Fruit Facts from
the
California Rare Fruit Growers, Inc.
Jujube
Ziziphus jujuba Mill.
Rhamnaceae
Common
Names: Jujube, Chinese Date, Tsao.
Related Species: Indian Jujube (Ziziphus mauritiana).
Distant Affinity: Purple Haw (Colubrina texensis), Raisin Tree (Hovenia dulcis).
Origin:
The jujube originated in China where they have been cultivated for more
than 4,000 years and where there are over 400 cultivars. The plants
traveled beyond Asia centuries ago and today are grown to some extent
in Russia, northern Africa, southern Europe, the Middle East and the
southwestern United States. Jujube seedlings, inferior to the Chinese
cultivars, were introduced into Europe at the beginning of the
Christian era and carried to the U. S. in 1837. It wasn't until 1908
that improved Chinese selections were introduced by the USDA.
Adaptation:
The jujube can withstand a wide range of temperatures; virtually no
temperature seems to be too high in summertime. Winter dormancy allows
it to withstand temperatures to about -28° F, yet it requires only
a small amount of winter chill in order for it to set fruit. The plant
revels in summer sun and heat, with the lack of either limiting fruit
production more than winter cold. Yet jujubes have fruited in the Puget
Sound and low Cascade regions of Washington State as well as in
Pennsylvania. Fruiting of some cultivars has also been reported in
northern Florida.The Indian jujube, which is more sensitive to frost,
is grown in Florida, but the fruit is considered inferior. Jujube trees
are not particularly suitable for container culture, but can be grown
in this manner in a large container.
Description
Growth Habit:
The jujube is a small, deciduous tree, growing to 40 feet tall in
Florida, but smaller in size in California. The naturally drooping tree
is graceful, ornamental and often thorny with branches growing in a
zig-zag pattern. The wood is very hard and strong. Jujube cultivars
vary in size and conformation, with some being very narrow in habit and
others being more widespread. One cultivar, the So, seems to be fairly
dwarfing in habit. After 30 years of growth in an average site, trees
can be 30 feet tall with a crown diameter of up to 15 feet. Plants send
up suckers (often with intimidating spines) from their roots, and these
suckers can appear many feet from the mother plant. Currently, these
root suckers must be controlled by mowing or hoeing.
Foliage:
The small, ovate or oval leaves are 1-2 inches long and a shiny bright
green. In the autumn, the leaves turn bright yellow before falling.
There are usually two spines at the base of each leaf. Some spines may
be hooked while others are long daggers. Virtually thornless cultivars
are known. As the growing season commences, each node of a woody branch
produces one to ten branchlets. Most of these are deciduous, falling
from the plant in autumn.
Flowers:
The inconspicuous, 1/5 inch diameter, white to greenish-yellow flowers
are somewhat fragrant and produced in large numbers in the leaf axils.
The flowering period extends over several months from late spring into
summer. However, individual flowers are receptive to pollen for only
one day or less. Pollination needs of the jujube are not clearly
defined, but appear to be done by ants or other insects and possibly by
the wind. Most jujube cultivars produce fruit without
cross-pollination. The jujube is well protected from late spring frosts
by delayed
budding until all chance of cold weather has passed.
Fruit:
The fruit is a drupe, varying from round to elongate and from
cherry-size to plum-size depending on cultivar. It has a thin, edible
skin surrounding whitish flesh of sweet, agreeable flavor. The single
hard stone contains two seeds. The immature fruit is green in color,
but as it ripens it goes through a yellow-green stage with
mahogany-colored spots appearing on the skin as the fruit ripens
further. The fully mature fruit is entirely red. Shortly after becoming
fully red, the fruit begins to soften and wrinkle. The fruit can be
eaten after it becomes wrinkled, but most people prefer them during the
interval between the yellow-green stage and the full red stage. At this
stage the flesh is crisp and sweet, reminiscent of an apple. Under dry
conditions jujubes lose moisture, shrivel and become spongy inside.
Tests in Russia indicate a very high vitamin C content. The fruit has
been used medicinally for millennia by many cultures. One of its most
popular uses is as a tea for sore throat.
Culture
Location:
Jujubes should be given a warm, sunny location, but are otherwise
relatively undemanding. Given adequate heat and sun, the trees will
thrive without any special care. They should not be planted in the
shade of other trees.
Soils:
Jujubes tolerate many types of soils, but prefer a sandy, well-drained
soils and do less well in heavy, poorly drained soil. They are able to
grow in soils with high salinity or high alkalinity.
Irrigation:
One of the outstanding qualities of the jujube tree are its tolerance
of drought conditions. Regular watering, though, is important to assure
a quality fruit crop.
Fertilization:
Fertilizer requirements have not been studied, but jujubes appear to do
well with little or no fertilization. Light broadcast applications of a
balanced fertilizer such as 8-8-8 NPK at two-month intervals during the
growing season would probably speed growth. Do not fertilize until the
newly planted tree has several months to get established.
Pruning:
Unpruned trees produce as well as trees that have been pruned.
Extensive winter pruning, however, will keep the plants in better
health and produce more easily obtainable fruit.
Propagation:
Most Chinese cultivars in the U.S. are grafted or budded onto a thorny
rootstalk which produces many suckers from the roots. There is evidence
that jujube cultivars will root on hard or soft wood cuttings. However,
successes have been limited to date with this process of plant
reproduction. Jujubes also can be propagated from seed, although they
do not come true. Most jujube cultivars produce fruit without
cross-pollination, but seeds from such self-pollination are usually not
viable (such as from the Li or Lang cultivars)
Jujubes should be
set out 10 to 15 feet apart since they require high light intensities
for good production. Upon setting out new, bare root trees, top the
plant to 3 or 4 feet and remove all side branches to leave only a whip.
New, stronger branches will emerge from each bud just below the point
where the old branches were pruned.
Pests and diseases:
The Chinese jujube appears to have no serious disease, insect, or
nematode pests in the U.S., hence, no spraying is necessary. Only the
pocket gopher has shown a liking for the roots. One disease, witches
broom, is prevalent in China and Korea and could be destructive to a
new industry if allowed to enter into non-endemic areas.
Harvest:
The crop ripens non-simultaneously, and fruit can be picked for several
weeks from a single tree. If picked green, jujubes will not ripen. Ripe
fruits may be stored at room temperature for about a week.The fruit may
be eaten fresh, dried or candied. Fresh fruit is much prized by certain
cultures and is easily sold in Chinese, Korean, Vietnamese, and Indian
markets. Tree dried fruit stores indefinitely and may have good
marketing potential as it dries on the tree without the use of a sulfur
preservative.
Selected Recipes
Jujube Cake
1 cup sugar
1/2 cup butter
2 cups dried, minced jujube
1 cup water
Bring these to a boil then set aside to cool
2 cups wheat flour
1 teaspoonful soda
1/2 teaspoonful salt
Sift these together then add to the above mixture. Bake at 325° F
Candied Jujubes
Wash
about 3 pounds dried jujubes; drain and prick each several times with a
fork. In a kettle bring to a boil 5 cups water, 5-1/2 cups sugar, and 1
tablespoon corn starch. Add the jujubes and simmer, uncovered, stirring
occasionally, for 30 minutes. Cool, cover, and chill overnight.
The
next day bring syrup and jujubes to a boil and simmer, uncovered, 30
minutes. With a slotted spoon lift jujubes from syrup and place
slightly apart on rimmed pans. Dry in oven, or in sun for about 2 to 3
days. Check fruit frequently and turn fruit occasionally until the
jujubes are like the dates ones sees in the market.
Jujube Syrup
Boil
syrup remaining from the Candied Jujubes, uncovered, until reduced to
about 2 cups. Use over pancakes and waffles. Store in the refrigerator.
Other uses:
Substitute the dried jujube wherever recipes call for raisins or dates.
Dried jujubes are a wonderful snack that can be prepared without the
use of any preservative as is so commonly needed for other dried fruits.
Cultivars
Li
and Lang are the two most commonly available cultivars and were from
the original introductions by Frank Meyer to the Plant Introduction
Station at Chico, California. The following is a list of currently
propagated cultivars, based on the fruit ripening times in southern
California. As interest increases, new cultivars will be brought out of
China and Russia.
Early Ripening
Li
Large, round fruit up to 3 ounces in mid-August. May be picked at the
yellow-green stage. Tree is many-branched, yet narrow and upright. Best
eaten fresh. Best first tree to have.
Mid Season
Ed Hegard
Very similar to the Lang and Thornless.
GA-866
An outstandingly sweet selection out of the Chico Research program. Large, elongated fruit.
Jin
An excellent elongated fruit. Very chewy when allowed to dry on the tree.
Globe
A new, Chinese introduction.
Honey Jar
Another new, Chinese introduction.
Lang
Large, pear-shaped fruit which must be fully colored to be best eating.
This fruit is best to let dry on the tree. Tree is upright and
virtually spineless.
Redlands #4
Collected at an old homestead in Redlands, California. Very large, sweet, round fruit.
So
A tree of most beautiful shape. At each node of the stem the branch
decides to go off in a new direction. Hence, a very zig-zag branching
pattern which casts a beautiful shadow in the wintertime. Tree is
somewhat dwarfed.
Sugar Cane
Small to medium fruit which can be round to elongated. Extremely sweet
fruit but on a very spiny plant. The fruit is worth the spines!
Thornless
Just as the name implies. Very few, if any spines occur. A fruit very similar to the Lang.
Late Season
Admiral Wilkes
Collected on a South Seas expedition in the 1840's and planted on the
Capitol grounds in Washington, D.C. Elongated fruit which has been the
very last to ripen, generally in mid to late November.
Chico (GI 7-62)
Fruit is round but flattened on the bottom. Looks like small apples. Excellent either fresh or dried.
GI-1183
Another cultivar from the Chico program. Large, sweet fruit.
Sherwood
A seedling plant from Louisiana. The fruit is very dense and sweet.
Tree is very narrow and upright with leaves that are weeping in habit.
Silverhill
An elongated fruit which has cropped well even in northern Florida. Virtually spineless.
Tigerstooth
Very similar to Silverhill.
Topekal
From eastern Kansas and an excellent, late cropping fruit.
Further Reading
Reich, Lee. Uncommon Fruits Worthy of Attention. Reading, Mass., Addison-Wesley, 1991. pp 139-146.
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© Copyright 1996-2001, California Rare Fruit Growers, Inc.
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