fully exposed to extended sunshine in the afternoon.

Traditionally, vineyards in California were set up to have vine spacing at 8 feet by 12 feet (2.5-3.6 m), with approximately 450 vines per acre (0.4 ha). This spacing allowed easy access for tractors and other equipment needed to work the vineyards. However, from the 1980s onward, row spacing became narrower as newer, smaller farm equipment was developed. Over time vine density also increased dramatically, ranging up to several thousand vines per acre (0.4 ha). Depending on the specific grape variety, high-density vine spacing can be as compact as 4 feet by 4 feet by 2.5 feet. Greater vine density allows vineyardists to decrease yields by up to half, maintain the same overall crop load, and increase quality of the fruit while maintaining healthy vines.

Roots

Or root systems anchor the vine. They also affect vigor and transport water and nutrients to all parts of the vine.  

Trunk

Is a former shoot that has become permanent and supports all the leaves, stems, flowers, and fruit. Root systems uptake water and minerals to the vine helping it grow and produce grapes. 

Shoots

Are the primary growth of the vine and made up of the stems, leaves, tendrils, and eventually the fruit. Pruning and other vineyard work is concerned with controlling the shoots. Canopy is the term used to describe the arrangement of the vine’s vegetative output. 

Buds

Are points of growth on a vine that develops at the axils, or the place where a branch is connected to a stem. At bud break, these growths begin to grow becoming flowers and eventually embryo clusters of grapes.  

Canes

From veraison onward, through harvest and after, shoots begin to harden (“lignify”). After the leaves have fallen from the vine, these shoots are called canes. During the winter when the vine is dormant, the canes are pruned in a number of different ways for the next season’s growth. When canes have one to four buds, they are called spurs or fruiting spurs.

In choosing a grape, the vineyardist has two choices, to use either a clonal selection or mass selection which is often called “selection massale.” Clones are genetic copies of a single vine, selected for its disease resistance, potential yield, or aroma and flavor profile. Specific clones can be purchased from a nursery where the plant material has been quarantined and treated for viruses. However, so-called “suitcase clones” are also sometimes brought into the country illegally. Otherwise, mass selection is defined by taking budwood from a number of existing vines in a vineyard vs. using a single clone. Using a broader diversity of budwood results in the best traits being retained and negative ones avoided. 

The cambium is the single layer of cells just below the bark. The more cambium contact between the scion (cutting of budwood) and rootstock the better the chances for success in the graft. Grafting is also a time-consuming, labor-intensive process that must be done by hand. The scions used for grating must be healthy and disease-free. 

Once grafted, vines take at least three years to bear a crop of fruit that can be used for winemaking. At six years vines are considered mature enough to bear fruit and withstand various environmental stresses. After 20 years the vines of many classic grape varieties will start to decline and need to be replaced. There are notable exceptions such as Syrah and Zinfandel which can age far longer.  

In the last 20 years advancements in designing vineyards, trellising systems, and canopy management have led to considerable improvements in the overall quality of grapes and wine in California. Before then a standard trellising system was used throughout the state without much consideration of the specific climate, soil type, variety, and rootstock. Here are the most common trellising systems used in California. 

Bush or Goblet 

*Insert image of bush trained vines. 

Many of the early vineyards planted in California used a “bush” or Goblet system of trellising, where the vine is free-standing and secured to a stake. The French term “Gobelet” translates as goblet, and refers to the shape of the vine—a trunk with eight or more spurs. The Goblet system was and remains especially effective in warmer, drier areas where sunburn could be a potential issue for the fruit during the growing season and dry conditions result in less incidence of fungus and rot. Vineyards planted to Syrah and other Rhône varieties and Zinfandel were traditionally planted using the bush or Goblet system. Some vineyards planted using bush or Goblet are over a century old. 

Vertical Shoot Positioning (VSP)

*Insert image of VSP vineyard

Vertical Shoot Positioning is one of the most widely used trellising systems for quality vineyards in coastal regions with low to medium vigor. In VSP the vine shoots are trained upwards on several wires, with the fruit zone just below, about three feet (1 m) off the ground. Though more expensive to install and maintain, the VSP system helps with canopy management techniques such as leaf removal, shoot removal, and green harvesting, while also making it easier to achieve even fruit ripeness. VSP is also optimal for vineyards that are mechanically harvested.

California Sprawl 

*Insert image of California Sprawl vineyard

California Sprawl is a simple single curtain trellising system consisting of a single cordon wire and just one foliage wire above it. The system promotes vigorous—sprawling—vine growth; hence the name. While it is relatively inexpensive to install and maintain, the system is not conducive to even ripening because of the shaded canopy. It is also more prone to mold/mildew during a wet growing season. California sprawl is widely used in high-yielding vineyard areas. 

Scott Henry System

*Insert photo of the Scott Henry System

The Scott Henry system is used in coastal vineyards where the expected vigor is too high to use VSP and narrow row spacing is required. In the Scott Henry system two fruit zones are created by training spurs on sets of two upper and two lower training wires. The system is relatively inexpensive to install and maintain.

Richard Smart System

*Insert photo of the Richard Smart System

Australian Richard Smart is widely considered one of the most influential viticulturists in the last two-plus decades. His  work on canopy management techniques has revolutionized grape growing internationally. Smart’s trellising system is a variation of the Scott Henry system, except that spurs on cordons are alternatively trained up and down, creating two canopies and two fruit zones.

Sustainable farming

Includes organic or biodynamic farming practices. Examples of sustainable practices include using sheep and certain species of birds to control weeds and pests, planting cover crops to control erosion and insect pests, and installing drip irrigation systems and collection ponds to conserve water. Other practices include composting and recycling to minimize waste. 

Organic Farming

Vineyards that are farmed organically must follow guidelines set up by the National Organic Program (NOP). These include the mandated use of NOP-approved materials including natural fertilizers and pest controls. The country’s largest organic certification organization is the CCOF, or California Certified Organic Farmer.

Biodynamic farming

Is an elevated form of sustainable farming based on principles set out by Rudolf Steiner in 1924. Biodynamics takes lunar forces and tides into consideration in farming. For example, planting and pruning are done according to the phases of the moon. Further, the farm is seen as a single, closed entity. In biodynamic farming no artificial pesticides or fungicides are used. There are eight biodynamic treatments used in the vineyard, made of organic materials from the estate. These treatments are used to improve and maintain the health of the microbiome in the soil. In California, wineries and vineyards are certified by the international organization called the Demeter Biodynamic Trade Association. It should also be noted that the practice of biodynamics is still considered controversial by some in the industry.

Powdery Mildew (Oidium)

Though native to North America, powdery mildew spread on a global scale. It thrives in humid  and wet conditions. Powdery mildew infects all green parts of the plant with a dusty white powdery substance. If a vine is infected before flowering the yields will be reduced. Vine infection after fruit set will result in smaller berries that never reach full size. The fungus is controlled by applications of sulfur and other fungicides.

Downy Mildew (Peronospora)

In the 1880s downy mildew was transported to Europe on native American vines and quickly spread through France and the rest of the continent. The fungus infects all green portions of the vine, inhibiting photosynthesis. Over time a white fuzzy growth forms on the underside of the leaves. Bordeaux Mixture, a solution of copper sulfate, water and lime, was developed to prevent outbreaks of downy mildew.

Pierce’s Disease (Xylella Fastidiosa)

Is a disease spread by the blue-green sharpshooter. As the insects feed on the vines, they inject the disease into the vine which quickly spreads throughout the plant. There is no cure for Pierce’s Disease as of now.  Current control is through the use of parasitic wasps that prey on the eggs of the sharpshooters.

Phylloxera (Daktulosphaira Vitifoliae)

Phylloxera is a tiny louse that feeds on roots and leaves, creating fungal infections which block the flow of water and nutrients to the vine. At present there is no cure for phylloxera. However, grafting vinifera budwood on to non-vinifera rootstock has historically proven to be the most successful remedy

Grey Mold

Is a form of botrytis that can infect leaves and/or berries at any time of the year when wet conditions occur and temperatures range between 60 and 75°F (15.5-24°C). Initially spots appear on the leaves, which soon turn brown and start to rot. With grapes, infection covers the berries with mold and decay. 

Black Rot (Guignardia Bidwellii)

Is another fungal disease native to North America. Black Rot was transported to Europe in the 1880s with the importation of native rootstock to combat phylloxera. It appears as black spots on shoots, leaves, and berries. If untreated yields can be considerably reduced. However, vines can be treated with fungicides. 

Esca (Black Measles)

Is a fungal vine trunk disease. Infected vines initially show discoloration with the leaves eventually shriveling in the middle of the season and dropping off. Infected grapes do likewise, with the vine suddenly dying within days of infection. Esca is a problem worldwide, especially in warmer climates. There is no known cure or treatment.   

Eutypa Dieback

Or Eutypa lata, is one of the most destructive fungal diseases. It initially appears on a single spur before spreading to the rest of the vine. Eutypa stunts the growth in shoots and leaves and shrivels the grapes. There is no known cure or treatment.