Grape vines have been cultivated for thousands of years. Grapes can be eaten raw, dried and stored as raisins, or fermented as wine, and grape leaves are a part of many cuisines. Viticulturists have developed a variety of methods for growing grapes intended to produce wine, but home gardeners grow grape vines as well.
The roots of a grape vine are multi-branched structures that reach that reach about 3 feet into the soil and anchor the vine securely. Old roots are woody, and new growth is both lateral and vertical. Lateral roots develop many delicate root shoots. Roots absorb water and nutrients from the soil, store carbohydrates and produce the hormones that regulate vine growth. They have a mutually beneficial relationship with specific soil fungi called mycorrhizae. The presence of mycorrhizae in the soil is necessary for the health and growth of the grape vine.
Graft and Trunk
Although some grape vines are grown on their own roots, viticulturists typically graft a variety of grape onto a different variety of roots. The grafted variety is called a scion, and the root variety is the rootstock. This practice allows grapes that have specific desirable characteristics for making wine to be grown on sturdier roots, often chosen specifically for resistance to particular diseases or pests. The graft union is just above ground level. Shoots grow upward from the roots or the graft union. Viticulturists select one and remove the others, and the single shoot develops into a sturdy trunk over several years. The top of the trunk is called the head. Depending on how the vine is pruned, short sturdy arms or longer cordons, trained to grow horizontally, grow from the head.
Shoots, the green stems which develop from primary buds, are the primary growth structure of grape vines. Tendrils, leaves, flower clusters that will mature into fruits, and more buds are arranged in regular patterns along the shoot. The shoot grows longer from the shoot tip, which never forms a terminal bud. Canopy is the collective term used to describe the shoots, leaves and fruit of grape vines. Canes are essentially mature shoots that have developed a woody structure. When they drop their leaves during the dormant season, viticulturists prune them to retain only some of the buds and direct new growth. When canes are pruned so short that they hold only one to four buds, they are called spurs.
Leaves and Tendrils
The broad part of a leaf is a blade, and the small stalk-like portion that connects it to the shoot is the petiole. Photosynthesis occurs in the blade portion of the leaf. Grape leaves are edible. Tendrils are small green structures that coil around nearby objects, giving support to the growing shoot. They grow from a point opposite the leaf, but not every leaf is paired with a tendril.
Flowers and Grapes
Flower clusters grow opposite leaves along the shoot. Most shoots develop one to three flower clusters; the name depends on the variety of grape vine and growing conditions when the bud was formed. Each cluster may contain only a few or up to several hundred flowers; the number depends on the variety. When fertilized, the flower clusters develop into clusters of grapes.