Irrigation is essential for good vine growth and grape production. Grapes will adapt to low water
but fruitfulness is reduced.
Water must be applied deeply and thoroughly to fill
the root zone with water. Frequency will depend upon
the soil type, the rooting depth of the vines, the depth
of the soil, and the weather. Irrigating every 2 to
3 weeks is usually adequate under good soil conditions
and moderate climate. Grapes may require more frequent
irrigation in very hot climates in inland valleys.
Drip irrigation is an excellent method of watering.
Generally, a fully trellised vine on a hot summer day
in the Central Valley of California will require about
8 to10 gallons of water per day with drip
irrigation. Vines tha t are less vigorous or untrellised
will require 6 to 8 gallons per day. In Southern California,
the rates should be similar to those of Central Valley
climates. In areas along the coast,
and in northern parts of California, the rates will be
Avoid water stress during the period between bloom and
berry softening. Fruit on the vine may succumb to cracking
if the vines are allowed to dry and then wet again. Check
the soil profile to be sure the plants are getting adequate
water but not too much.