American Wild Plum
I ruined many white t-shirts harvesting wild plums when I was a boy. I would roll up the front of my t-shirt forming a bowl-shaped container like a kangaroo’s pouch to carry the small plums home. This would both irritate and thrill my grandmother. She loved to make her delicious wild plum jelly, but not the stain removal involved later. In late summer, my friends and I would find a large thicket of wild plum trees. We would pick and eat until we had our fill. Then after getting numerous chigger bites, we would carry shirt-loads of fruit back to my house. My grandmother would then start pitting the plums, cooking them, steaming the canning jars, and filling them with jelly.
This large native shrub or small tree is a short-lived member of the Rosacea family like peaches and cherries. It is commonly known as the wild plum, American plum, goose plum, august plum, hog plum, hedge plum, and Marshall’s large yellow sweet plum. Wild plums are deciduous multi-stemmed shrubs or small single-trunk trees with a low, broad, spreading crown. These plum trees typically grow 15 to 25 feet in height with a 15- to 25-feet spread. The national champion in Fairfax County, Virginia, is 18-feet tall with an 18-foot spread and the trunk is 3.8 feet in diameter. Their finely serrated leaves are alternately arranged, oval to oblong, and 2 to 4 inches long by 1 to 2 inches wide. The leaves have a wrinkled, dark green appearance on top and are smooth with pale green coloration underneath. Their leaves have pointed tips and narrow bases. Leaves turn pale yellow to electric red in the fall. Their slender twigs are orange-brown to dark reddish-brown in color and are marked with tiny raised dots or lenticels. Some twigs are modified into large thorns up to 3 inches in length. The thin spreading branches are covered in a rough reddish-brown bark. The bark on the trunk starts out a smooth, shiny reddish-brown then turns grey to greyish-black with a scaly, rough texture as it ages.
The small, white five-petaled flowers of the wild plum appear in mid-spring before the leaves emerge. The showy, 1-inch flowers have a strong sweet fragrance that some people find offensive. Their flowers are arranged in clusters of 2 to 5 flowers called umbels. The small, round, 1-inch edible fruit appears in late summer to early fall. Technically, the fruit are drupes or stone fruits like peaches and mangos. When ripe, the reddish-yellow to purple fruit are covered in a powdery white bloom or yeast. They have a tough skin and a bright yellow tart-flavored pulp. Each plum has a large slightly flattened stone or pit with two ridges along each side. Inside each pit is a solitary seed.
The roots are shallow and widely spread beyond the drip line of each tree. Suckers are continually sent up from the roots forming dense thickets or colonies of trees if left undisturbed.
Site Selection/Range/General Culture
These native trees have adapted to a wide variety of habitats and soil types. But, they prefer full sun to partial shade and moist, well-drained, course to medium soils with a pH of 5.5 to 7.5. They range widely from zone 3 in central Canada to Arkansas, on southward to zone 8 in the panhandle of Florida, eastward to South Carolina and back northward to eastern Canada. Wild plums can be found growing along roadsides, by railways, alongside fencerows, in swamps, on rocky hillsides, in the moist edges of forests, and in abandoned fields.
Wild plums require little maintenance other than removing the numerous suckers that appear around the trees. They will grow up 2 feet per year when given the right conditions. They don’t like wet feet, fine soils, drought, forest fires, or too much shade. They produce more fruit when given at least 12 hours of bright sun but will tolerate as little as 30% shade. These fast-growing trees need lots of lateral space so plant them 8 to 10 feet from other plants in the landscape or on 18-foot centers when grown in an orchard.
Wild plums are drought tolerant and seldom need extra watering. They perform the best when kept on the dry side. When watering wild plum trees, water thoroughly and then wait until the top 2 inches of the soil is dry before watering again. At the other end of the spectrum, they will tolerate up to 3 days of flooding but if left wet they will get root rot.
Fertilization needs can vary with soil type and age of the tree. Plum trees are moderate feeders. Give young non-bearing or newly planted trees an application of 10-10-10 dry chemical fertilizer in early spring before their leaves appear. Spread 1 cup of 10-10-10 evenly in a 3-feet diameter area around the tree, but be careful not to place any fertilizer near the trunk of the tree. Make a second fertilizer application in mid-May through mid-July. This time using ½ cup of ammonium nitrate (33-0-0) broadcast evenly in a 3-feet diameter area around the tree.
The second year after the tree is established, fertilize the tree once in March and again in early August. The first application should be 1 cup of 10-10-10 per year of the tree’s age up to 12 cups for mature trees. The second application should be made no later than the second week of August otherwise you risk compromising the tree’s cold hardiness during the winter. This second application should be 1 cup of ammonium nitrate (33-0-0) per tree per year of the tree’s age up to 5 cups for mature trees. A rule of thumb is if an established tree has dark green leaves and it is producing 12 to 15 inches of shoot growth per year then it is receiving adequate fertilization. But, yearly soil tests are still recommended to monitor the fertilization level.
Pruning & Training
Wild American plums bear fruit all along their branches and will withstand heavy pruning. For the best fruit production, prune your trees to a short single trunk form. Let the trees go without much pruning for the first three years after planting, only do some light shaping. After 3 years of getting established, rejuvenate your trees by pruning out a few older branches every other year. Try to finish any pruning by the end of July so as not to disturb flower or fruit bud production for the next year. It will also be necessary to pull or dig up the many suckers or root sprouts these plants produce each year. In an orchard situation, wild plum trees are top-sheared to keep them short enough to be conveniently picked thus limiting labor costs.
Wild plums depend on cross-pollination from other wild plums and honeybees are the primary pollinators. Wild plums are also good pollinizers for hybrid plum trees that bloom about the same time. Most wild plum trees do not form viable seeds until their 4th or 5th year.
If large numbers of plants are needed, then seeds should be your choice of propagation. The downside of propagating by seed is the irregular variation of fruit quality and other characteristics. Whereas, using softwood cuttings or root sprouts, produces a truer duplication of the parent plant. When propagating by seed, harvest fully ripe fruit in late August from trees with the best tasting fruit and remove the pulp from around the pits. Air-dry the pits for several days. Then, use a pair of vise-grips to crack the pits and remove the seeds. As a viability test, place the seeds in a glass of water. The seeds that sink to the bottom are the good viable seeds. Evenly space the viable seeds on a moist paper towel or on toilet paper. Loosely roll up the paper and put the roll in a plastic baggie. Refrigerate the roll of seeds for about 2 to 3 months and then check for germination. Plant the germinated seeds individually into small plastic cups, 4-inch pots or 36-cell plug flats. Seedlings will attain suitable size to plant-up into 3-gallon pots or in the field or the landscape in 1 to 2 years. It will be another 2 to 3 years before you will harvest any fruit from your young trees. Another less effective method is to sow the seeds directly in the field in early fall thus the seeds can have 3 to 6 months of cold stratification to break dormancy. The seedlings produced by either method will not necessarily have the same fruit quality or growth characteristics of the parent plants.
Softwood cuttings are another form of wild plum propagation and should be taken in early summer when there is the most active growth. Cuttings 6- to 12-inches long with at least 2 nodes will make the best clones of the selected plant. Strip off the lower leaves and dip the cuttings in rooting hormone. Then, plant the cuttings about 1- to 2-inches deep in rooting trays of sand or rooting mix. Place the trays in a greenhouse with 60% shade. Mist the cuttings several times a day until new leaves and 1-inch roots begin to appear. Then, shift the rooted cuttings into quart or one-gallon containers of standard soil mix and reduce watering.
Root sprouts or suckers are the easiest method by which to propagate wild plums. Root sprouts about 8- to 12-inches tall can be easily dug up by cutting them from the main root and leaving 3 to 4 inches of fibrous roots attached. These young plantlets can be directly potted up into quart or 1-gallon pots of standard potting mix. Once established, they can be transplanted into a larger pot or planted in the field.
Pests, Diseases, and Other Problems
Although significantly resistant to most pest and diseases, wild plums can succumb to pests such as aphids, scale, beetle borers, American plum borers, tent caterpillars, spider mites, and plum curculios. Diseases that can attack wild plums are black knot, sooty mold, verticillium, canker, brown rot on fruit, mildew, stem decay, fire blight, and leaf spot. Wild plums can even be an over-wintering host to plum curculio and brown rot. Thus, posing a threat to local commercial peach or plum growers by possibly causing spring infestations. Birds are not usually a problem due to the large size of the fruit, but deer, foxes and coyotes love them. The profuse suckering of this tree can make it undesirable for commercial landscaping because of the excessive maintenance problem involved.
Harvest & Storage
When foraging for wild plums in the wild, keep in mind that fruit quality can vary from tree to tree. So, sample the fruit first before fully harvesting from a selected tree. Picking the fruit by hand is preferable to shaking the fruit onto a tarp because plums can be easily bruised or split. Fruit will turn from green to yellow to red with a light whitish bloom as they are ripening. When fully ripe, the plums will simply come off in your hand without pulling. The best way to store your harvest is to freeze the plums in small batches as you pick them from August through October. Once the harvest season is complete, partially thaw the plums, this will make them much less difficult to pit. Use a cherry pitter to remove the pits as they are about the same size as those of cherries. After pitting, press the plums through a food mill to remove the bitter skins. The resulting puree can be used in many cooked goods or frozen again for long term storage or dried into fruit leather.
The tart flavorsome fruit can be eaten fresh or processed into jams, jellies, wines, syrups, and sauces. If making jelly or jam, you will need to add pectin, since they don’t contain much of their own pectin. These plums can be baked in pies, tarts, breads, cakes, cobblers, crumbles, and muffins. They can also be made into vinegars or pickled. Although their flesh can be tart with a tannic after-taste, many chefs are discovering that their flavor can offer a balance to other rich foods. Wild plums can be substituted for blueberries in some recipes, but keep in mind less liquid will be needed since plums are juicier than blueberries.
An extensive array of health benefits is attributed to wild plums. Their fruit are an amazing mix of vitamins, antioxidants, minerals, and phytonutrients. They contain vitamin A, vitamin K, vitamin C, vitamin E, and the B-complex vitamins. They also have anti-oxidants like beta-carotene and flavonoids. Many minerals are also present in the fruit such as potassium, phosphorus, magnesium, iron, and copper. Whether the fruit are eaten fresh or dried (prunes), they are both high in dietary fiber.
Because of their abundant nutrients, wild plums can help strengthen the immune system, treat infections, and promote both nerve and skin health. Research has proven that regular consumption of plums is helpful in the normal formation of blood cells, blood clotting, and overall maintenance of cardiovascular health. Eating plum fruit effectively protects against cognitive impairment due to old age and assists in elevating good cholesterol (HDL) levels, as well as, decreasing bad cholesterol (LDL). But, the most well-known health benefit of dried plums and prune juice is in acting as a laxative relieving constipation.
Wild plums have been used for erosion control because they have extensive suckering root systems. Their root systems can also aid in stabilizing roadsides, banks of rivers, and drainage ditches. These small thicket-forming trees have also been used as windbreaks to shield homesteads and pastures from high winds. Because of their showy white blooms, short stature, and despite the extra maintenance needed to prune root sprouts, the wild plum has been used as an ornamental plant in residential landscapes.
Native Americans not only used wild plums as a food source, but also to make three different dyes. A green dye was made from the leaves, a dark grey dye was made from the fruit, and a red dye was obtained from the roots. Native Americans produced a decoction from the inner bark which they used to treat oral sores, skin abrasions, digestive problems, and throat infections. The blooms were used to treat sore gums, loose teeth, and mouth ulcers. Brooms for sweeping were also created by native peoples by binding wild plum twigs together.
Wild plums are an excellent habitat for wildlife. Birds such as quail and wild turkeys use them for breeding cover, roosting, nesting, and as a food source. Squirrels, foxes, coyotes, white-tailed deer, and black bears eat plums, as well as, the twigs and leaves. The wild plum is also a nectar plant. They attract moths, bees, and butterflies.
Wild plums make excellent rootstock for other hybrid plum varieties. Plum wood is prized for its heavy, strong, close-grained structure.
Recommended & Related Varieties
Over 260 varieties have been developed from the American wild plum and it has been extensively hybridized with commercial plum varieties. Many Prunus species have been crossed with the wild plum for some of its desirable characteristics and to introduce cold hardiness. For example, ‘Robusto’ plum has wild plum in its breeding for disease resistance. The three American native plums closely-related to the American Wild Plum (Prunus americana) are the Beach Plum (Prunus maritima), the Chickasaw Plum (Prunus angustifolia), and the Canada Plum (Prunus nigra). Prunus x orthosepala is a product of a natural cross between Chickasaw Plum and American Wild Plum. Some examples of commercially cultivated wild plum varieties are ‘Toka’, ‘Tecumseh’, ‘Pipestone’, ‘Fairlane ‘, ‘Underwood’, ‘Blackhawk’, ‘Desoto’, ‘Hawkeye’, ‘Klondike’, and ‘Waneta’
Hazards & Cautions
Wild plums have toxic substances in all parts of the plant except the fruit’s skin and flesh like many other Prunus species such as cherries and peaches. They contain a precursor to cyanide called hydrocyanic acid which can breakdown into cyanide once consumed.
Children are cautioned to avoid the large thorns on the terminal branches of some trees. Consuming large quantities of fresh plums can cause gastric upset and diarrhea.
In conclusion, these indigenous fruit trees with their ease of care, their many nutritional benefits, their productivity, and their attractive ornamental appearance, need to be utilized more as ornamental landscape plants, commercial orchard plants and at least be recognized as accessible foraging food sources.
- Arche Wild Native Nurseries – Quakertown, PA – archewild.com
- Flora Exotica – Montreal, Quebec – floraexotica.ca
- Native Forest Nursery – Chatsworth, GA – nativeforestnursery.com
- One Green World – Portland, OR – onegreenworld.com
References & External Links
- Boning, Charles. Florida’s Best Fruiting Plants. Sarasota: Pineapple Press, 2006.
- Brill, Steve. Identifying and Harvesting Edible and Medicinal Plants in Wild Places. New York: Harper, 1994.
- Creasy, Rosalind. Edible Landscaping. San Francisco: Sierra Club Books, 2010.
- us/docs/other/HenryKaiser2000-wildplumplantingguide.pdf. Wild Plum, December 12, 2000.
- org/user/Plant.aspex?LatinName=Prunus+Americana. Marshall. Prunus Americana, July 17, 2011.
- Reich, Lee. Uncommon Fruits for Every Garden. Hong Kong: Timber Press, 2004.
- Otto, Stella. The Backyard Orchardist. Empire, MI: Chelsea Greene Publishing, 2016.
- http:// www.wildflower.org/plants/results.php?id_plant=PRAM. Prunus americana. March 27, 2014.