Going to the beach to pick plums?… YES, Beach Plums!!
(Editor's Note: This article was originally published on April 23, 2008. Your comments are welcome, but please be aware that authors of previously published articles may not be able to promptly respond to new questions or comments.)
Plum is the common name for 100+ species of Prunus. Thirty of the species are native to North America, including P. domestica (greengage and prune plums), P. americana (wild red plum) and P. maritima, the beach plum (or shore plum). The beach plum is a low-growing fruiting shrub or small tree native along the sandy dunes of New York, New Jersey and Massachusetts all the way up to Newfoundland. It is most common on Cape Cod where beach plum has become a cottage commercial venture for beach plum jams and jellies.
Beach plums grow wild all over the Cape and local residents all have their own variations of sparkling clear red jams and jellies to sell in the fall at local farm stands or give as holiday gifts. Some residents even have recipes for beach plum brandy handed down from generation to generation. The prolific fruits are rather small, usually less than an inch long, and range in colors of red, pink, green, yellow, blue and purple. The fruit ripens in early September and is tart but seldom eaten fresh the way most plums are eaten. Actually, the ripe flesh is sweet and just the skin is bitter.
The photos of beach plums shown here are all from the beach (Cape Cod) where the trees seldom get more than 7 feet tall. Inland and in the right growing conditions, they can reach 18 feet tall with trunks as large as 8 inches in diameter. The best inland growing conditions are slightly acidic, somewhat dry, moderately fertile loamy soils. They dislike heavy, wet clay but will tolerate moderately drained soils. They should be mulched but not fertilized the first 2 to 3 years, and kept weeded of competing grasses. After becoming well established, beach plums are pretty carefree.
Beach Plum propagation is 4 months of cold, moist stratification of seed, or by softwood cuttings early in the season or late-summer budding. Hardiness is reported in zones 4 to 7. They can tolerate coarse, low-nutrient, low water-holding soils but neither wet sites nor shade.
There is a shrub called sand cherry that is often mistaken for beach plum. The sand cherry grows in dunes along the Great Lakes and has small, bitter black fruits.  Some similar to beach plum species are P. subcordata (Oregon and California), P. americana (central and eastern U.S.), P. augustifolia (southern U.S.) and P. nigra (northern U.S. and Canada).
The beach plum leaves have been used as a yellow or green dye, and a dark grey to green dye can be obtained from the fruit.
'Eastham' has large well-flavored fruit and is a heavy cropper.
'Squibnocket': This ornamental form has a high quality fruit and is also a good sand binder.
'Hancock': An early ripening form with golden flesh that is sweet and juicy, with little acidity. It is excellent for eating raw.
'Raribank': The purplish-red fruit is of good quality, it is freestone and ripens in late summer. It is good for jellies and for canning. A large vigorous tree, it is very resistant to brown rot and Japanese beetle
One new variety is ‘Ocean View’, developed for conservation uses in 1992 by the Cape May Plant Materials Center in Cape May Courthouse, New Jersey. It is an excellent erosion-control plant.
Most beach plums are considered self-sterile and require cross pollination for good fruit set. It is also thought that closely related bushes from within a limited area will not cross pollinate. Wild bees are the most common pollinator, followed by bumble bees and honeybees. 
Beach Plum: A New Crop for New Markets, which includes reports and a Grower's Guide (pdf format) with info on pre-plant site preparation, is available here:
Beach Plum Nurseries
Retail suppliers of Prunus maritima plants:
Other sources include the following (links will take you to their Garden Watchdog listing for contact information and customer reviews):
Lawyer Nursery, Inc.
New Hampshire State Forest Nursery
PO Box 1856
Concord, NH 03302-1856
Beach plum jam and syrup available at:
 Bailey, J.S. (1944) The Beach Plum in Massachusetts, Massachusetts Agricultural Experiment Station Bulletin Nc 442:16 pp.
Thanks to bbrookrd for use of her photos, and for the gift of the Beach Plum jelly (which is my own photo).
Beach Plum Cobbler
4 pounds beach plums, halved, pitted
1 cup sugar
2 1⁄2 tablespoons cornstarch
1 tsp. vanilla extract
2 cups all-purpose flour
5 tablespoons sugar, divided
1 tablespoon baking powder
1⁄2 tsp. ground cinnamon, divided
1⁄2 cup (1 stick) chilled unsalted butter, cut into 1⁄2 inch cubes
3⁄4 cup plus 2 tablespoons whipping cream
1 large egg
Vanilla ice cream
For filling: Preheat oven to 400F. Toss plum, sugar, cornstarch and vanilla in large bowl to coat. Transfer to a 13x9x2 inch glass baking dish. Bake until thick and bubbling at the edges, about 30 minutes.
For biscuits: Whisk flour, 3 tbsp. sugar, baking powder, salt and 1⁄4 tsp. cinnamon in large bowl to blend. Add butter in with fingertips until coarse meal forms. Whisk 3⁄4 c. whipping cream and egg in small bowl to blend. Stir cream mixture into flour mixture just until blended. Gently knead in bowl until dough comes together, about 5 minutes.
Remove beach plums from oven and stir gently. Break off golf ball size pieces of dough and arrange over hot plum mixture, spacing apart. Brush dough with remaining 2 tbsp. Cream. Mix remaining 2 tbsp sugar and 1⁄4 tsp. cinnamon in small bowl. Sprinkle over dough.
Bake cobbler until fruit is bubbling, biscuits are browned and tester inserted into center of biscuits comes out clean, about 30 minutes. Cool slightly. Serve hot or warm with vanilla ice cream.