Viticulture is the science
of growing grapes.
The world wine producing zones lie between
and south latitutudes.
Climate is the general long-term weather pattern
for a region.
The Heat Summation System defines growing regions
of grapes based on temperature.
Frost can damage vines in early spring as well
as the plant's dormant period.
Hail is unpredictable and can easily damage vines.
Heat stress slows down photosynthesis in the
Poor weather can lead to coulure and millerandage.
The type of soil and components found within
it determine how well grapes grow.
Organic viticulture uses natural means to rid
the grapes of pests.
Terroir, the French word for earth or soil,
is used to describe all the attributes which
combine to make one location different from another.
Vitis vinifera is the scientific
name for the most common grape used in winemaking.
Crossings, hybrids, and clones are methods
viticulturists use to produce new varieties of Vitis vinifera.
Phylloxera is the insect that accounts for more
lost crops of grapes than any other pest.
Pruning and Training
Pruning and training the grapes is done to
control and support grapevines during growth.
Vineyard Annual Chart
A chart on the annual cycle
of grapevines summarizes
what is done at the vineyard month by month.
Viticulture is the science and
practice of grape growing. People engaged in this business are called
viticulturalists or are sometimes
referred to as grape-growers or even vine-growers. Their practices
vary tremendously around the world and are influenced by the local
toppography, the climate and soil. Many of their practices affect
the grapes that are eventually harvested to make wine, like soil
preparation, choice of vine variety and rootstock, vine density,
vine pruning and trellising, irrigation, control of pests and dieseases,
and methods of harvesting. This section will look at the important
issues of viticulture including climate, soil, vines, pruning and
training, trllising, organic viticulture, and harvesting.
Vines grow in a wide variety
of climates throughout the world and
continue to expand to new regions and climates. Vines
and grapes do not like extremes of temperatures and so, for the most
part, are located in the temperate zones between 30° and 50° either
north or south of the equator. Vines have difficulty growing above
90° F and below 50° F. Winter frosts below -15° F can
also stymie vine development. Vines also do best where there is a
dormant period of about six months. In the Norhtern Hemisphere, the
most northerly zones for growing wines is around 52° N which
is the latitude for British Colombia and Southern England. In the
Hemisphere, the most southerly wine growing region is about 46° S
in Otago, New Zealand. A look at the digram below shows the bands
of climates condusive to vine-growing. You may realize
that there is still great potential for grape growing throughout
the world in areas including Eastern Europe, parts of the former
Soviet Union, and China. In any case, the best quality grapes are
grown where there is a relatively long and cool ripening period.
While climate, or macroclimate,
is generally understood to be the general, long-term weather pattern
of any given region, two related
terms should be specified. The word mesoclimate is used to refer
to the weather of a specific site. It encompasses the influence of
local topography and so would refer to the weather of a particular
vineyard or contiguous vineyard of similar aspect. Microclimate is
usually reserved for the climate in a very restricted place such
as a specific row or section of a row of vines. Some experts even
confine a microclimate to within the area immediately surrounding
a vine's canopy. Generelly, when a vineyard is planted, not only
is it important to look at the macroclimate, but site preparation
and desing should take in to account the mesoclimate and, perhaps
In order to compare wine regions
around the world, various systems have been developed so that these
have a scientific
basis. In the United States, a common method for comparing the temperature
of wine growing areas was devised by and is name after Albert J.
winkler of the University of California. This system, which is sometimes
referred to as the Heat Summation System, measures
monthly average temperatures above 50° F for the growing season (below 50° F
the vine does not grow). Winkler delineated five growing regions
based on the temperature findings:
|Winkler's Heat Summation System
|Region I (the coolest)
||the best for dry tables wines of light body (Carneros)
||the best for dry table wines of medium body (Stags Leap)
||the best for full-bodied dry and sweet wines (Calistoga)
||best for fortified wines
||best for table grapes and drying grapes
While this system has proven successful and is widely used in California,
it is not fully accepted elswehere because in other regions, such
as coastal Australia and New Zealand, temperature alone is a poor
indicator of viticultural climates.
One climatic condition that affects the vine similarly throughout
the world is frost. It is mainly a problem during the springtime
but can also hurt dormant vines during the winter. Ice can form in
the plant tussue of buds, young shoots , or leaves which will turn
brown and die. Moisture in the wood may freeze, crackin or splitting
the trunk, which could lead to loss of the entire vine. this is particularly
true of late frosts that occur after teh sap has already begun to
rise in the vines. There are many methods to prevent frost damage.
Wind machines, such as the lare motor-driven propellers widely used
in California, circulcate warm and cold air through the vineyard.
heaters and oilburners are used to rasise temperatures. Another method
is aspersion, or sprinkling water over the vines. the release of
latent heast as the water freezed on the vines protects the vine
tissue from injury.
Hailstorms are a thoroughly unpredictable climatic problem for which
there is little relief save for taking out a costly insurance policy.
Hail can strip a vine of its leaves, break off shoots, or damage
the young fruit. Even though methods have been tried, like firing
rockets carrying silver iodide into the cloud formation in an attempt
to convert the hail to rain, no reliable method has yet to be developed
to prevent this kind of damage.
Vines can suffer heat stress, which
happens in areas where daytime temperatures approach or exceed
This is true in many areas of California, Spain, and Southern Italy.
cause photosynthesis to slow or stop, reducing levels of malic acids
in the grapes. Heat stress, as well as sunburn, is fairly easily
controlled through canopy management.
A region's climate is relatively
fixed, but its weather may vary from year to year. Ideally, heavy
ground water reserves and is followed by a mild spring which encourages
budbreak and successful flowering. Poor weather, notably cold, cloudy
wet days, at flowering time can cause what is known as coulure. Coulure
is when low temperatures cause incomplete fertilization and the unfertilized
flowers drop off reducing the ultimate size of the harvest. Coulure
is typically followed by millerandage where improperly
fertilized flowers stay on the vine but fail to expand and swell
into full size
grapes. This leads to irregular ripening and perhaps a lengthy and
difficult harvest. Rain at harvest time can cause rot, so most growers
hope for a dry harvest season.
Vines grow in many different types of soils, the variations of which
are among the many factors that affect the quality of wine. Vines
thrive in some very inhospitable and seemingly arid soils, stretching
their roots deep into the sub-structure. Heavy clay soils should
be avoided because vines do not generally do well where there is
poor drainage. More importance should be placed on the organic content
of the soil which in most cases needs to be replenished yearly. In
order to grow proplerly, vines need the correct level of fertilizers
in the soil, which means measuring and adjusting levels of magnesium,
postassium, nitrogen, and other minerals.
Replenishing the soil with
these and other nutrients is increasingly being done through organic
While its practice has many
definitions, organic viticulture generally implies growing grapes
without synthetic fertilizers, pesticides, or other growth regulators.
Only microbiological products from plant, animal or mineral substances
ar applied to the soil. In California, an organic wine must abide
by the California Foods Act of 1990 and be labeled as such. It may
also be certified by the California Certified Organic Farmers (CCOF).
Other states are following suit and in France it's either Nature
et Progrès, Terre et Vie or the UNIA -Interprofessional National
Union of Agrabilogy - that oversees organic viticulture. It's important
to note that, for American wines, there is a difference between
"organically grown and processed" and "organically
grown grapes." The latter term reflects the usage of sulfites.
Sulfur is used in winemaking as an anti-bacterial agent and as an
do occur naturally though, and so the warnings on labels are directed
at the less than 0.4% of the population that may be allergic to sulfites.
The relationship of soil quality to wine is not fully understood.
It's generally agreed upon that the supply of water through the
soil is one of the most important factors and that good drainage
is important. Generally, vines do well in gravelly soils, that are
moderately deep. It can be concluded that soil characteristics do
influence the wine's quality and its character, but to what extent
Some viticulturalists place
more importance on a vineyard's site and soil than others. They
support the concept
of terroir. The French
term which literally means "the soil or the earth," is
used in the world of wines to describe the marriage of soil, climate,
grape variety planted there. An example would be the gravelly soil,
cool maritime climate and Cabernet Sauvignon in the Médoc.
Riesling, the slate soil and the cool, continental climate of the
Mosel, is another example. In the New World, terroir may not have
had great support in the past , but is becoming increasingly important.
One of the most common vine species is Vitis vinifera, which
literally means "the wine vine." Vitis is the genus and
vinifera is the species. There are other wine producing species of
such as Vitis labrusca, Vitis riparia and Vitus
repestris. However, it is Vitis vinifera that accounts
for more than 99% of all the wines consumed in the world. It is native
to Europe as well as East and Central Asia, but it has been planted
the world. There are estimated to be thousands of varieties of this
species, some of the best known being cabernet sauvignon, chardonnay,
chenin blanc, merlot, pinot noir, riesling, sauvignon blanc, syrah,
and zinfandel. Each variety of grape
has its own idiosyncrasies and contributes different qualities to
New varieties of Vitis vinifera can
be produced and they are called crossings. This
is done by fertilizing the flower of one
variety with the pollen of a different variety, followed by the planting
of the resultant grape seeds and seedlings. The attempt is to garnish
the benefits of both varieties. Few crossing have attained any prominence
although some are important. Müller-Thurgau is a crossing that
combines the quality of Riesling and the early ripening of Silvaner.
Kerner is a crossing between Riesling and Trollinger and Pinotage
is a crossing between Pinot Noir and Cinsault.
A slight variation on a crossing is a hybrid, sometimes referred
to as an interspecific crossing. This is the offspring of two varieties
of different species. Catawba is a a good example of an American
hybrid coming from the parents Vitis vinifera and Vitis
labrusca. Hybrids have little commercial viability.
Viticulturalists are constantly trying to imporve their crops and
so may uses certain clones of a particular variety to achieve optimum
quality. Clonal selection is the practrice of selecting a superior
plant from a vineyard and taking cuttings from this vine for propogation.
Typical cuttings or buds are taken from the mother vine, grafted
onto rootstocks, and planted out for assessment. In this way varieties
can be altered to suit particular circumstances. An example of a
clone is the wine Brunello di Montalcino, which is made from a grape
that is a clonal selection from Sangiovese. California's Gamay Beaujolais
is a clone of Pinot Noir.
Phylloxera is an insect that damages the roots of some species of
vine especially Vitis vinifera. It's a small, yellow aphid
that has caused more damage to the wine business than probably any
or disease. Phylloxera is indigenous to eastern North America and
was probably exported to Europe in the 1860's when American rootstocks
were being used to combat powdery mildew. For nearly fifteen years
it devastated the vineyards of Europe until it was discovered that
the Vitis vinifera varieties could survive if they were
grafted onto American rootstocks. Vineyards in California are now
a similar epidemic. Viticuluralists there have discovered that the
widely used rootstock AxR1 is not as resistant as previously believed.
Only a few wine growing regions - Chile, parts of Australia and New
Zealand - have not been affected by phylloxera.
For more about Phylloxera click
here or here
The Grapevine is a true vine that requires some form of support
to keep it off the ground. In the wild, tendrils along the canes
attach to other vegetation and allow the vine to grow up off the
ground. In our intensive cultural systems, there is no natural support
the vines. Therefore, we have to erect various trellis systems to
train and support the vines, and facilitate other management practices.
Pruning can be defined as “the removal of plant parts to obtain
horticultural objectives”. These objectives include:
| -Controlling the size & form
of the grapevine.
- Optimize the production potential of the grapevine.
- Maintain a balance between vegetative growth and fruiting.
Training can be defined as “the arrangement
of plant parts spatially”.
This is done to develop a structure that:
|- Optimizes the utilization of sunlight and promotes
- Adapts to the characteristics of the grape cultivar.
- Promotes efficient & sustainable vineyard management practices.
- Is economical to establish and maintain.
To have productive grape vines that produce quality fruit, the vines
must be trained and pruned to a definite system. Compared to other
fruit plants in your garden, grapes are pruned rather severely. To
properly prune a grape plant, you must understand some basic terminology
pertaining to grapes:
|Arm or Cordon-- short branch
of wood extending laterally from trunk;
Cane-- one-year-old fruiting wood;
Cane bud-- located at a node on the cane, it produces the
Internodes-- the portion of a stem between two nodes;
Node-- joint on a shoot or cane where buds and leaves are
Renewal spur-- a cane pruned to two buds;
Shoot-- current season growth of wood from bud, produces leaves,
flowers, and fruit;
Spur-- a cane pruned to four or fewer buds;
Sucker-- a shoot that develops from the lower trunk or from
Knowing the fruiting habit of grapes is essential to properly understand grape
pruning. Buds on one-year-old dormant wood (canes) produce next year's shoots
on which the fruit clusters or bunches develop. Each shoot produces from
zero to four or more bunches. There are many training systems for grapes.
Each has its own advantages and disadvantages.
In addition, some systems are better adapted for one cultivar of grape.
While the four-cane Kniffen system is probably the most widely used training
for American hybrid grapes, there are other training systems
that are probably superior. The Single Curtain Cordon system, either High
or Low wire, is probably the best single training system for most of our
To download a pdf file with more information about pruning and training
You will need Adobe Acrobat to open this file. If you need to download
Adobe Acrobat click
The timing of the harvest depends primarily on the ripeness of the
grapes. Weather conditions at the time of harvest are also very important
because rain or dampness can lead to rot. Beofore the main harvest,
a thinning out may take place to remove unripened green fruit. Ideally
grapes are harvested at the optimun balance between sugars and acidity.
Various factors affect the actual timing of vineyard operations.
In warmer areas they take place weeks before cooler regions. Harvest
can take place, depending on the variety and location and desired
style of wine, anywhere from the end of August to the end of November.
This is, or course, for the Northern Hemisphere. The vines cycle
in the Southern Hemisphere is similar but takes place with a difference
of six months. The cycle shown here is for the Northern Hemisphere.
||Pruning of the vines starts.
||Pruning should be completed. Trellising is prepared. Annual
fruiting canes are tied down. Sap begins to rise. Land to be
planted should be prepared. Buds begin to appear.
||Buds break and growth starts. Frost protection is a must. Flower
formation takes place. New vineyards are planted.
||Growth increases. Clusters of flowers form. Frost is still
an issue. Shoot thinning takes place. Pest and disease control
||Early varieties start to flower. Growth continues. Soils are
tilled to control weed growth.
||Flowering is complete. Grapes start to expand.
||Veraison occurs, the transformation of the berries from small,
hard, and green to swelled, softened, and colored.
||Grapes start to sweeten and acidity drops. Pest and disease
control must stop four weeks before harvest. Some leaf trimming
is done to expose grapes to sun and wind to keep disease, mostly
botrytis, to a minimum.. This also speeds harvesting. Harvesting
of early varieties begins.
||Harvest is completed with the exception of some late harvest
varieties. Final soil tilling is completed.
||Pruning may begin where vines are dormant.