Botanical Overview
A member of the Buckthorn family (Rhamnaceae), the genus Ziziphus has about 40 species
composed of spiny shrubs and trees.
Ziziphus jujuba is cultivated and naturalized in temperate and tropical zones world-wide, most
extensively in Asia, and has over 800 cultivar names.
Description
Form:
A tree which varies from tall and narrow to wide and rounded.
Lifespan:
Jujube trees may be productive for more than 100 years.
Leaf retention:
Deciduous.
Growth rate:
Moderate to rapid.
Mature Size:
30-50' (9-15m) high and 15-30' (4.5-9m) wide, depending on cultivar.
Flowers:
Very small, clustered, greenish-yellow, five relatively large sepals, five tiny petals,
fragrant. Jujubes are divided into morning-opening or afternoon-opening, however this
does not seem to affect fruit set in temperate climates such as the United States.
Bloom:
Spring into summer. The flowers bloom in the same year their buds form.
Self-fruitful:
Most cultivars produce fruit by self-pollination, although the yield can be low without a
second tree. Some cultivars require a second tree nearby, often another cultivar, especially
to produce viable seeds. Ants and wind, rather than bees, seem to do most of the pollination.
Hand pollination may be needed when pollinating insects are absent or lack interest.
In China, cultivars are classified by fruit set temperature requirements: high –
daily average temperature 77°F (25°C) or higher), intermediate – 73.4°F (23°C), and
low – 70°F (21°C or higher).
Low daily average temperatures at the time of flowering can reduce fruit set and productivity
in some cultivars.
Years before fruiting:
Most cultivars flower and fruit in their first year of planting. All will be flowering
in their second year. They become most productive at three to five years.
Fruit:
Thin skin, white flesh, edible, cherry sized (small) to plum sized (very large). If
pollinated, the fruit has a single stone containing two seeds. The skin is green when the
fruit is immature. When edible, the skin turns yellow-green, then acquires red or red-brown
spots, then becomes entirely red-brown at which point the fruit is at the peak of its
flavor. Wrinkles develop after the fruit become fully red-brown, and on some cultivars,
just before the fully red-brown stage.
The flavor depends on cultivar, microclimate, and irrigation. For fresh eating
cultivars, the taste is crisp and sweet-tart, like an apple, between the yellow-green and
red-brown stages; however large fruit should not be harvested until at least half red-brown.
For drying and multipurpose cultivars, when almost fully red-brown, the fruit can change in
flavor to a cross between an apple and a date, and to date-like when fully dried.
Months for fruit to ripen:
2-3. The fruit ripen on the tree a few at a time, over many months. The fruit of fresh eating
cultivars are edible when the skin color changes from green to yellow green or light green.
The best flavor for fresh eating and multipurpose cultivars is when they are half to full
red-brown. Do not allow the fruit to dry on the tree past the full red-brown phase. They lose
flavor and vitamin C quickly after that. The best time to harvest is early morning when the
fruit have moisture and a better flavor. In the afternoon, they are dryer and lose crispness.
Late ripening cultivars need to grow in regions with long, hot summers and their fruit may
not ripen in short-season colder climates.
Storage after harvest:
The fruit do not ripen further if picked when the skin is green, but will continue to ripen
if picked after a change in color to light green or red-brown. Depending on maturity, fresh
jujube can be refrigerated 2 weeks to 2 months. Drying jujubes should be oven dried when
harvested fully red-brown. They can then be refrigerated as long as one year.
Leaves:
Long and narrowly lance-shaped to oval, finely serrated margins, three longitudinal
veins, green, turning yellow in the fall. Some cultivars have naturally curly or cupped
leaves.
Stems:
Branches have a slight zigzag shape with two spines at the base of each leaf. The
spines may be straight or hooked. Jujube has four types of shoots –
primary shoots which grow longer every year;
secondary side branches that wither and die after 2-3 years;
mother-bearing fruiting spurs only one millimeter long on the secondary branches;
and fruit-bearing branchlets 4-8" (10-20cm) long growing from the spurs.
The primary shoot of young trees has smooth, reddish-brown bark.
These trees usually become less thorny with age.
Roots:
Jujube is often grafted onto rootstock which can produce suckers from its lateral roots over
a wide area, even into the yards of neighbors.
Trees should be planted 30' (9m) from the foundation of any structure and 50' (15m) from water
pipes and sewer/septic systems.
The roots of a jujube tree can extend 12-25' (4-8m) deep.
Cultivars of Note:
FRESH EATING cultivars
'Autumn Beauty'
Large fruit, very good spicy-apple flavor, low-medium yield, early season ripening.
Tree height 9-10' (2.7-3m) after 3 years, width about 60% of height, very long thorns.
'Chico'
Medium sized apple-shaped fruit, good flavor, medium yield, early season ripening.
Tree height 11' (3.3m) after 3 years, width about 60% of height, very long thorns.
'GA866'
Medium sized, elongated oval fruit, good flavor, low yield, late season ripening,
not appropriate for short growing season (colder) climates. Tree height 11-12' (3.3-3.7m)
after 3 years, width about 50% of height, short thorns.
'Honeyjar'
Small round fruit, a taste test winner, medium yield, early mid-season ripening.
Tree height 8-10' (2.4-3.0m) after 3 years, width about 50% of height, leaves curl in on
sides, shorter thorns.
'Li'
Large round to oval fruit, variable flavor often below average, medium yield,
mid-season ripening. Tree height 9-10' (2.7-3m) after 3 years, width about 70-85% of
height, very long thorns.
'Maya'
Small football-shaped fruit, a taste test winner, medium yield, early to mid-season
ripening. Tree height 10-11' (3.0-3.3) after 3 years, width about 45-60% of height, short
thorns.
'Sandia'
Medium-size round fruit, excellent flavor even before fully ripe, low yield,
late season ripening. Tree height 8' (2.4m) after 3 years, width about 70% of height,
short thorns.
'Shanxi Li'
Large oval fruit, below average flavor with spongy texture, high yield, mid-season
ripening. Tree height 9-10' (2.7-3m) after 3 years, width about 50-75% of height.
MULTIPURPOSE and DRYING cultivars
'Black Sea'
Oval-shaped fruit, fully brown when ripe, very good fresh eating and dried flavor,
mid-season ripening, a smaller and quite ornamental tree, among the first jujubes
to leaf out, developed in Ukraine.
'Lang'
Medium-large pear-shaped fruit, below average fresh flavor, very good apple-date
flavor for a few days at peak ripeness, declining quickly to mediocre loose textured dried
flavor, medium-high yield, mid-season ripening. Tree height 9-10' (2.7-3m) after 3 years,
width about 60-75% of height, few thorns.
'Sherwood'
Large fruit, elongated oval shape sometimes with pointed end, good fresh eating
flavor, good dried flavor, low yield in first 3-5 years, then medium yield, late season
ripening, not appropriate for short season (colder) climates. Tree height 12' (3.7m) after
3 years, width about 35-50% of height, few thorns.
'Sihong'
Large oval-shaped fruit, good fresh eating flavor, very good dried flavor, fine
wrinkles on dried fruit, low yield in first 3 years, high yield at 5 years, late mid-season
ripening. Tree height 10-11' (3-3.3) after 3 years, width about 65% of height, few thorns.
'Sugarcane'
Medium sized oval fruit, good fresh eating flavor, below average dried flavor,
medium yield, early to mid-season ripening. Tree height 10' (3m) after 3 years, width about
75% of height, thorny.
Wildlife: The flowers attract ants which are the main
pollinators, and the occasional bee or wasp. The fruit attract birds and small mammals such
as raccoons. The bark is generally not eaten by rabbits. Small fruited cultivars may be
stripped by birds unless covered by bird netting.
Toxic / Danger:
Sharp thorns on many cultivars.
Origin: South Asia. Jujube has been cultivated for
more than 7000 years in China.
Cultivation and Uses
USDA hardiness zones:
6-11. Jujubes are more productive in zones 8a and up, but a few short to mid-season ripening
cultivars can grow and fruit well in zone 6a.
Chill hours:
150-400 hours, depending on cultivar.
Heat tolerant: Yes.
Drought tolerant: Yes.
Sun:
Full sun.
Planting:
These trees do not do well in containers because they need to develop an extensive root
system. No soil amendment is necessary when planting. Deep soils are best, although the
tree seems to flourish in most situations. Space each tree 15-30' (4.6-9m) apart
depending on expected mature width.
Soil:
This tree is tolerant of soil types except that the soil must be well draining. They
can tolerate pH 5.1-7.8 (strongly acidic to slightly alkaline). Minor nutritional
deficiencies occur between pH 7.8 to 8.5 (alkaline). It is moderately saline tolerant.
Fertilize:
Fertilize once a year, before flowering, for best fruiting performance, but the tree
can get by without this step.
Water after becoming established:
During fruiting,
deep water or basin irrigate
once a week in sandy loam or every two weeks in clay, accounting for rain. Fruit may suffer
small skin splits with inconsistent water or rain or if irrigated after a brief drought.
Insufficient water results in poor-tasting fruit and fruit drop. If the tree is not
watered during an extended warm season drought, its leaves will turn brown and it will go
dormant; once a rainy season begins, new leaves will sprout.
A need for water is signaled by drooping leaves. Excessively moist soils can lead
to root rot.
Water monthly when not fruiting.
Mulch:
Apply organic mulch inside the drip line, 8" (21cm) away from the trunk, to reduce moisture
loss.
First Year Care:
Do not fertilize the tree in the first year.
Prune:
Flowers and fruit develop on new growth. If fruit are growing too abundantly, it may be
necessary to thin the fruit so those remaining will grow to proper size.
Remove root suckers immediately that are growing below the graft or away from the trunk,
because they are from the wrong tree, often very thorny, and often produce poor-tasting fruit.
When the tree is dormant in winter, remove dead and damaged branches, and remove crossing
and crowded branches from the center of tree.
Pruning every winter improves fruiting. The rule is "one cut stops, two cuts sprout".
After cutting a one-year shoot, cut off a secondary shoot below the cut to force new
growth and flowering. Without the second cut, new growth stops. This technique can be used to
control height.
During the first three years, prune to develop a strong branch scaffold.
Many jujube cultivars can be espaliered to improve fruit accessibility.
Litter:
Fruit drop when not harvested, leaves in fall.
Propagation:
Cuttings are often grafted onto seedling rootstock. Cuttings of new primary shoots taken late
spring to root often develop sufficient roots in two months. Cuttings of woody stems taken
late winter may have a higher rooting percentage but take about three months to produce
sufficient roots. Root suckers may also be used.
Seed is not true to its parents and seed without cross-pollination is often not viable.
Some cultivars of Z. jujuba are vigorous, with fewer thorns and suckers, and should
provide rootstock with fewer problems.
Problems and Pests:
The most common disease of jujubes in China is Witch's Broom caused by an infectious
microorganism.
Fruit splitting is caused by heavy rain or over-irrigation near harvest time.
Birds and small mammals may raid fruit.
Uses: Ornamental, edible fruit eaten fresh, dried,
candied, made into the equivalent of apple butter, made into syrup for sweetening teas and
dishes, and pitted and preserved in liquor for use in cooking.
When fully red-brown and slightly to fully wrinkled, jujube fruit from some cultivars can
substitute for dates in recipes.
Comments
Another common name is Chinese Date. Jujubes are high in vitamin C,
especially when picked as soon as they are fully red-brown and not sun-dried. If you have not
tasted a fresh, fully-ripe jujube, you are missing out on a flavor better than the common
apple.
Indian Jujube or Thai Jujube, formerly known as Ziziphus mauritiana, and
presently treated as a subspecies of Z. jujuba, is grown for fresh eating. It does not
develop a date-like flavor.
Information on Ziziphus jujuba cultivars was derived in part from studies
performed by Shengrui Yao and associates at New Mexico State University.
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.