Photo: Charles Edward Faxon, Public domain · Wikimedia Commons

Allegheny Plum

Prunus alleghaniensis

Also called Allegheny sloe, Porter plum.

A rare thicket plum of the Appalachians, with white flowers that fade to pink and small dark purple plums under a blue bloom.

RareEdibleWildlife valueBears young

Type: Shrub
Mature height: 3–20 ft
USDA zones: 4–8
Growth rate: Medium
Sun: Full, Part
Soil moisture: Dry, Average
Grows wild in: The Appalachians, rocky ground, old fields and edges
Native range: 12 states, north to Michigan, south to North Carolina and west to Tennessee
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Connecticut, Kentucky, Maryland, Massachusetts, Michigan, New Jersey, New York, North Carolina, Pennsylvania, Tennessee, Virginia and West Virginia
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Allegheny plum is a small, sometimes thorny wild plum of the Appalachians. It grows from Connecticut and New York south in the mountains to Tennessee and North Carolina, with an outlying population in Michigan. It was named as a species only in 1877, and botanists still disagree about it. Some botanists now fold it into the hog plum of the Southeast, while others keep it apart. It is scarce across its range. Maryland lists it as threatened, Connecticut counts it as extirpated, and Virginia keeps it on its watch list. In the mountains of Pennsylvania and West Virginia its fruit was known as sloe and used for preserves. Grow it as a small fruiting thicket at a sunny woodland edge, where it can sucker freely.

Size, growth and what to expect

Allegheny plum grows as a multi-stemmed shrub or a very small tree up to about 20 feet, spreading as wide by root suckers. Often it stays a shrub a few feet high. No source rates its speed, so our growth estimator treats it as a medium grower, a foot and a half a year. It is difficult to grow from seed or from cuttings.

White flowers half an inch across open in April and May in small clusters, and they fade to pink as they age. The plums are round, about half an inch across and dark reddish purple under a blue bloom, and they ripen in August and September. That blue-bloomed fruit sets it apart from American plum. Beach plum, a look-alike, has hairy flower stalks and larger fruit.

In New England it grows on river banks, sandy river bottoms, fields and roadsides. Elsewhere it grows in rocky upland woods, on shale ridges and on limestone bluffs.

How to grow Allegheny Plum

Allegheny plum wants full sun or light shade and a well-drained soil, average to dry, like the rocky slopes and old fields where it grows wild. Pull stray root suckers, or let it build a thicket. Set plants 10 feet apart, and keep them 10 feet from a wall. It is small enough to stand within 15 feet of overhead wires.

Saplings ship bare-root or potted. Plant them dormant, from leaf fall until bud swell, in a hole wider than the roots and no deeper. Set the crown at the soil line, put the native soil back in, and keep the mulch clear of the stems. Sow the pits in fall an inch deep under hardware cloth. For spring, hold them damp in the refrigerator for about five months first. Only about a quarter of the seed comes up in tests, so sow plenty.

Water weekly through the first summer, then only in a long drought. Rabbits and voles gnaw the thin stems and deer browse the shoots, so guard young plants with wire for the first two or three years. Prune only to take out dead stems, and cut back suckers that stray past the bed.

Plums need pollen from a second plum to set fruit, and a thicket from one root counts as one plant, so plant two or more from different seed. Seedlings can bear from about their fourth year, and a large crop can come every year. Birds and mammals take the fruit as it ripens.

Heights and zones are typical ranges for the species in cultivation; local conditions and seed source shift them.

Sources (9)