Chinese Plum (Prunus salicina)

Chinese plum is native to China but is also grown in fruit orchards in Japan, Korea, Vietnam, Australia, and the United States. A drupe is produced as the fruit and can be eaten raw. Different varieties of the Prunus salicina are cultivated in China, with some also being hybrid species. Many of the fresh plums sold in North America are cultivars of chinese plum.

I. Appearance and Characteristics

Prunus salicina (syn. Prunus triflora or Prunus thibetica), commonly called the Japanese plum or Chinese plum, is a small deciduous tree native to China, Taiwan and Southeast Asia. It is an introduced species in Korea, Japan, Israel, the United States, and Australia.

Prunus salicina should not be confused with Prunus mume, a related species also commonly called Chinese plum or Japanese plum. Prunus japonica is also another tree that is a separate species despite having a Latin name similar to Prunus salicina’s common name.

Some names for this plant, in addition to Japanese or Chinese plum, are Willow-leaf cherry, Asian Plum, in English, Ameixa or Ameixa-japonesa in Portuguese, 李 lǐ in Mandarin and Japanskt plommon in Swedish.

The generic name, Prunus, comes from the Greek Prunum, meaning plum. The specific epithet, salicina, is derived from the Latin word for willow.

Prunus salicina grows up to 9–12 metres (30–39 ft) tall, and its branches are purplish brown to reddish brown and its lateral shoots are yellowish red.
The leaves are 6–12 cm long and 2.5–5 cm broad, with scalloped margins, which when young is often mixed with simple gland-tipped teeth. The leaves’ shape tend to be oblong, though it sometimes varies slightly more obovate (broader above the middle), narrowly elliptic, or in rare cases being slightly ovate (broader half below the middle). The base of the leaf is wedge-shaped, and its apex ranges from acute (pointed) to caudate (having a slender short tail). The upper side of the leaf is dark green and lustrous, and have 6 or 7 secondary veins on either side of midvein, not extending to leaf margin.

The winter buds of the Prunus salicina are purplish red, and are occasionally hairy at scale margins, though this is rare. The flowers are produced in early spring, around April, each about 2 cm in diameter with five white petals, and come in groups of 3. The pedicel is 1–1.5 cm, and its sepals are oblong-ovate and about 5mm, hairless on the outside, with loosely serrated margins. The sepal’s apex is acute to obtuse. The petals of the flower are white, oblong-obovate, with a wedge-shaped base and a jagged margin near the apex. The ovary is hairless and the stigma disc-shaped.

The fruit is a drupe, 4–7 cm in diameter with yellow-pink flesh. The skin can be yellow, red, or sometimes green or purple, and has a powdery coating. The shape of the drupe is spherical, egg-shaped, or conical, and it is 3.5–5 cm in diameter, though it can reach 7 cm in diameter in horticultural forms. They fruit from July to August. When fully ripe it can be eaten raw. In comparison to the Prunus domestica, the Prunus salicina, fruit has a higher flavor and aroma, better texture, more color, bigger size, and good nutritional values.

The pit of the Prunus salicina is ovoid (egg-shaped) to oblong, and wrinkled.

As with other stone fruits, the pit and leaves are poisonous to humans, as they contain amydalin, which breaks down to hydrogen cyanide. While poisoning from unintentional ingestion of a few pits is unlikely, it recommended to avoid ingestion, and to never consume crushed up pits.

The Japanese plum, like other Prunus fruit tree species, is mostly self-incompatible and requires cross pollination to ensure fruit set because this genus is unable to bear fruit parthenocarpically. Several cultivars or varieties have however been identified with self-compatibility.

II. How to Grow and Care

Sunlight

Chinese plum likes sunshine. As a fruit tree, ample sunlight for photosynthesis is necessary for its growth and to provide sufficient nutrition to develop fruit. It should be planted in a spot that ensures it can receive at least 6 hours of sunlight, and ideally no less than 8 hours of sunlight.

Temperature

Chinese plum is fairly good at surviving in low temperatures. The temperature it can tolerate ranges from -22 ℃ to 42 ℃. It is also not very picky when it comes to water. It does not need a lot of water and is resistant to both drought and flood.

Watering

Originating from a region with distinct wet and dry seasons, Chinese plum has adapted to manage periods of scarce water, showcasing moderate drought tolerance. Its watering needs align with its resilience, requiring moisture replenishment once every two weeks. In its natural habitat, Chinese plum thrives in conditions where it can experience fluctuations in water availability. Typically grown outdoors due to its size and growth habits, Chinese plum benefits greatly during the growing season when rain patterns mimic its native climate’s rhythm.

Soil

When planting chinese plum, you should select a sandy loam soil or loam that is thick, rich in organic matter, and with a slight to medium alkaline pH of 7-8.5. Avoid planting it in a place where salt and alkalis are concentrated. Additionally, make sure that the soil is moist but drains well. It is best not to grow chinese plum in clay soil.

Fertilizing

To optimize chinese plum’s growth, use balanced nutrition fertilizers rich in nitrogen, phosphorus, and potassium. Begin with a spring application as new growth emerges, and continue with regular feedings every 4-6 weeks during the growing season. Apply according to product guidelines, emphasizing caution to avoid root burn. Fertilization supports chinese plum’s vigor, flowering, and fruit production. Reduce frequency in autumn to prepare for dormancy. Seasonal adjustments and precise dosing are key for the robust health of chinese plum.

Pruning

Chinese plum sprouts on branches that have strong budding capabilities. However, the branches can easily become overcrowded and need frequent pruning to maintain the shape, air circulation, and light exposure within the tree. This also helps to prevent pests and diseases while at the same time helping the leaves receive more sunlight.

Chinese plum can generate a large amount of fruit without any artificial pollination. Because chinese plum can produce a large number of flowers with a high yield of fruit, to maintain its growth and the quality of fruit, it is recommended that some flowers and fruit be removed to concentrate the nutrients for the remaining fruit. As a result, there will not be a large amount of fruit, but those left will be of higher quality and have an improved flavor.

Propagation

Chinese plum can be propagated through sowing, which involves planting seeds. For successful germination, it’s essential to use fresh seeds and provide a well-draining soil mixture. Pre-treatment of seeds can enhance germination rates. Ensure the soil is consistently moist but not waterlogged. Once seedlings have developed, they should be carefully transplanted to individual pots and gradually acclimatized to outdoor conditions before planting in their final location.

Transplanting

The prime window for relocating chinese plum is as winter wanes into the cusp of spring freshness, guaranteeing robust root establishment. Choose a sun-kissed spot with well-draining soil. Transplant with care to avoid stressing the delicate roots.

III. Uses and Benefits

• Medicinal uses

The fruits are also used in Traditional Chinese medicine, to enhance immunity against infectious agents and to treat cancers. Japanese plums cv. Crimson Globe may be taken as a source of antioxidants with a potential to counteract oxidation.

Prunus salicina fruit may contain immunostimulatory (stimulating the immune system by inducing activation or increasing activity) components that potentially may be useful in human and veterinary medicine. Compared to other fruits, Japanese plums, include a reasonable source of fiber and proper source of bioactive compounds (such as vitamin C and phenolic composition). Their phenolic composition positively correlates to their antioxidant properties.

A study evaluating ethanol extracts from 400 herbs found that the Japanese plum was the most effective Glucosyltransferase (GTF) inhibitor and showed the highest antibacterial activity. There has been research into whether the fruit of the Japanese plum has cancer-protective effects because of its antioxidant properties, but as of 2023, it is unclear what role antioxidants in general, play in cancer protection and treatment.

• Culinary uses

Since Prunus salicina Linn. fruit has a short-shelf life (3–4 days) under room temperature as well as cold storage (1–2 weeks), it is often prepared into jams, jellies, wine, and other beverages. Black pepper, coriander, cumin, clove, black cardamom, saffron, nutmeg, cinnamon, poppy seed, ginger, woodfordia, asparagus, withania, adhatoda, and rosemary have been reported to be used in preparing aromatized plum wine. The Santa Rosa plum cultivar produces the best quality wine, in comparison Methley, and Green Gage.

In China, candied fruits are also sold preserved, flavoured with sugar, salt, and liquorice. A study on foraging in the Gongba Valley (Zhouqu county in Gansu, China) identified Prunus salicina as one of the most commonly eaten wild fruits. Liquor made from Prunus salicina fruit is mixed with Prunus mume liquor, and oolong tea liquor to make a Japanese-style plum liquor, wumeijiu (smoked plum liquor), in Taiwan.

In Japan, while it is less commonly eaten than closely related Prunus mume, it is pickled and colored in a similar manner. Especially in Eastern Japan, many summer festivals sell pickled fruits covered in mizuame candy called anzuame (apricot candy, as apricots were traditionally used for the recipe).

In both countries, it is also used half ripe as a flavouring in a liqueur called sumomo shu (すもも酒) in Japanese.

IV. Harvesting and Storage

The fruits of chinese plum usually ripen in the early fall and can be picked for eating. If the fruit needs to be stored or transported a long distance, it is better to harvest the fruit before it softens, such as during the late summer or early fall. Note that fruit should be handled gently and, ideally, and the twig should remain on the fruit.