Botanical Overview
A member of the Grape family (Vitaceae), the Vitis genus contains 79 species of
vining plants, many of them native to North America. Vitis vinifera, the European grape, is
the predominate commercially grown grape for fresh eating, wine, and drying for raisins. This
species grows best below 4500 feet elevation. American grape species are usually chosen for
elevations above 4500 feet.
Description
Form:
Woody climbing vine.
Lifespan:
Productive 50-100 years.
Leaf retention:
Deciduous.
Growth rate:
Moderate to rapid.
Mature Size:
20-25' (6-7.6m) long.
Flowers:
Tiny, greenish, in clusters.
Bloom:
Spring or summer, depending on climate and cultivar.
Self-fruitful:
Yes.
Years before fruiting:
2-4.
Fruit:
Each flower produces a single grape. The grapes are produced on vines growing from one year
old canes.
Months for fruit to ripen:
3-4, depending on weather. Grapes are ripe when they have changed color, when they are full
size, when a whitish coating has covered them, when they have slightly softened, and when
they taste ripe. They do not ripen further after harvest.
Storage after harvest:
Fully mature grapes, in a perforated plastic bag, will last 2 weeks in a refrigerator.
Leaves:
Green, large, usually five lobes.
Stems:
No thorns. Climbs using tendrils.
Roots:
Vines are usually grafted onto the rootstock of North American grape species that are far
more pest resistant. The roots grow mostly in the top 3' (1m) of soil but can extend
15' (4.5m) deep.
Cultivars of Note:
'Black Monukka Seedless' purplish black, large,
sweet.
'Flame Seedless' light red, medium size, sweet.
'Thompson Seedless' pale green, size depends on
thinning, very sweet.
Wildlife:
The flowers attract pollinating insects. The fruit attracts birds.
Toxic / Danger:
No.
Origin:
Middle East.
Cultivation and Uses
USDA hardiness zones:
'Black Monukka Seedless' 6-10, 'Flame Seedless' 7-10, 'Thompson Seedless' 7-9.
Chill hours:
100 hours for 'Black Monukka Seedless', 'Flame Seedless' and 'Thompson Seedless'. Always choose
grape cultivars needing less than 200 chill hours and which tolerate high temperatures.
Heat tolerant:
Yes.
Drought tolerant:
Yes.
Sun:
Full sun.
Planting:
Locate grape vines in full sun away from any low area where cold air can collect. Set up a
support system such as a trellis or fence before putting the plant in the ground. Grapes are
often planted on south-facing hillsides that shed both cold air and excess water. They can
be grown in 15-20 gallon (55-75 liter) containers.
Soil:
Grape vines need well draining, deep, fertile, soil and do best in pH 5.6-6.5 (slightly acidic)
soil but can tolerate a wider pH range.
Fertilize:
Grapes need less fertilizer than most crops. Soil testing is best to determine if it is
necessary. Some growers fertilize as little as once every three years. Nitrogen is the
component most often needed, which can be supplied using composted manure.
Water after becoming established:
Deep water monthly, except every two weeks for fruit
production or during the second year after planting.
Mulch:
Cover the root area with organic mulch when freezing temperatures are predicted.
First Year Care:
Do not fertilize. Water regularly, but do not over water, to establish a strong root system.
Prune:
After leaf drop, and before new buds emerge, cut off canes that have just fruited – these
will be two years old. Also remove unsuitable and excess canes so that only two to four of the
strongest one-year-old canes remain. Some cultivars, like Thompson Seedless, should have the
number of small grapes on the vine reduced to produce larger fruit.
Litter:
Leaf drop in fall. Grape litter if not harvested regularly.
Propagation:
Cuttings grafted on special rootstock.
Pests:
Western Grapeleaf Skeletonizer moth: Harrisina metallica. The larvae, which have five stages,
are cream colored in the first two stages, brown in the third, and yellow with two purple and
several black rings in the final stages.
They eat grape leaves from the underside in the first three stages, then appear on the top
of the leaf in the late fourth and fifth stages.
They have black, poisonous tufts of hair which cause skin irritation.
The larvae can destroy grape plants and should be caught and removed early.
The day-flying moths are entirely black.
They lay their eggs in clusters on the undersides of grape leaves.
They can have as many as three broods a year.
Bacillus thuringiensis is a recommended treatment, but is only effective against young
larvae, and should be applied when eggs or single-colored larva are seen.
Larva at the striped stages require a chemical treatment.
Uses:
Edible grapes for fresh eating, raisins, and wine making. As an ornamental plant these vines
can be grown on a privacy screen trellis or arbor roof.
Do you have additional information or a different experience for these plants that you would
like to share? Email info@GardenOracle.com. All contributions are welcome and appreciated.