The Life Cycle of a Grape
One Year in the Vineyard
Winter Dormancy
December-March (Jun-Sep)
Sleeping vines at the Moselle (Mosel, Germany) in February.
Dormancy is a stage with no growth activity. The vine rests from autumn (leaf fall) to spring (bud burst).
The drop in temperatures triggers the dormancy. The vine stores its nutrients (carbohydrates) in the cordon, trunk, and roots, and the vine loses water (dehydrates) to avoid winter frost damages.
At this stage, the leaves fall off, and the soft shoots get woody and turns into next year new canes.
Winter Pruning
December-March (Jun-Sep)
Winter pruning is a selective removal of 70-90% of the branches and buds.
The first round of winter pruning removes the majority of the canes (70-90%) to allow a more precise bud selection at a later pruning.
Fruit is produced only on shoots from one year old branches, so the goal of the pruning is to maximize their amount. Pruning also assures maximum energy and nutrients to the fully ripen grapes.
Bud Break (Budding - Budburst)
March-April (Sep-Oct)
Budding is the first sign of life.
Budding is the first sign of life. The vine is weaking up and needs to produce leaves to generate carbohydrates (via photosynthesis) to fuel the new growth.
Bud Break happens when daily temperatures reach 10 °C (50 °F). The vine enters a new growing season trained to a particular system and pruned to a certain number of buds.
As temperature and light increase, starches (stored carbyhydrates) are converted into sugar, and fluid begins to move in the vine. As the activity accelerates, branches can grow 5-15 cm each day, and buds swell and generate new shoots.
Flowering
April-May (Oct-Nov)
Flowering can last one or two days in a warm and dry climate, or one month in a cool and wet climate.
Grapevine flowers bloom in a cluster 6 to 9 weeks after bud break. Flowering depends on warmer temperature and stronger sunlight: a daily temperature of 15-20 °C (59–68 °F) activates the process.
Domesticated Vitis Vinifera varietals are hermaphroditic: the blossoms self-pollinate, without help from bees, because flowers are bisexual (have both sexes).
Pollen from a male flower (stamen) fertilizes the female flower (ovary), and a seed (embryo) develops. The entire ovary grows to become the grape berry itself with seeds contained within.
Fruit Set
May-June (Nov-Dec)
Small green peppercorn-sized berries grow bigger and harder, high in acid and low in sugar.
Fruit set is the stage immediately after flowering.
As temperature rises, the growth accelerates, shoots expand and the vine starts to produce new nutrients via photosynthesis. There are hundreds of flowers in a grape inflorescence (the group of flowers on a stem). However, a relatively low percentage of these flowers will form a grape.
Ripening (Véraison)
July-September (Jan-Mar)
Grapes start green, then they turn yellow or pink, (white grapes) or red, blue, purple or black
Ripening happends in July/August (South: Jan/Feb).
It is the stage where the grapes begin to change color.
This is a signal of fruit maturation (ripening), berries begin to soften, acid level falls and sugar level rises.
The balance between sugars and acids is the most critical aspect to determine the quality of the wine. The longer the grape is on the vine, the higher the sugar and the lower the acidity will be.
Veraison is uneven (different degrees of ripeness) and the berries exposed to more sun and light get a head start.
Harvesting
September-October (March-April)
Hand picking Gruner Veltliner grapes at Hahndorf Hill vineyard in the Adelaide Hills
The enologist chooses when to harvest, usually between September-October (South: March-April).
If you pick too early, the tannins are green and bitter. If you pick too late, the sugar level kills the acidity.
Generally, harvesting takes from one week to a month of hard labor. Once you start, you can't stop. The main factors are maturity (skin thickness, berry texture, seed and stem color), optimal PH, sugar and acidity levels, optimal ripeness, wine style, weather forecasts, etc.
Sparkling wines need high acidity, so the harvest is early. Dessert wines need high sugar, so the harvest is late. White grapes mature sooner and are normally harvested before black grapes that need more time to achieve the ideal color and sugar-acid balance.
Canopy Management
All Year Round
Canopy managment is about designing the architecture of a grapevine.
Canopy refers to leaves, shoots and fruit.
Canopy managment is about designing the architecture of a grapevine, to guide its energy into the ultimate result of perfectly mature fruit.
Canopy Management Benefits
- Optimize the yield
- Improve the fruit quality
- Improve the sunlight exposure
- Provide good air circulation
- Reduce the risk of diseases
Canopy Management Methods
- Trellising
- Pruning
- Cluster Thinning
- Shoot positioning
- Leaf Removal
