All About Sour Plum Trees

Chinese fruit growers are very enthusiastic about green, crisp sour plums. These early-bearing plums grow in mild-winter locations and are ready for the market — ripe really isn’t the right word to describe them — in March. They are only available for about a month. But in that month Chinese consumers indulge their thirst for a fresh version of suanmeitang, sour plum drink, which is ironically mixed with equal parts of sugar.

Sour plums, fresh, dried, or juiced, are important in Chinese, Japanese, Vietnamese, and Korean cuisine. You may see sour plum drinks in Asian markets, and you may have encountered salty pickled umeboshi in a Japanese restaurant. But are sour plums a potential production plant for North American growers? We will take a look at this and many other interesting questions in this article.

History of the Sour Plum

The sour plum, Prunus mume, originated in southern China along the banks of the Yangtze River. In the wild, it is a mountain plant. It grows at elevations up to 10,200 feet (3100 meters). Blooming in late January and early February, these plums are a source of the earliest floral decorations of the year in much of East Asia. They have tremendous importance in Asian culture,

Sour Plums in Chinese Culture

There are 400 varieties of sour plums grown in China. In stories and in art, Chinese plum blossoms are seen as a late-winter messenger of the arrival of spring. 

Because these plum trees bloom while the weather is still cold, they are termed, along with bamboo and pine, as one of “Winter’s Three Friends. Historians of Chinese art include sour plum blossoms as one of the “four gentlemen” of paintings, counting them blossoms as the symbol of winter. (The orchid is the gentleman of spring, the lotus the gentleman of summer, and the chrysanthemum the gentleman of autumn.) Panels of paintings based on the four seasons usually include one panel of sour plum blossoms.

Sour Plum in Japanese Culture

In North America, we are more familiar with Japanese cherry blossoms, but in Japan, sour plums play an important role in garden design. Japanese formal gardens usually place a plum tree in the northeast corner. In mythology, the plum blossom was thought to “astringe” evil, expelling it with its intense beauty followed by its sour fruit. Eating pickled sour plums (the previously mentioned umeboshi) for breakfast was once thought to ward off evil for the day.

Sour Plum in Vietnamese Culture

The term “Mai, which refers to the beauty of plum blossoms, is a popular name for girls. Two hospitals in Hanoi, two hospitals, Bach Mai and Mai Huong, are named after the healing sour plum blossom.

Sour Plum in Korean Culture

In Korea, sour plums are used to make the first bouquets of spring. Special blossom vases display them. Plum blossoms are also a favorite embellishment for embroidery.

Sour Plum Tree and Fruit Characteristics

It is not hard to recognize a sour plum tree in mid- to late-winter. This 12- to 35-foot (4 to 10 m) tree is covered with flowers of varying shades of pink, white, and red in January and February. 

Leaves appear not long after the blossoms fall. They are 1-1/2 to 3 inches (4 to 8 cm) long and 1 to 2 inches (2.5 to 5 cm) wide, oval with a pointed tip. In mild-winter climates with an early spring, such as Fujian province in China, fruit comes in March and April. In more northerly locations, the harvest may be in June or July. In Japan, sour plum harvest coincides with the annual monsoon called the “plum rain.” 

The leaves and seeds of these trees are toxic. Like other stone fruits, they contain small amounts of cyanides.

Planting Zones

Sour plums can be planted in climates corresponding to USDA Hardiness Zones 6 to 8. They may blossom but not fruit in USDA Hardiness Zone 6, because the young fruit will be killed by later frost. Their range is limited by the fact that they need just 500 to 1300 chilling hours, depending on the variety.

Horticulturalists at Purdue University in the USA are working to develop cold-hardier varieties of the plant that need more chilling hours for northern-state production. Chinese scientists are also developing sour plum trees for production in the colder, damper climates of Manchuria.

Size and Spacing

Sour plums appear naturally in “sparse” forests. They need to be spaced at least 15 to 20 feet (5 or 6 meters) apart. 

Tree Care 

If you want your sour plum tree to thrive, it is important that the area where you plant it receives at least six hours of sunlight per day. The soil should be well-drained and ideally have some compost mixed into it for nutrients.

Pruning

While it’s not recommended, sour plum trees can be pruned. Sour plums are more sensitive to light than other fruit trees and need a lot of water. So if you do decide to trim your tree, make sure that the cut is well-spaced along the branch so that sunlight reaches all parts of the branches.

Harvesting

Sour plums are picked green for making pickles and juice in China. They can be allowed to ripen to a bright yellow with a red blush for harvest in June and July.

Pests and Diseases

American growers of sour plums have dealt with a variety of pest problems:

• Aphids on new growth in the spring.
• Borers in distressed plants.
• Tent caterpillars in the summer. They can kill a tree.
• Spider mites during summer droughts.

Irrigation

These plum trees depend on rainfall, and should only be grown in areas with reliable, year-round rainfall of 35 inches (850 mm) or more.

Common Uses For Sour Plum Fruit

Plums are a versatile, everyday ingredient in East Asian cuisines. If you eat authentic Chinese, Japanese, Korean, or Vietnamese food on a regular basis, you will certainly be served sour plums.

Sour Plum Drinks

Smoked sour plums, called wumei, are turned into a popular Chinese beverage called suanmeitang (literally, “sour plum soup”). The beverage maker smokes green or ripe plums and then boils them. Then the mixture is strained and sweetened with copious amounts of sugar. Even without any added salt, it usually has a slightly salty taste. Suanmeitang is flavored with sweet osmanthus flowers for a chilled beverage.

Korean cooks combine dried flowers they pick in the spring with fresh sour plum fruit to make plum blossom tea, maehwa-cha. This is a beverage made the same way as any loose tea. Pour hot water over chopped fruit and plum petals, allow to steep in a closed teapot (to keep the flavor in the essential oils from evaporating) for 15 minutes, strain, and serve. This tea can be drunk hot or cold.

In Japan, where sour plums don’t mature until May, June, or later, there is a similar beverage drunk cold on hot days.

You can find versions of all of these drinks in Asian groceries in the US and Canada.

Sauces

Have you ever had duck sauce in a Chinese restaurant? There is a similar thick, sweet Chinese sauce made with sour plums, salt, chili, garlic, ginger, vinegar, and sugar. It’s a “plum sauce” known in Chinese as meijang. This is the plum sauce you get with egg rolls and poultry dishes.

Korean cooks use sour plums as a famine food to make “plum syrup,” a substitute for sugar crystals. The cook has to use equal parts of plum juice and sugar, or the mixture will ferment and make plum wine. Either plum syrup or plum wine needs about 100 days to develop flavor. They keep for up to a year.

Sour Plum Blossom Pancakes

Korean cooks sometimes use fresh plum petals to make pancakes, served with honey as a sweetener.

Sour Plum Pickles and Preserves

Chinese chefs pickle unripe sour plums with salt and vinegar to make suan mei zi. “sour plum fruits.” These pickles are intensely salty and sour. There are versions of Chinese pickles that add sugar and herbs. The pickled plums can be dried to last for years.

Umeboshi are served in tiny portions with Japanese food. These slices of sour plum pickle are red because they are pickled with purple shiso leaves. The shiso leaves give umeboshi their distinctive flavor. Japanese sour plum pickles are made from plums at a later stage of ripeness than the sour plums used to make Chinese sour plum pickles.

Umeboshi are sometimes used for rice balls and rolled sushi. There is also a Japanese umeboshi vinegar.

Korean cooks make a sour plum banchan (side dish) called massil-jangajji from dried plums, salt, and tea leaves. It keeps for up to a year.

There is also a pickled sour plum dish called  xí muội or ô mai in Vietnamese cuisine.

Wines

It’s possible to make a wine from sour plums, but most often they are used to flavor rice wine or sake.

Eating Raw

Eating sour plums raw is not recommended.

Canning / Freezing / Drying

The usual method of preserving sour plum fruit is pickling. Hundreds of combinations of sour plums, salt, sugar, vinegar, and herbs can be found in Asian cookbooks.

Health Benefits of Sour Plum Fruit

There are records of sour plum paste used as a medicine in China dating back 3500 years. In the traditional medicine of China, Japan, and Korea, sour plum “soup” was used to stop coughing from colds. It was used to expel parasites. Salty preparations of the fruit were used to stop diarrhea.

One of the most interesting applications of sour plum fruit being explored by scientists as this article is being written is in fighting fatigue after exercise. Expect energy drinks in the near future.

Where Do You Buy Sour Plum Trees?

Sour plum trees are occasionally available in nurseries all over the United States and in British Columbia in Canada You can also check out Nature Hills Nursery for more information.

Where To Buy This Fruit

Every Asian grocery has sour plums. You will find them as beverages, condiments, and pickles.

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