![Grapes02](https://upload.wikimedia.org/wikipedia/commons/e/ec/Grapes02.jpg)
The annual growth cycle of grapevines is the process that takes place in the vineyard each year, beginning with
bud break in the spring and culminating in
leaf fall in autumn followed by winter
dormancy
Dormancy is a period in an organism's life cycle when growth, development, and (in animals) physical activity are temporarily stopped. This minimizes metabolic activity and therefore helps an organism to conserve energy. Dormancy tends to be clo ...
. From a
winemaking
Winemaking or vinification is the production of wine, starting with the selection of the fruit, its fermentation into alcohol, and the bottling of the finished liquid. The history of wine-making stretches over millennia. The science of wine and ...
perspective, each step in the process plays a vital role in the development of
grape
A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters.
The cultivation of grapes began perhaps 8,000 years ago, ...
s with ideal characteristics for making
wine
Wine is an alcoholic drink typically made from fermented grapes. Yeast consumes the sugar in the grapes and converts it to ethanol and carbon dioxide, releasing heat in the process. Different varieties of grapes and strains of yeasts are m ...
.
Viticulturalists and vineyard managers monitor the effect of climate,
vine disease
This is a list of diseases of grapes (''Vitis'' spp.).
Bacterial diseases
Fungal diseases
Miscellaneous diseases and disorders
Nematodes, parasitic
Phytoplasma, virus and viruslike diseases
See also
*'' Ampeloglypter ater''
*'' Am ...
and pests in facilitating or impeding the
vine's progression from bud break,
flowering,
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
set,
veraison,
harvesting, leaf fall and dormancy-reacting if need be with the use of viticultural practices like
canopy management,
irrigation
Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow Crop, crops, Landscape plant, landscape plants, and Lawn, lawns. Irrigation has been a key aspect of agriculture for over 5,00 ...
,
vine training and the use of
agrochemicals. The stages of the annual growth cycle usually become observable within the first year of a vine's life. The amount of time spent at each stage of the growth cycle depends on a number of factors-most notably the type of climate (warm or cool) and the characteristics of the
grape variety
This list of grape varieties includes cultivated grapes, whether used for wine, or eating as a table grape, fresh or dried (raisin, currant, sultana). For a complete list of all grape species including those unimportant to agriculture, see Viti ...
.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 741–742 Oxford University Press 2006 ]
Bud break
![Regent Grape Vine with bud](https://upload.wikimedia.org/wikipedia/commons/1/1a/Regent_Grape_Vine_with_bud.jpg)
The grape starts its annual growth cycle in the spring with bud break. In the Northern Hemisphere, this stage begins around March while in the
Southern Hemisphere it begins around September when daily temperatures begin to surpass 10 °C (50 °F). If the vine had been
pruned
Pruning is a horticultural, arboricultural, and silvicultural practice involving the selective removal of certain parts of a plant, such as branches, buds, or roots.
The practice entails the ''targeted'' removal of diseased, damaged, dead, ...
during the winter, the start of this cycle is signaled by a "bleeding" of the vine. This bleeding occurs when the soil begins to warm and
osmotic
Osmosis (, ) is the spontaneous net movement or diffusion of solvent molecules through a selectively-permeable membrane from a region of high water potential (region of lower solute concentration) to a region of low water potential (region of ...
forces pushes water, containing a low concentration of
organic acid
An organic acid is an organic compound with acidic properties. The most common organic acids are the carboxylic acids, whose acidity is associated with their carboxyl group –COOH. Sulfonic acids, containing the group –SO2OH, are rel ...
s,
hormones
A hormone (from the Ancient Greek, Greek participle , "setting in motion") is a class of cell signaling, signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and beh ...
,
mineral
In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...
s and sugars, up from the
root system of the vine and it is expelled from the cuts (or "wounds") left over from pruning the vine. During this period a single vine can "bleed" up to of water.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 82 Oxford University Press 2006 ]
Tiny buds on the vine start to swell and eventually
shoots begin to grow from the buds. Buds are the small part of the vine that rest between the vine's
stem
Stem or STEM may refer to:
Plant structures
* Plant stem, a plant's aboveground axis, made of vascular tissue, off which leaves and flowers hang
* Stipe (botany), a stalk to support some other structure
* Stipe (mycology), the stem of a mushro ...
and the
petiole (leaf stem). Inside the buds contain usually three primordial shoots. These buds appear in the summer of previous growth cycle green and covered in scales. During winter dormancy they turn brown until the spring when the vine begins the process of bud break and the first sign of green in the vineyard emerges in the form of tiny shoots.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 107 Oxford University Press 2006 ] The energy to facilitate this growth comes from reserves of
carbohydrate
In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may or ma ...
stored in roots and wood of the vine from the last growth cycle. Eventually the shoots sprout tiny leaves that can begin the process of
photosynthesis
Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...
, producing the energy to accelerate growth. In warm climates, after about 4 weeks the growth of the shoots starts to rapidly accelerate with the shoots growing in length an average of 3 cm (1 in) a day.
In
temperate climate
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
s, where temperatures can reach above 10 °C (50 °F) in mid-winter, some early budding varieties (such as
Chardonnay
Chardonnay (, , ) is a green-skinned grape variety used in the production of white wine. The variety originated in the Burgundy wine region of eastern French wine, France, but is now grown wherever wine is produced, from English wine, Englan ...
) can be at risk of premature bud break. This is a potential viticultural hazard in places like the
Margaret River region of Western Australia where warm currents from the Indian Ocean can coax Chardonnay vines to prematurely bud in the mid-winter month of July. After bud break, the young shoots are very vulnerable to
frost
Frost is a thin layer of ice on a solid surface, which forms from water vapor in an above-freezing atmosphere coming in contact with a solid surface whose temperature is below freezing, and resulting in a phase change from water vapor (a gas) ...
damage with vineyard managers going to great lengths protect the fragile shoots should temperature dramatically drop below freezing. This can include setting up heaters or wind circulators in the vineyard to keep cold air from settling on the vines.
Flowering
![Vigne inflorescence 2](https://upload.wikimedia.org/wikipedia/commons/1/1a/Vigne_inflorescence_2.jpg)
Depending on temperatures, 40–80 days after bud break the process of flowering begins with small flower clusters resembling buttons appearing on the tips of the young shoots. Flowering occurs when average daily temperatures stay between 15–20 °C (59–68 °F) which in the Northern Hemisphere wine regions is generally around May and for the Southern Hemisphere regions around November. A few weeks after the initial clusters appear, the flowers start to grow in size with individual flowers becoming observable.
It is during this stage of flowering that the
pollination
Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds ...
and
fertilization
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...
of the grapevine takes place with the resulting product being a grape berry, containing 1–4
seeds
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiosperm pl ...
.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 276 Oxford University Press 2006 ]
![Vitis vinifera fleur 1](https://upload.wikimedia.org/wikipedia/commons/d/d2/Vitis_vinifera_fleur_1.jpg)
Most cultivated ''
Vitis vinifera
''Vitis vinifera'', the common grape vine, is a species of flowering plant, native to the Mediterranean region, Central Europe, and southwestern Asia, from Morocco and Portugal north to southern Germany and east to northern Iran. There are curre ...
'' grape vines are
hermaphroditic, with both male
stamen
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filame ...
s and female
ovaries
The ovary is an organ in the female reproductive system that produces an ovum. When released, this travels down the fallopian tube into the uterus, where it may become fertilized by a sperm. There is an ovary () found on each side of the body. T ...
, while many wild grapes are either male, producing pollen but no fruit, or female, producing fruit only if a pollinator is nearby.
Hermaphroditic vines are preferred for cultivation because each vine is more likely to
self-pollinate
Self-pollination is a form of pollination in which pollen from the same plant arrives at the stigma of a flower (in flowering plants) or at the ovule (in gymnosperms). There are two types of self-pollination: in autogamy, pollen is transferred t ...
and produce fruit.
At the beginning of the flowering process the only part that is visible is the fused cap of petals known as the
calyptra. Shortly after the calyptra is shed, liberating the
pollen
Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gametophyt ...
from the
anther
The stamen (plural ''stamina'' or ''stamens'') is the pollen-producing reproductive organ of a flower. Collectively the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filam ...
s of the stamen. Wind and insects generally play only a small role in aiding pollination, with the process being mostly self-contained within the vine. But
cross-pollination
Pollination is the transfer of pollen from an anther of a plant to the stigma of a plant, later enabling fertilisation and the production of seeds, most often by an animal or by wind. Pollinating agents can be animals such as insects, birds, ...
between vines of different varieties is possible:
Cabernet Sauvignon
Cabernet Sauvignon () is one of the world's most widely recognized red wine grape varieties. It is grown in nearly every major wine producing country among a diverse spectrum of climates from Australia and British Columbia, Canada to Lebanon' ...
is a cross of
Cabernet Franc
Cabernet Franc is one of the major black grape varieties worldwide. It is principally grown for blending with Cabernet Sauvignon and Merlot in the Bordeaux style, but can also be vinified alone, as in the Loire's Chinon. In addition to being us ...
and
Sauvignon blanc
is a green-skinned grape variety that originates from the Bordeaux region of France. The grape most likely gets its name from the French words ''sauvage'' ("wild") and ''blanc'' ("white") due to its early origins as an indigenous grape in ...
;
Petite Sirah is a cross of
Syrah
Syrah (), also known as Shiraz, is a dark-skinned grape variety grown throughout the world and used primarily to produce red wine. In 1999, Syrah was found to be the offspring of two obscure grapes from southeastern France, Dureza and Mondeuse B ...
and
Peloursin
Peloursin is red French wine grape variety best known for crossing with Syrah to make the red wine grape Durif (known in the United States as Petite Sirah).J. Robinson ''"The Oxford Companion to Wine"'' Third Edition pg 510 Oxford University P ...
. During the process of fertilization, the pollen fertilizes the ovary which produces seeds as the flower begins the transformation into a grape berry, encapsulating the seed. Detrimental weather (cold, wind & rain) can severely affect the flowering process, causing many flowers not to be fertilized and produce a group.
It is during this time when the buds that will become next years crops begin to form.
Fruit set
![Young grapes](https://upload.wikimedia.org/wikipedia/commons/6/66/Young_grapes.jpg)
The stage of fruit set follows flowering almost immediately, when the fertilized flower begins to develop a seed and grape berry to protect the seed. In the Northern Hemisphere, this normally takes place in May and in the Southern Hemisphere in November.
This stage is very critical for wine production since it determines the potential crop
yield. Not every flower on the vine gets fertilized, with the unfertilized flowers eventually falling off the vine. The percentage of fertilized flowers averages around 30 but can get as high as 60 or be much lower. Climate and the health of the vine play an important role with low
humidity
Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation, dew, or fog to be present.
Humidity depe ...
, high temperatures and water stress having the potential of severely reducing the amount flowers that get fertilized.
Coulure occurs when there is an imbalance of carbohydrate levels in the vine tissues and some berries fail to set or simply fall off the bunch. Varieties like
Grenache
Grenache () or Garnacha () is one of the most widely planted red wine grape varieties in the world. Niels Lillelund: ''Rhône-Vinene'' p. 25, JP Bøger – JP/Politikens Forlagshus A/S, 2004. . It ripens late, so it needs hot, dry conditi ...
and
Malbec are prone to this abnormal fruit set.
Millerandage
Millerandage (or shot berries, hens and chicks and pumpkins and peas) is a potential viticultural hazard problem in which grape bunches contain berries that differ greatly in size and, most importantly, maturity. Its most common cause is cold, rain ...
occurs when some fertilized flowers do not form seeds but only small berry clusters. Grape berry size depends on the number of seeds so berries with no seeds will be significantly smaller than berries containing seeds. On one cluster there may be berries of various sizes which can create problems during winemaking due to the varying "skin to pulp" ratio among the grapes.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 291 Oxford University Press 2006 ] This can be caused by vine disease, such as
fanleaf, or by a
boron
Boron is a chemical element with the symbol B and atomic number 5. In its crystalline form it is a brittle, dark, lustrous metalloid; in its amorphous form it is a brown powder. As the lightest element of the ''boron group'' it has th ...
deficiency in the vine.
Gewürztraminer and the Chardonnay
clones IA and Mendoza are both prone to millerandage.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 443 Oxford University Press 2006 ]
Veraison
![Véraison](https://upload.wikimedia.org/wikipedia/commons/8/87/V%C3%A9raison.JPG)
Following fruit set, the grape berries are green and hard to the touch. They have very little
sugar
Sugar is the generic name for sweet-tasting, soluble carbohydrates, many of which are used in food. Simple sugars, also called monosaccharides, include glucose, fructose, and galactose. Compound sugars, also called disaccharides or double ...
and are high in organic acids. They begin to grow to about half their final size when they enter the stage of veraison. This stage signals the beginning of the
ripening process and normally takes place around 40–50 days after fruit set. In the Northern Hemisphere this will be around the end of July and into August and between the end of January into February for the Southern Hemisphere.
During this stage the colors of the grape take form—red/black or yellow/green depending on the grape varieties. This color changing is due to the
chlorophyll
Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...
in the berry skin being replaced by
anthocyanins (red wine grapes) and
carotenoids (white wine grapes). In a process known as
engustment
In viticulture, ripeness is the completion of the ripening process of wine grapes on the vine which signals the beginning of harvest (wine), harvest. What exactly constitutes ripeness will vary depending on what style of wine is being produced (sp ...
, the berries start to soften as they build up
sugars. Within six days of the start of veraison, the berries begin to grow dramatically as they accumulate
glucose
Glucose is a simple sugar with the molecular formula . Glucose is overall the most abundant monosaccharide, a subcategory of carbohydrates. Glucose is mainly made by plants and most algae during photosynthesis from water and carbon dioxide, using ...
and
fructose
Fructose, or fruit sugar, is a Ketose, ketonic monosaccharide, simple sugar found in many plants, where it is often bonded to glucose to form the disaccharide sucrose. It is one of the three dietary monosaccharides, along with glucose and galacto ...
and acids begin to fall.
[J. Robinson (ed) ''"The Oxford Companion to Wine"'' Third Edition pg 730 Oxford University Press 2006 ]
The onset of veraison does not occur uniformly among all berries. Typically the berries and clusters that are most exposed to warmth, on the outer extents of the
canopy, undergo veraison first with the berries and clusters closer to the trunk and under the canopy shade undergoing it last. There are some factors in the vineyards that can control the onset of veraison, limited
water stress
Water scarcity (closely related to water stress or water crisis) is the lack of fresh water resources to meet the standard water demand. There are two types of water scarcity: physical or economic water scarcity. Physical water scarcity is where ...
and canopy management that creates a high "fruit to leaf" ratio can encourage veraison. This is because the vine is biologically programmed to channel all its energies and resources into the berries, which houses its seedling offspring, to provide them a better chance of survival. Conversely, very vigorous vines with plentiful leaf shading for photosynthesis and water supply will delay the start of veraison due to the vines energies being directed towards continued shoot growth of new buds. For the production of high-quality wine, it is considered ideal to have an earlier veraison. During this period the cane of the vine starts to ripen as well changing from green and springing to brown and hard. The vines begins to divert some of its energy production into its reserves in preparation for its next growth cycle.
After harvest
![Grape gathering](https://upload.wikimedia.org/wikipedia/commons/9/9c/Grape_gathering.jpg)
In the vineyard, the antepenultimate event is the
harvest
Harvesting is the process of gathering a ripe crop from the fields. Reaping is the cutting of grain or pulse for harvest, typically using a scythe, sickle, or reaper. On smaller farms with minimal mechanization, harvesting is the most labor-i ...
in which the grapes are removed from the vine and transported to the winery to begin the wine making process. In the Northern Hemisphere this is generally between September and October while in the Southern Hemisphere it is generally between February and April. The time of harvest depends on a variety of factors-most notably the subjective determination of
ripeness
In United States law, ripeness refers to the readiness of a case for litigation; "a claim is not ripe for adjudication if it rests upon contingent future events that may not occur as anticipated, or indeed may not occur at all." For example, if a ...
. As the grape ripens on the vines, sugars and
pH increase as acids (such as
malic acid
Malic acid is an organic compound with the molecular formula . It is a dicarboxylic acid that is made by all living organisms, contributes to the sour taste of fruits, and is used as a food additive. Malic acid has two stereoisomeric forms ...
) decrease.
Tannin
Tannins (or tannoids) are a class of astringent, polyphenolic biomolecules that bind to and precipitate proteins and various other organic compounds including amino acids and alkaloids.
The term ''tannin'' (from Anglo-Norman ''tanner'', ...
s and other
phenolic
Phenolic is an adjective and a substantive (noun) that may apply to :
* Phenol (or carbolic acid), a colorless crystalline solid and aromatic compound
* Phenols, a class of chemical compounds that include phenol
* Phenolic content in wine
* Phenol ...
s also develop which can affect the flavors and aromas in the resulting wine. The threat of detrimental weather and vine diseases (such as
grey rot
''Botrytis cinerea'' is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or ...
) can also play a role in the time table. The balance of all these factors contributes to when a winemaker or vineyard manager decides that it is time to harvest.
Following the harvest, the vines continue the process of photosynthesis, creating carbohydrate reserves to store in the vine's roots and trunks. It will continue doing this until an appropriate level of reserves have been stored. At that point the chlorophyll in the leaves begins to break down and the leaves change color from green to yellow. Following the first frost the leaves begin to fall as the vine starts to enter its winter dormancy period. The following spring, the cycle begins again.
See also
*
BBCH-scale (grape) In biology, the BBCH-scale for grapes describes the phenological development of grapes using the BBCH-scale.
The phenological growth stages and BBCH-identification keys of grapes are:
See also
*Annual growth cycle of grapevines
The annual grow ...
References
External links
Annual Cycle of the Grapevine
Stages of Grape Berry Development information from Cooperative Extension
{{Viticulture
Viticulture