Related Species: Breadfruit (Artocarpus altilis), Breadnut (A. altilis 'Seminifera'), Champedak (A. integer), Lakoocha (A. lakoocha), Marang (A. odoratissimus). Distant affinity: Figs (Ficus spp.), Mulberries (Morus spp.), African Breadfruit (Treculia african).
Origin: The jackfruit is believed indigenous to the rain forests of the Western Ghats of India. It spread early on to other parts of India, southeast Asia, the East Indies and ultimately the Philippines. It is often planted in central and eastern Africa and is fairly popular in Brazil and Surinam.
Adaptation: Jackfruit is adapted to humid tropical and near-tropical climates. Mature trees have survived temperatures of about 27° F in southern Florida, but these were frozen to large limbs. Young trees are likely to be killed at temperatures below 32° F. Unlike its relative, the breadfruit, the jackfruit is not injured by cool weather several degrees above freezing. There are only a dozen or so bearing jackfruit trees today in southern Florida, and these are valued mainly as curiosities. There are also several trees planted in the Asian exhibit at the San Diego Zoo. What they will do or how high they will grow remains a question. The tree is too large to make a suitable container-grown plant.
Foliage: The leaves are oblong, oval, or elliptic in form, 4 to 6 inches in length, leathery, glossy, and deep green in color. Juvenile leaves are lobed.
Flowers: Male and female flowers are borne in separate flower-heads. Male flower-heads are on new wood among the leaves or above the female. They are swollen, oblong, from an inch to four inches long and up to an inch wide at the widest part. They are pale green at first, then darken. When mature the head is covered with yellow pollen that falls rapidly after flowering. The female heads appear on short, stout twigs that emerge from the trunk and large branches, or even from the soil-covered base of very old trees. They look like the male heads but without pollen, and soon begins to swell. The stalks of both male and female flower-heads are encircled by a small green ring.
Fruit: Jackfruit is the largest tree-borne fruit in the world, reaching 80 pounds in weight and up to 36 inches long and 20 inches in diameter. The exterior of the compound fruit is green or yellow when ripe. The interior consists of large edible bulbs of yellow, banana-flavored flesh that encloses a smooth, oval, light-brown seed. The seed is 3/4 to 1-1/2 inches long and 1/2 to 3/4 inches thick and is white and crisp within. There may be 100 or up to 500 seeds in a single fruit, which are viable for no more than three or four days. When fully ripe, the unopened jackfruit emits a strong disagreeable odor, resembling that of decayed onions, while the pulp of the opened fruit smells of pineapple and banana.
There are two main varieties. In one, the fruits have small, fibrous, soft, mushy, but very sweet carpels with a texture somewhat akin to a raw oysters. The other variety is crisp and almost crunchy though not quite as sweet. This form is the more important commercially and is more palatable to western tastes.
Soil: The jackfruit flourishes in rich, deep soil of medium or open texture. Planting on top of an old compost heap would be ideal. The faster one can force a tropical plant to grow, the better the chance of keeping it alive. The tree needs the best drainage and cannot tolerate "wet feet".
Irrigation: The tree will not tolerate drought. Water frequently during warm months and warm periods in cooler months. Less water is necessary during colder weather.
Fertilization: The jackfruit's requirements are not known, but frequent, weak solutions of all-purpose fertilizer will speed the plant's growth without causing burn. In the regions where it is commonly grown, it succeeds without much care from man, the sole necessity being abundant moisture.
Frost protection: Although mature jackfruit trees will take several degrees of frost, it is prudent to provide young plants with overhead protection if possible and plant them on the south side of a wall or building. Small plants should be given complete protection with a covering on cold nights and even a light bulb if possible.
Propagation:Propagation is usually by seeds, which can be kept no longer than a month before planting. Germination requires 3 to 8 weeks. The seedlings should be moved when no more than 4 leaves have appeared. A more advanced seedling, with its long and delicate tap root is very difficult to transplant successfully. Cutting-grown plants and grafted seedlings are possible. Air-layering is common in India.
Pruning: Little or no pruning is required other than to remove any dead branches from the interior of the tree, so that sufficient light is obtained for the developing fruit.
Pests and diseases: A variety of pests and diseases afflict the jackfruit tree and fruit regions where it is commonly grown. In California the white fly is a minor pest.
Harvest: Jackfruits mature 3 to 8 months from flowering. When mature, there is usually a change of fruit color from light green to yellow-brown. Spines, closely spaced, yield to moderate pressure, and there is a dull, hollow sound when the fruit is tapped. After ripening, they turn brown and deteriorate rather quickly. Cold storage trials indicate that ripe fruits can be kept for 3 to 6 weeks at 52° to 55° F and relative humidity of 85% to 95%. Immature fruit is boiled, fried, or roasted. Chunks are cooked in lightly salted water until tender and then served. The only handicap is copious gummy latex which accumulates on utensils and hands unless they are first rubbed with cooking oil. The seeds can also be boiled or roasted and eaten similar to chestnuts. In Southeast Asia dried slices of unripe jackfruit are sold in the markets. The ripe bulbs, fermented and then distilled, produce a potent liquor.
Related Specie: 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.
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
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.