The Java plum tree (Syzygium cumini) which has been known as black plum, Malabar plum, jamun, and jambolan, is a tropical evergreen tree prized for its fruit, timber, and beauty.
Java plum trees originated in India. They are also native to Myanmar, Sri Lanka, and the Andaman Islands. This tree can grow up to 100 feet (30 meters) tall, and it can live more than a century. In the tropical regions where it is adapted, it grows so easily that it can become an invasive plant.
USDA scientists introduced Java plums to South Florida in 1911. They are also present in Hawaii. A Java plum is not a tree you can grow where there are frosts every year, but it’s an interesting addition to tropical orchards. And as we will discuss in some detail later, the fruit is not only delicious, it’s medicinal.
Tree / Fruit Characteristics
Java plums are myrtles. They are in the same family as guavas, feijoas, and allspice.
Java plums grow fast. They can reach their full 100-foot height in 40 years. (Java plums in Florida usually only grow to 40 to 50 feet.) The tree usually forks into multiple trunks very near the ground.
Java plums produce dense foliage that blocks tropical sun. At the base of the tree, the bark is dark gray and rough. The bark becomes lighter and smoother higher in the tree.
Java plum wood is water-resistant if it is dried in a kiln. Historically, this made it useful for housings for the motors used to operate wells, and lining sleeper cars in trains. It can be used to make furniture, but it’s hard to work.
Java plum leaves smell like turpentine. They are pink and soft when they are young, maturing to a glossy but leathery dark green with a yellow rib down the middle as they mature. The leaves make good livestock fodder. They are a good source of digestible carbohydrates, magnesium, phosphorus, and vitamin A. The fruit is an excellent source of vitamin C.
Java plum blossoms appear in clusters. The fruit also appears in clusters of 10 to 40 (although sometimes just a few). Their color changes from light green to magenta to deep purple as they ripen. Most Java plum fruit contain a single seed about an inch (25 mm) long, although sometimes fruit can contain as many as four or five seeds or no seeds at all.The flesh of the fruit leaves an astringent, puckery sensation in the mouth, but can be quite sweet.
Java plums are strictly a tropical fruit. The only safe areas to plant them are in USDA Hardiness Zone 11. Even in South Florida, winter cool spells will stunt their growth. Young trees are killed by even light frost, but mature trees may recover from brief exposure to temperatures of freezing or 1 or 2 degrees below.
Java plums are adapted to extremely high rainfall, up to 400 inches (10 meters) a year, but they can also grow in sandy or loamy soils in frost-free mountainous areas. They won’t grow fruit when they are planted at elevations about 2000 feet (600 meters), but mountain Java plums are still useful for timber and shade.
Size and Spacing
Java plums can grow 100 feet (30 meters) tall. They can spread 36 feet (11 meters) across. But the fickleness of the Java plum’s germination process makes proper spacing difficult.
The usual way of propagating Java plums is to scatter seeds in the rainy season. Java plum seeds will germinate in about two weeks. But seedlings do not always bear fruit of the same sweetness as their parents.
Many Java plum growers in India and the Philippines scatter an abundance of seeds, hoping some will sprout at about the right spacing. They will leave three or four times as many young trees as they believe they will need until after they have grafted limbs from high-quality, older trees. About 20 to 30% of grafts take, so they do not remove extra seedlings for several years until the young trees are well established.
Java plum seeds remain viable for only two to three months. If they are not planted within that time, they will never germinate.
Trees are grown 20 feet (6 meters) apart for windbreaks, and 40 feet (12 meters) apart for agricultural production.
Java plums are pollinated by insects. They are an excellent plant for honey producers.
Java plum trees begin to produce at the age of 8 to 10 years. Grafted branches will bear fruit after 4 to 7 years.
Java plums grow tall enough that they do not compete with other plants for shade. Coffee growers using Java o=plums as shade plants will top them for denser growth of foliage.
Young trees are fertilized with compost to ensure vigorous growth. Once a tree becomes old enough to bear fruit, organic fertilizers are applied after flowering and fruiting to avoid excessive growth of foliage.
Java plum trees are topped to create denser foliage for better shade for coffee crops. Otherwise, they are not pruned.
Java plum fruit have to be picked by hand. A single 5-year-old branch can yield 500 fruit. A 100-year-old tree can produce 100,000 fruit. Hobby growers and homeowners planting Java plums for shade are usually overwhelmed by their harvests. The fallen fruit become food for birds, mice, and rats if they are not picked up regularly.
Pests and Diseases
In Florida, some Java plum trees are very susceptible to scale insects. Florida Department of Agriculture inspectors also find algal leaf spot black leaf spot, mushroom root rot, and anthracnose.
Whiteflies are a problem with Java plus in India. Sometimes leaf-eating caterpillars completely denude Java plum trees in India.
Java plum fruit attract civet cats and jackals in India. In Australia, Java plum fruit is a favorite food of the flying fox, a large bat.
Java plums have been grown in Algeria and Israel under intense, regular irrigation. In the US and the Caribbean, they do well on rainfall.
Common Uses For The Fruit
Java plum fruit are almost as dark as Kalamata olives on the outside but as white as guavas or soursops on the inside. They are a unique taste experience for people who have not encountered them in Asia or in frozen form in Indian markets in the USA.
What does this fruit taste like?
Weird Fruit Explorer bit into a Java plum for the first time on camera. “A little astringent, and sweet but not too sweet. It doesn’t taste like poison,” Weird Fruit Explorer said without overwhelming enthusiasm.
Other connoisseurs of Java plums talk about their sweet, sour, peppery, and mouth-drying flavors. Java plum may not be something people want to eat every day, but it’s an interesting occasional treat in jams, jellies, candies, and sorbet.
Most American fans of Java plums mix them with guavas to make sorbets, fruit soups, or conserves. Java plums need additional pectin for jellies and jams to set.
Java plums don’t usually survive the trip from the grower to the store if it takes more than a few hours. But the peel and flesh are edible raw.
Canning / Freezing / Drying
The usual way of preserving Java plum is freezing.
Learn more about cooking with plums at Minnetonka Orchards.
Health Benefits of Java Plums
Nutrition researchers at the Lovely Professional University in Punjab in India have found anti-diabetic, anti-inflammatory, antibacterial, anti-allergenic, liver-protective, and cholesterol-lowering compounds in Java plums. That doesn’t mean that if you eat Java plums that these problems will go away, but including Java plums in your diet is likely to be supportive of recovery from these conditions. But Java plum has been used in diabetes diets for over 135 years.
One of the interesting experiences you may have biting into a fresh Java plum is pain relief. The eugenol found in Java plums (like their close plant relative, the plum tree) is a mild topical anesthetic. Just as you might put oil of cloves on an aching tooth (it’s available in drug stores), you can get relief from pain in the mouth and gums by eating Java plums. But don’t take them as medicine. Just feel free to enjoy them even if you have a toothache.
For more plum heath benefits check out our post on The Health Benefits of Plums.
Where To Buy Java Plums
Most Indian groceries have frozen Java plums, labeled as jamun.
Java Plum Fruit Facts
Some interesting facts about Java plums include:
- In Hindu mythology, Krishna is said to have four symbols of the Java plum on his right foot. The leaves and fruit of the plant are used in ceremonies venerating Ganesha, the elephant-headed god, the patron bankers, intellectuals, authors, and scribes.
- In Maharashtra, the second most heavily populated state in India, Java plum blooms are used to decorate pandas, the canopy over which couples say their wedding vows.
- In parts of India, Java plum wood is used to make plows and push carts.
- In Ayurvedic medicine, Java plum fruit is used to treat diarrhea. It may be included in any formula intended to “dry up a bodily function.
- The seeds, not the fruit, of Java plum are sold in parts of the West Indies as diabetes treatment.
- In many parts of the tropics, people are eager to have Java plums cut down because they produce so much fruit it litters the streets.
Most North American and European fruit growers will only know Java plums as a frozen fruit or sorbet they can sometimes get in Indian restaurants and food stores. But these enormously productive plants make an interesting addition to tropical fruit production.