Grape cultivation is an exciting idea to establish a new orchard. Grape cultivation is a rewarding venture for beginners, offering the opportunity to grow one of the most versatile and globally valued fruits. Grapes thrive in a variety of climates, and with proper knowledge of soil preparation, planting, pruning, and pest management, beginners can achieve high yields and quality produce. Whether for table consumption, wine production, or raisins, understanding the essentials of grape cultivation sets the foundation for a thriving and sustainable vineyard. This guide covers details about grape cultivation.
Taxonomy
Vitis has two subgenera
Muscadinia
Commonly known as muscadine grapes, this subgenus is characterized by small fruit clusters or fruits borne singly. The grapes have thick skin, and the berries typically detach individually as they mature. Key species in this subgenus include Vitis rotundifolia, the primary cultivated species, and Vitis munsoniana, also known as the bird grape, which grows wild.
rotundifolia
Vitis rotundifolia, commonly known as the muscadine grape, is primarily cultivated for fresh fruit but also valued for producing juice and sweet wines, particularly in the southern United States. This grape variety is known for its extreme vigor and remarkable tolerance to diseases, making it well-suited for diverse growing conditions.
Euvitis
The subgenus Euvitis, commonly referred to as the true grape, is characterized by its elongated clusters of fruit, earning it the name “bunched grape.” This group includes important species such as Vitis vinifera, widely used in winemaking, and Vitis labrusca, known for table and juice grapes.
labrusca
Vitis labrusca, commonly known as the Concord grape, is often referred to as the American bunch or fox grape. It is primarily used for producing sweet juice, various grape-derived products, and sweet wines. The main cultivar, Concord, features dark blue fruit and accounts for approximately 80% of the total production of this species.
vinifera
Vitis vinifera, commonly known as the European or wine grape, is often referred to as the “Old World grape.” Most of its production is centered in Europe, where it plays a vital role in winemaking. This species, along with related hybrids, accounts for over 90% of the world’s grape production, underscoring its global importance in the grape industry.
French American hybrids, developed from crosses between Vitis vinifera and Vitis labrusca, are known for their resistance to phylloxera, a destructive vineyard pest. Grapes are also classified based on their use into four main categories: table grapes for fresh consumption, raisin grapes for dried fruit, sweet juice grapes for beverages, and wine grapes for winemaking.
Origin
The origin of grape species varies by type: Vitis vinifera is native to regions near the Caspian Sea. Vitis labrusca grows wild from Maine to the South Carolina Piedmont, extending west to the Tennessee mountains. Meanwhile, Vitis rotundifolia is indigenous to areas from Virginia through central Florida and as far west as eastern Texas.
Climate
Grapes thrive in temperate to subtropical climates, requiring a long growing season with high summer temperatures and mild winters. An ideal ripening season should be free from rainfall to ensure fruit quality. These conditions are characteristic of Mediterranean climates. The optimal summer temperature for grape cultivation ranges between 10°C and 20°C.
Chilling requirement
The chilling requirement for grape cultivation varies significantly among species. Concord grapes generally have a high chilling requirement, ranging from 1,000 to 1,400 hours. In contrast, Vitis vinifera varieties require significantly less chilling, typically between 100 and 500 hours. Muscadine grapes fall in the intermediate range. Some grape varieties are adaptable and can even be cultivated in tropical regions.
Cold hardiness
Cold hardiness is a critical factor limiting the cultivation of Vitis vinifera grapes, as primary bud damage occurs at temperatures between -18°C and -23°C, and trunk injury or death may occur below -23°C. Vitis labrusca grapes exhibit greater cold resistance compared to Vitis vinifera or French-American hybrids, tolerating temperatures as low as -23°C to -29°C. Muscadine grapes, however, are the least cold-hardy, suffering fatal damage at temperatures below -18°C.
Soil for grape cultivation
Grapes and their rootstocks can thrive in a wide range of soil conditions, from high pH and saline soils to acidic and clayey types. However, the ideal soils for grape cultivation are deep, well-drained, and of light texture. Highly fertile soils are generally unsuitable, as they can lead to excessive vigor and uncontrolled yields, which are undesirable for optimal grape production.
Fertilizers for grape cultivation
As a perennial crop, grapevines are nourished with organic fertilizers to provide a consistent source of organic carbon, enhance soil organic matter, and support beneficial soil microorganisms. Worldwide, fertilizers with various NPK ratios and essential micronutrients are utilized to improve grape yield and quality. A combination of mineral and organic fertilizers has been found to deliver the most effective results, ensuring higher productivity and desirable grape characteristics.
Irrigation
Drip irrigation, when effectively managed, offers exceptional water efficiency by minimizing deep percolation below the root zone and reducing surface evaporation and runoff. This method targets a specific area of the root zone, ensuring water reaches the roots where it is most needed.
Nutrient delivery through drip irrigation is highly efficient, as fertilizers are applied directly to the concentrated root zone. This method allows for easy and frequent fertilization, supporting optimal nutrient uptake and maintaining high soil-water matrix potentials with well-scheduled irrigation.
Related Article: Strawberry Cultivation Guide.
Botany
Plant
The grapevine is a woody, climbing plant classified as a liana, known for its ability to attach and grow on supporting structures.
Leaves
The leaves of grapevines are arranged alternately along the stem. The muscadine grape has small, round, unlobed leaves, typically 2-3 inches in size, with a dentate margin. In contrast, the leaves of vinifera and labrusca varieties are larger, ranging from 8-10 inches, and are typically cordate to orbicular in shape with deep lobes. Tendrils are found opposite the leaves at the nodes.
Inflorescence
The inflorescences of grapevines are racemose or panicle-shaped and are borne on the current season’s growth. Euvitis varieties can have more than 100 flowers per inflorescence or cluster, while muscadine grapes typically have only 10-30 flowers per cluster.
Flower
The flowers of grapevines are small, about 1/8 inch in size, and are green in color. There are three types of flowers: female, male, and hermaphrodite. Vinifera and labrusca varieties produce perfect (hermaphrodite) flowers, making them self-fruitful. Some muscadine grapes, however, only have pistillate (female) flowers. Each flower bear five sepals, five petals, and five stamens. The ovary is superior, with two locules, each containing two ovules. The sepals are fused, forming a calyptra or cap, in which the petals are also fused.
Fruit
The fruit of grapevines is a true berry, with the ovary containing two locules, each holding two seeds. Muscadine grapes are characterized by their thick skin.
Pollination
Most grape varieties are self-pollinating and self-fruitful, meaning they do not require a separate pollinizer to produce fruit. However, certain Muscadine grape varieties are not self-fruitful and need to be interplanted with cultivars that have perfect flowers to ensure proper pollination.
Parthenocarpy
Parthenocarpy does not occur in grapes; all grape varieties require pollination for fruit set, including seedless cultivars. In seedless varieties, fertilization still takes place, but the embryos abort shortly afterward, a process known as stenospermocarpy.
Fruit growth and development
The period from bloom to fruit maturity in grapes ranges from approximately 150 to over 200 days. This duration varies depending on the grape species, cultivar, and climatic conditions.
Commercial cultivars
Table grapes
Table grapes primarily consist of seedless cultivars from the Vitis vinifera species. Popular white varieties include Thompson Seedless (also known as Sultanina or Sultana) and Perlette. For red varieties, major cultivars include Flame Seedless, Crimson Seedless, and Ruby Seedless.
Seeded cultivars
Seeded grape cultivars include the Emperor, Ribier, and Calmeria, which are commonly grown in the USA. In Italy, a popular white variety is Italia, while in Spain, the white Almeria grape is widely cultivated.
Propagation
Root stocks
Phylloxera was introduced to Europe from eastern North America, posing a significant threat to vineyards. To combat this pest, researchers sought grape species resistant to Phylloxera in its native range.
Two species, Vitis riparia (Riparia Gloire) and Vitis rupestris (Rupestris St. George), were identified for their resistance to Phylloxera. However, these species have low tolerance for high pH soils.
In Texas, Vitis berlandieri was found to be resistant to Phylloxera and tolerant of high pH soils. Despite these advantages, it presents challenges as it is difficult to propagate from cuttings.
To address this, hybrids of Vitis berlandieri were developed, which are easier to root. Most rootstocks used today are clonal selections derived from hybrids of V. riparia, V. rupestris, V. berlandieri, and other American grape species.
Propagation method
The most common propagation method for grapes is bench grafting. Additionally, rooted cuttings, T-budding, and, to a limited extent, tissue culture are used depending on the situation.
Scion and Rootstock Collection
Dormant scion and rootstock canes are typically collected in late winter or early spring. Alternatively, they can be harvested in late fall and stored under refrigeration for 1 to 2 months. Rootstock canes are usually taken from mature hardwood.
Graft Preparation
For grafting, canes are cut into 12 to 14 inches, ensuring the scion and rootstock are of the same diameter. Whip-and-tongue grafts are commonly used. To prevent dehydration, the scion is waxed, and moist peat moss is packed around the rootstock. The grafts are then stored for 3-4 weeks at 80°F in a specialized room before being planted in the nursery.
Training and Pruning
Training and pruning are crucial aspects of grape production. Vines need to be shaped and sized according to specific training systems. Since fruit develops on new canes, proper pruning ensures healthy growth. Maintaining a balance between fruit production and vegetative growth is essential for optimal yield and vine health.
Training system
Two basic forms are used
Head system
The head training system in grape cultivation involves growing the vine as a central trunk with short, stubby arms extending outward. These arms support a few canes or spurs. This simple, compact structure is suitable for smaller vineyards, requiring minimal support and is ideal for low-vigor sites or certain grape varieties.
Cordon system
The cordon training system features a horizontal main cordon arm that extends in one or both directions.
Pruning
Grapevines require pruning during two key periods: summer and winter. Summer pruning focuses on managing the current season’s growth, while winter pruning, also known as dormant pruning, regulates growth from the preceding season.
Types of Pruning
Grapevines are pruned in two ways:
Cane pruning
Cane pruning involves cutting back older canes.
Spur pruning
Spur pruning trims shoots from the previous year.
Pruning Practices by Varieties
The choice of pruning method depends on the species and cultivar. European grapes can be pruned either by the cane or spur method, while American varieties and many hybrids typically undergo spur pruning.
Fruit maturity
Fruit Maturity Indicators
Grapes exhibit specific indicators of maturity, which include the berry’s color and size, as well as the color of the cluster stem, which changes to pale green or straw color as the fruit ripens. Additionally, key chemical parameters such as °Brix (sugar content), acidity, and pH vary depending on the intended use of the grapes.
Maturity Standards for Different Uses
- Raisin Grapes: Optimal sugar content ranges from 22 to 23°Brix.
- White Wine Grapes: Harvested at 19 to 23°Brix, with a pH below 3.3 and acidity over 0.7%.
- Red Wine Grapes: Typically mature at 20.5 to 23.5°Brix, with a pH below 3.4 and acidity above 0.65%.
Harvesting
Grapes are harvested using either hand or mechanical methods, depending on their intended purpose. Hand harvesting is commonly used for table grapes and high-quality wine grapes, as this method minimizes damage and ensures careful handling. On the other hand, mechanical harvesting is preferred for grapes destined for raisins, wine, juice, and other processed products.
Mechanical harvesters are equipped with horizontally pivoting arms or vibrating fingers designed to strike the canopy gently, effectively dislodging clusters or berries without significant damage. This method is efficient for large-scale operations and reduces labor costs.
Storage of Grapes
vinifera Grapes
Grapes from V. vinifera varieties are well-suited for long-term storage. They can be kept for 3 to 6 months at a temperature of approximately 0°C and a relative humidity (RH) of 95%, ensuring their quality and freshness.
labrusca Grapes
V. labrusca grapes are more perishable and can only be stored for 2 to 8 weeks under similar conditions of 0°C and 95% RH. Their shorter storage life makes them less ideal for prolonged storage.
Muscadine Grapes
Muscadine grapes, known for their distinct characteristics, can be stored for up to 3 weeks at 0°C and a slightly lower RH of 90%, ensuring optimal preservation during this period.
Major Pest
Phylloxera
Grape phylloxera (Dactylosphaera vitifolii), also known as root louse, is an aphid species and one of the most destructive pests of grapevines, particularly where resistant rootstocks are unavailable. Originating from American grapes, this pest has a severe impact on susceptible vines.
Leaf Damage
Phylloxera causes the formation of galls on leaves. These galls, approximately the size of half a pea, cover the entire leaf surface and are open on the underside. Within the galls are eggs and wingless yellowish aphids. This infestation results in leaf distortion, necrosis, and premature defoliation, severely affecting vine health.
Nymph Activity
During summer, nymphs hatch and feed on leaves, causing the formation of small galls. These nymphs eventually drop to the soil, burrowing into the ground where they attack the roots. Feeding on roots leads to the formation of root galls, known as nodosities and tuberosities, which compromise the root system and ultimately destroy it.
Spread and Control Challenges
As the season progresses, winged forms of phylloxera emerge and fly to other vines, leading to rapid spread. Their mobility and destructive nature make phylloxera extremely difficult to control, requiring diligent vineyard management and the use of resistant rootstocks for effective mitigation.
Diseases
Powdery Mildew
Pathogen: Uncinula necator
Overview
Powdery mildew is a serious disease affecting grapevines and is prevalent in all grape-producing regions. It primarily targets all green tissues of the plant, including the fruits, significantly impacting yield and vine vigor.
Symptoms
The disease manifests as powdery-looking hyphae covering the leaves, with other infected plant tissues also displaying a whitish powdery appearance. Fruits infected with powdery mildew contribute to off flavors in wine, compromising quality and marketability.
Disease Cycle
The fungus overwinters within the buds and infects emerging tissues, covering both the upper and lower surfaces of leaves as the growing season begins.
Environmental Influence
Powdery mildew thrives in drier climates where the absence of rainfall aids its sporulation and spread. However, rainfall disrupts its lifecycle by washing away conidia, preventing sporulation, and disturbing hyphae, thereby reducing disease severity.
Botrytis Bunch Rot (Noble Rot)
Pathogen: Botrytis cinerea
Overview
Botrytis bunch rot is a significant disease of grapevines, affecting multiple parts of the plant including buds, young shoots, inflorescences, and fruits. It is particularly problematic in regions with high humidity and cool climates near harvest time.
Symptoms
Infected buds and shoots turn brown and desiccate, while infected berries develop off-colors and may be covered with brown or white mycelia. Postharvest losses in table grapes are also commonly attributed to this disease.
Susceptibility
Grape cultivars with tight clusters and thin-skinned fruits are more prone to Botrytis infection, making variety selection a key factor in disease management.
Control Measures
Improving canopy ventilation can enhance airflow, lower relative humidity, and reduce disease incidence. Proper vineyard management practices play a crucial role in mitigating Botrytis bunch rot.
