Grapevine refers to the plant that belongs to the genus Vitis of the family Vitaceae. In total, there are about 60 species of Vitis, of which the most commonly grown is Vitis vinifera. Grapevine is either deciduous or evergreen. The leaves are palmately-lobed and arranged alternately. The fruit of this species is a true berry, known as grapes. Cultivated varieties of grapevine bear green, red, or purple colored grapes. In the wild version of these grapes, the berries are small and dark purple in color. Grapevine grows best in humid climatic conditions.
Its life cycle can be categorized under certain stages, depending upon their growth pattern. In fact, caring for the grapevine depends on the season and growth of the plants. Understanding their annual life cycle is necessary so as to take care of the plants for maximum harvest. It begins after the dormant stage, during early spring.
Sap concentration occurs after the plants have been pruned in dormancy, which is necessary for the development of buds. The newly developed buds are prone to frost damage, hence proper protection is necessary. Depending on the environmental conditions, new leaves develop within 3-4 weeks after the bud break in March. At this time, maximum food storage is done through photosynthesis.
Examine the onset of powdery mildew disease on the leaves and stems. If necessary, apply anti-fungal sprays to control it. In case if there is an extra shoot growth, remove by suckering without affecting the vine. This allows storage of maximum energy for the formation of flower clusters.
Development of flower clusters usually occurs within 9-10 weeks after the bud break, in late May or early June. Flowering time may vary based on the vitis variety and climatic conditions of the region. Pollination of flowers is necessary for the formation of berries. Heavy rain or too hot temperature conditions may prevent pollination. Within a week or two, the flowers are pollinated, thus resulting in the development of small berries.
The fertilized or pollinated flowers develop into small berries, while those that are unfertilized, drop. Young grape berries should be protected from frosting. The plants should be watered heavily to prevent drying out of the berries. In this stage, the cells undergo division leading to enlargement of the berries. Thinning of the leaves and shoots should be done in order to give space to the berries. While doing so, insure that the fruits are not exposed directly to sun, as it may cause sun scald.
This stage is characterized by softening and color development of berries and can be considered as the ripening stage. Berry softening is due to the accumulation of sugars. The berry color depends on the variety of the grapevine. For better coloration of the berries, many growers prefer to trim the canopy. Veraison usually occurs in late July, about 45 days after fruit set.
Maturity of the berries varies depending on the variety of the vine. Traditionally, the maturity period is considered 100 days after the flower development. Harvesting is done after testing the acid and sugar level of the berries.
The life cycle is completed in fall after harvesting the fruits, when the plants are in dormant stage. During dormancy, the vine leaves turn yellow and fall. Proper pruning in this stage is necessary, so as to protect the grapevine from extreme frost. It will also help in storing maximum energy for developing leaves and bearing fruits.