Most commercial vineyards sell grapes by the ton and they prefer to sell
their crops to local wineries under long-term contracts. Home winemakers
prefer to purchase grapes by the pound each year, so they are seldom able to
purchase really high quality grapes. Consequently, many San Diego home winemakers are planting
Grapevines are not very fussy. They can be successfully grown in sandy soils,
clay soils and rocky soils. Vines do require full sun exposure, so they will
not do well in a shady spot. In addition to full sun, vines don't like wet
feet, so well drained soils are needed.
Crop size depends on the grape variety, weather, soil conditions, vine
density, water, etc. One to two tons per acre is usual for old, dry farmed
vineyards planted in the cool coastal regions of California. Fruit from old vines often
display concentrated flavors, and the intense flavors carry over into the
wine. On the other hand, heavily fertilized and irrigated vineyards in the Central Valley often produce 12 or more tons per acre.
Fruit quality suffers when production is so high, and such large crops often
result in wine with poor color, low acidity and weak flavors.
In large well-managed vineyards, yields of 3 or 4 tons of grapes per acre can
be expected for quality grape varieties. If an acre contains 600 vines (a
reasonable number) and produces four tons of fruit, each vine is producing
about 13 pounds of grapes. Thirteen pounds of grapes will make about a gallon
of wine, so a gallon of wine per vines is often used as a rough estimate.
But, such yields may be too optimistic for small vineyards. Small, isolated
vineyards are more difficult to manage successfully, and they are much more
susceptible to deer, coyote, rabbit, bird, and bee and wasp damage.
Fifty years ago, vineyard rows were often 12 feet apart, and the vines were
spaced 8 to 10 feet apart in the rows. Many old Cucamonga vineyards were
spaced 12 feet by 12 feet and only contained about 275 vines per acre. Most
of these vineyards were dry farmed, and the wide spacing and free standing
vines allowed the vineyards to be cross cultivated to remove the weeds and
conserved the available water. In recent years, the trend has been to plant
closer spaced vines. Today, new vineyards are being planted with rows spaced
from 7 to 10 feet apart, and the vines are spaced 4 to 8 feet apart in the
rows. The closer vine spacing results in 600 to 1200 vines per acre, and when
adequate trellises are used, the greater vine density can result in larger
crops and higher quality fruit.
Depending on growing condition, vines require 20 or more inches of water per
year. (One inch of rain covering an acre is called an acre-inch and contains
about 27,500 gallons). For normal spacing, vines occupy the space available,
so the annual water required per vine depends on the number of vines per
acre. Vineyards with normal vine spacing and in warm locations may require
500 or so gallons of water per vine per year.
The average rainfall in San Diego
is only about 10 inches per year, and crop size will be very low or even
nonexistent without supplemental water. Since less than half the needed water
is supplied by rainfall, an additional 10 to 20 inches of water will be
needed in most locations. Most local vineyards are irrigated with drip
systems because water is expensive in San Diego County.
Most of the water is lost through the leaves, so the amount of water used by
vines depends primarily on the size of the canopy and the ambient
temperature. Water requirements are very low when vines are dormant, and
water demand is highest in July and August when the canopies are large and
the ambient temperature is high. The water needed by vines varies greatly
with growing conditions, so judging how much water a new vineyard may require
Contractors charge from $15,000 to $35,000 per acre to plant new vineyards on
clear land. These costs include land preparation, an irrigation system, a
trellis system and planting with grafted cuttings. Costs can be even higher
when new vineyards require extensive grading, drilling wells, etc. Home
winemakers often plant their own vineyards, and the savings can be
significant since much of the overall cost is labor. The cost of materials
for a simple 2-wine trellis and a drip irrigation system can range from
$2,000 to $5000 per acre. Sometimes, second hand materials for an irrigation
system or a trellis can be found, and the savings can be considerable.
Grafted vines cost from four to six dollars when purchased in small
quantities. But, Phylloxera is not a problem in San Diego County, so vines can be successfully
grown on their own roots from cuttings. Cuttings are easier to plant than
rooted stock, and cuttings can often be obtained for little or nothing at
Even small vineyards require a significant amount of labor each season. Weeds
must be controlled by cultivation or by spraying with a herbicide each
spring. Most local vineyards must be sprayed or dusted from 2 to 8 times each
year to control powdery mildew and some locations require additional spray
applications to control insect pests. Vines must be pruned each winter, and
most amateurs can only prune 200 vines or so per day, so several days may be
needed to prune an acre. Grapes must be picked promptly when they become
ripe. Picking is hot, dirty work, and under good conditions, most amateurs
will pick a few hundred pounds per day. Picking is much slower when grapes
must be carried long distances out of the vineyard, or when the bees and
wasps are troublesome.
Many home winemakers plant their own vineyard because buying high quality
grapes is difficult. However, considerable time and labor are needed to grow
good grapes. In addition, little crop is produced the first two years, and
four years are often needed to produce a full crop.