The Determinants Of Grape Regions

Climate, soil, site, the surface features of the land, insects, fungi
and commercial geography are the chief factors that determine regions
for money-making in grape-growing. This has been made plain in the
foregoing discussion of grape regions, but the several factors must be
taken up in greater detail. To bound the regions is of less importance
than to understand why they exist--less needful to remember, more
needful to understand. From what has been said, the reader has no
doubt already concluded that successful grape-growing is in largest
measure due to kindliness in climate.

Climate

Under the assumption, then, that climate, of all factors, is chief in
playing providence to the grape, let us examine somewhat critically
the relations of climate to grape-growing. When analyzed, the
essentials of climate, as it governs grape-growing, are found to be
six: first, length of season; second, seasonal sum of heat; third,
amount of humidity in summer weather; fourth, dates of spring and
autumn frosts; fifth, winter temperature; sixth, air currents.

Length of season.

To reach true perfection, each grape variety has a length of season of
its own. With each, if it is grown in too low a latitude, the vine is
uninterrupted in growth; its leaves tend to become evergreen; and not
infrequently it produces at the same time blossoms, green fruits and
ripe fruits. This is, of course, the extreme to which grapes pass in
the far South. Again, many northern varieties fail where southern
grapes succeed because the fruits pass too rapidly from maturity to
decay. On the other hand, very often southern grapes are hardy in vine
in the North, but the season is not sufficiently long for the fruit to
mature and to acquire sufficient sugar to give them good keeping
quality, properly to pass through vinous fermentation, or even to make
a good unfermented grape-juice. In the uneven topography of this
continent, it is not possible to state the range in latitude in which
grapes can be cultivated to advantage, for latitude is often set aside
by altitude. Thus, isothermal lines, or lines of equal temperature,
are much curved in America and do not at all coincide with the
parallels of latitude.

Other factors, of course, than length of season enter into the
ripening of grapes. The daily range in temperature, not always
dependent on latitude, affects ripening. Cool nights may offset warm
days and delay ripening. Certainly rains, fogs and humid air delay
maturity. The bottom heat of loose, warm, dry gravelly or stony soils
hastens maturity. Sunshine secured by a sunny aspect or shelter
hastens maturity.

The seasonal sum of heat.

Successful cultivation of the grape depends on a sufficient amount of
heat during the summer season. The theory is that buds of the grape
commence to start when the mean daily temperature reaches a certain
height, and that the sum of the mean daily temperature must reach a
certain amount before grapes ripen. Manifestly, this sum must vary
much with different varieties, low for the earliest sorts, high for
the latest. There have been many observations as to the temperatures
at which buds of the grape start growth, so that it is now known that
the temperature varies in accordance with locality and degree of
maturity. Roughly speaking, grape buds start at temperatures from 50 deg.
to 60 deg. F. The seasonal sum of heat for ripening is probably 1600 to
2400 units. A variety ought not to be planted, therefore, in a region
in which the average seasonal sum of heat is not sufficiently high.
The seasonal sum of heat can be determined for a locality from data
published by the United States Weather Bureau; and by comparing with
the sum of heat units in localities where a variety is known to
thrive, the grape-grower can determine whether there is sufficient
heat for any particular variety.

The grape seldom suffers from hot weather in a grape region. The fruit
is sometimes scalded in the full blaze of a hot sun, but the ample
foliage of the vine usually furnishes protection against a burning
sun. At maturing time, the heat of an unclouded sun, if the air
circulates freely, insures a finely finished product. Deep planting
helps to offset the harmful influences of warm climates.

Humidity of summer weather.

The grape is very sensitive to moisture conditions, and grows best in
regions where the summer rainfall is comparatively light. A damp and
cloudy summer brings disaster to the vineyard in several ways; as
small growth of vine, small set of fruit, a crop of poor quality, and
the development of the several fungous diseases. Although the grape
stands drought, a superfluity of moisture in the soil may do little
harm, as is shown in irrigated vineyards, but a humid air is fatal to
success especially if the air is both warm and wet. Moist weather
during the time of maturity is particularly disastrous to the grape,
as are frequent fogs. Cold wet weather in blooming time is the
grape-grower's vernal bane, since it most effectually prevents the
setting of fruit. It may be laid down as a rule that the grape lives
by sunlight, warmth and air--it often thrives on the desert's edge.
These considerations make it manifest that the monthly and seasonal
means of precipitation must be considered in selecting a locality to
grow grapes.

Spring and autumn frosts.

The average date at which the last killing frost occurs in the spring
often determines the limit in latitude at which the grape can be
grown. Even in the most favored grape region of the continent, killing
frosts occasionally destroy the grape crop, and there are few seasons
in which frost does not take some toll. Thus on May 7, 1916, frost all
but ruined the crop of wine- and table-grapes in the great grape
region of northern California where frosts are seldom expected in May.
Little or nothing can be done to protect grapes from frost. Windbreaks
as often favor the frost as the vine, and smudging or heating the
vineyards is too expensive to be practical. In growing grapes,
therefore, the commonly recognized precaution of selecting a site
near water, on slopes or in a warm thermal belt must be exercised.

The limits of grape culture are also determined by early autumn
frosts. The grape stands two or three degrees of frost, but anything
lower usually destroys the crop. Here, again, the only precaution is
to take pains in selecting the site.

The use of weather data and dates of life events of the grape.

These considerations of length of season, humidity and spring and fall
frosts make it plain that the grape-grower must synchronize these
phases of climate with the life events of the grape. In particular, he
must study weather data in relation to the blooming and ripening of
grapes. Usually, the necessary weather data may be secured from the
nearest local weather bureau, while the date of blooming and ripening
may be obtained from the state experiment stations in the states where
the grape is an important crop.

Winter temperature.

Varieties of native grapes are seldom injured in America by
winter-killing, since they are usually planted in climates in which
wild grapes withstand winter conditions. Native varieties follow the
rule that plant and climate are truly congenial in regions in which
the plant thrives without the aid of man. A few varieties of native
grapes fare badly in the winter's cold of northern grape regions, and
the tender Vinifera vine is at the mercy of the winter wherever the
mercury goes below zero. In cold climates, therefore, care must be
exercised in selecting hardy varieties and in following careful
cultural methods with the tender sorts. If other climatic conditions
are favorable, however, winter-killing is not an unsurmountable
difficulty, since the grape is easily protected from cold, so easily
that the tender Viniferas may be grown in the cold North with winter
protection.

Air currents.

Currents of air are of but local importance in growing tree-fruits,
but are of general and vital importance in growing the grape. The
direction, force and frequency of prevailing winds are often
controlling factors in the suppression of fungous diseases of the
grape, and the presence of fungi often means success or failure in
regions in which the grape is planted. Winds are beneficial, too, when
they bring warm air or dry air, and when they keep frosty air in
motion. The air must move in all grape regions, whether from canon,
mountain, lake or sea. Sunlight, warmth, and air in motion are life to
the grape. Sometimes winds may be detrimental; as when too cold, too
blustering, or when they bring hail, the latter being about the most
disastrous of all natural calamities. Windbreaks are of small value
and are often worse than useless. Having planted his vineyard, the
grape-grower must take the winds as they blow.

Soils for grapes

A prime requisite for a vineyard being earth in which vines will grow,
successful grape-growing is eminently dependent on the selection of
soil. Many mistakes are made in the great grape regions in planting on
unsuitable soils, the planter going on the assumption that any soil in
a grape region should be good enough for the grape. But the crust of
the earth in grape regions is not all grape soil. In New York, for
example, much of the land in the three grape regions is better fitted
for producing crops for the mason or road-mender than for the
grape-grower. Other soils in these regions are fit for vineyards only
when tiled, and tiling does not make all wet land fit for tilling.
Heavy, clammy clays, light sands, soils parched with thirst, thin or
hungry soils--on all of these the grower may plant but will seldom
harvest.

The ideal soil.

Grapes may be well grown in a wide range of soils if the land is well
drained, open to air and if it holds heat. But without these
essentials, whatever the soil, all subsequent treatment fails to
produce a good vineyard. Generally speaking, the grape grows best in a
light, free-working, gravelly loam, but there are many good vineyards
in gravelly or stony clays, gravel or stone to furnish drainage, let
in the air and to hold heat. Contrary to general belief, the grape
seldom thrives in very sandy soils unless there is a fair admixture of
clay, considerable decomposing vegetable matter and a clay subsoil.
The latter, however, must not come too close to the surface. Some of
the best vineyard lands in the country are very stony, the stones
hindering only in making the land difficult to till. Nearly all grapes
require a friable soil, compactness being a serious defect. Virgil,
writing in Christ's time, gave good advice as to soil for the vine:

"A free loose earth is what the vines demand,
Where wind and frost have help'd the lab'rer's hand,
And sturdy peasants deep have stirr'd the land."

Cold, churlish, sticky or clammy clays are never to the liking of the
grape.

Great fertility is not necessary in grape lands. Indeed, the grape is
conspicuous among cultivated plants for ability to nourish itself
where the food supply is scant. Soils naturally too rich produce an
overgrowth of vine, the season's wood does not mature, the crop does
not set, and the grapes lack sugar, size, color and flavor. Good
physical condition and warmth in a well-watered, well-aired soil
enable the grape to search far and wide for its food.

Drainage.

No cultivated grape endures a wet soil; all demand drainage. A few
sorts may thrive for a time in moist, heavy land, but more often they
do not live though they may linger. The water-table should be at least
two feet from the surface. If by chance this comes naturally, so much
the better, but otherwise the land must be tile-drained. Sloping land
is by no means always well drained, many hillsides having a subsoil so
impervious or so retentive of moisture that under-drainage is a
necessity. The texture of the land is usually improved so greatly by
good drainage that the grower has little need to rely on the clemency
of the season in carrying on vineyard cultivation in well-drained
land.

Soil adaptations.

In the refinement of viticulture, grape-growers find that particular
varieties grow best in a particular soil, the likes and dislikes being
determined only by trial, for the peculiarities which adapt a soil to
a variety are not analyzable. Some varieties, on the other hand, the
Concord being a good example, grow fruitfully in a great variety of
soils. Each of the several species with their varieties has quite
distinct adaptations to soils. This is taken advantage of in planting
varieties on uncongenial soils after they have been grafted on a vine
which finds itself at home in the particular soil. Much has been
accomplished in growing varieties on uncongenial soils by consorting
them with other stocks, an operation which has brought forth volumes
of discussion as to the adaptabilities of cions to stocks and stocks
to soils, subjects to receive attention on a later page.

Insects and fungi

The profitable grape regions of the country have all been established
in regions comparatively free from grape insects and fungi. If pests
came later in considerable numbers, the industry, in the old days,
perished. Here and there in the agricultural regions of the country
may be found a sorry company of halt and maimed vines, remnants of
once flourishing vineyards, brought to their miserable condition by
some scourge of insects or fungi. The advent of spraying and of better
knowledge of the habits of the pests has greatly lessened the
importance of parasites as a factor in determining the value of a
region for grape-growing; but even in the light of the new knowledge,
it is not wise to go against Nature in regions where pests are
strongly intrenched.

Commercial factors

The dominant factors that lead to the planting of large areas to any
one fruit are often economic ones; as transportation, markets, labor,
facilities for making by-products, and opportunity to join in buying
and selling organizations. All of these factors play an important part
in determining the bounds of grape regions, but a lesser part than in
the establishment of large areas of other fruits, for the reason that
the grape is so largely grown for raisins, wine, champagne and
grape-juice, products condensed in form, made with little labor,
easily transported, which keep long and find ready market at any time.
Again, where natural conditions are favorable for grape-growing, the
crop comes almost as a gift from Nature; whereas, if the grower must
breast the blows of unfavorable natural circumstances, no matter how
favorable the economic factors may be, the vineyard is seldom
profitable. Natural factors, therefore, outweigh economic ones in
grape-growing, but the latter must be considered in seeking a site for
a vineyard, a task discussed under several heads to follow.

Accessibility to markets.

Markets ought to be accessible in commercial grape-growing. A location
in which there is a good local market, and at the same time ample
facilities for shipping to distant markets, is desirable. If there
are also opportunities to dispose of any surplus to makers of raisins,
wine or grape-juice, the grower has well-nigh attained the ideal.
Further to be desired are good roads, short hauls, quick
transportation, reasonable freight rates, refrigerator service and
cooeperative agencies. The more of these advantages a grower has at his
disposal, the less likely he is to fail in commercial competition.

General versus local markets.

The grower must be reminded rather than informed that he must decide
in locating his vineyard whether he will grow for distant markets, for
manufacturing into grape products, or for local markets. Determination
to grow grapes once made, subsequent procedure at every step depends
on the disposition to be made of the product. Summarized, the
differences in growing grapes for the two markets are: For the general
market: the acreage should be large; the market may be distant; the
varieties few; the cost of production low; sales large and prices low;
the dealings are with middlemen; and extensive culture is practiced.
For the local market: the acreage may be small; the market must be
near and prices must be high; the sales are direct to the consumer;
there must be succession in ripening; and intensive culture is
practiced. For the general market, the vineyard is the unit; for the
local market, the variety should be the unit. In this discussion,
however, "large acreage" and "extensive culture" set against "small
acreage" and "intensive culture" may mislead. This is a case in which
a large endeavor may be a small endeavor, and a small endeavor a large
one; or, in which it may be well to take the advice of Virgil, who
advised Roman vineyardists, "Praise great estates; farm a small one."

The grape-growing of the times tends more and more to growing for
general markets. The grower plants to skim a comparatively small
return from a large area. This division of grape-growing is now well
developed in America. Intensive grape-growing for local markets is not
well developed. There are, however, many opportunities in America for
easy triumphs in fruit-growing in the planting of vineyards for local
markets. No other fruit responds to fine art in culture so well as the
grape. Given choicely good varieties and a finely finished product,
and the grower may have almost what he desires for the produce of his
skill. With the grape, too, palm of merit goes with skill in culture;
among all who grow plants, only the florist can rival the
viticulturist in guiding the development of a plant to a special end.
In cultivating, fertilizing, training, grafting, pruning, spraying, in
every cultural operation, the grape-grower has opportunities to sell
his skill not given in so high degree to the grower of other fruits.

Labor.

A great advantage in the congregation of vineyardists in grape regions
is found when labor must be obtained. Skilled labor is required to
cultivate the vine, and such labor can be freely secured only in
centers of viticulture. Grape-growing is a specialists' business, and
it takes more than a day or a season to make a vine-dresser out of a
farmer, gardener or an orchardist. Expert labor is most easily
obtained and is of best quality where grapes abound. Common labor must
be somewhat abundant, also, in good vineyard locations, for such rush
tasks as tying and picking. In these two operations, women, children
or other unskilled labor may be employed to advantage. The grape
harvest must often be hurried, and to keep it in full swing a near-by
city from which to draw pickers is a great asset.

Vineyard sites.

Within a grape region, the site is important in determining where to
plant. The site is the local position of the vineyard. Sites cannot
be standardized, and therefore no two are alike. The cardinal natural
factors to be secured in a site are warmth, sun, air and freedom from
frost. These factors have been discussed in a general way under the
climate of grape regions, but one needs to particularize a little more
closely to ascertain how they affect individual vineyards. Warmth,
sun, air and frostlessness are best secured by proximity to water,
high land and proper exposure.

Proximity to water.

The favorable influences of water are well illustrated in the grape
regions of New York, Pennsylvania, Ohio and Canada. All of the grape
districts in these regions are bounded on one or more sides by water.
The equalizing effects of large bodies of water on temperature, warmer
winter and cooler summer, are so well known as scarcely to need
comment. Hardly less important than the effects of water on
temperature are the off-shore breezes of night and the in-shore
breezes of day which blow on large bodies of water. These keep the air
of the vineyard in constant motion and so prevent frosts in spring and
autumn, and also dry foliage and fruit so that spores of fungi have
difficulty in finding foothold. But if water brings fogs, dews and
humidity, as does the Pacific, grapes must be planted inland;
otherwise leaf, bloom and fruit are born in the blight of fungi. The
benign influences of water are felt in the eastern grape regions at
distances of one to four miles, seldom farther. These narrow belts
about the eastern waters are bounded on the landward side by high
bluffs over which many showers fail to pass and which protect the
belts below from heavy dews. Where the background of bluffs in these
regions sinks to level land, vineyards cease.

Vineyards are usually some distance above the water, the range in
altitude running from fifty to five hundred feet. Where the altitude
is much higher, immunity to frosts and winter freezing ceases, for
the reason that the atmosphere is rarer and drier so that heat
radiates rapidly from the land. As the height increases, also, the
revels of the wind play havoc with the vines. Yet, one is often
surprised to find good vineyards at the level of the lakes or, on the
other hand, crowning high hills. Altitude in grape-growing must,
therefore, be determined by experiment. We know very little of the
formation of the thermal belts on high land so favorable to the grape.

The lay of the land.

We associate the grape with rugged land; as the vines on the banks of
the Rhine, the rolling lands of Burgundy, the slopes of Vesuvius and
Olympus, the high hills of Madeira, the cloud-capped mountains of
Teneriffe, mountain slopes in California and the escarpments of grape
regions in eastern America. These examples prove how well adapted
rolling lands, inclined plains and even steep and rocky hillsides are
to the culture of the vine. Virgil long ago wrote, "Bacchus is partial
to broad, sunny hills." Yet rolling lands are not essential to the
culture of the grape, for in Europe and America very good grapes are
grown on unsheltered plains, provided the land has an elevation on one
or more boundaries above the surrounding country. If the conditions of
soil and climate which the grape requires can be found on level land
or moderate slopes, such situations are much better than steep
declivities, since on these the cost of all vineyard operations is
greater and heavy rains erode the soil. The soil on hills, too, is
often scant and niggardly. Level land, however, must not be shut in on
all sides by higher land as untimely frost will often lay waste vines
in such a situation.

Exposures.

The exposure, or the slope of the land toward a point of the compass,
is important in choosing a site for the vineyard, although the value
of particular exposures is often exaggerated. Let it be remembered
that good grapes may be grown in vineyards exposed to any point of the
compass, but that slight advantages may sometimes come, depending on
the particular environment of the plantation, and then solve the
problem according to conditions. The following are theories as to
exposure: A southern exposure is warmer and hence earlier than a
northern, and is, therefore, the best slope for early grapes as well
as for very late ones liable to be caught by frost. Northward and
westward slopes retard the leafing and blooming period, thus often
enabling the grape to escape untimely spring frosts; though to plant
on such slopes may be robbing Peter to pay Paul, as what is gained in
retardation in spring may be lost in the fall with the result that the
vines may be caught by frost and may fail to ripen their crop. Frost
damage is usually greatest on a bold eastern slope, and vines suffer
most in winter freezes on this exposure, since the direct rays of the
rising sun strike the frozen plants so that they are more injured than
otherwise by rapid thawing. In locations near bodies of water, the
best slope is toward the water, regardless of direction. The exposure
may sometimes be selected to advantage with reference to the
prevailing winds.

Next: Propagation
Previous: The Grape Regions Of America

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