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Streambank Mock Orange

Philadelphus hirsutus

Also called hairy mock orange, cliff mock orange, Cumberland mock orange.

A thin, arching southern shrub of rocky bluffs and stream banks, with white spring flowers and leaves that are white and hairy beneath.

Showy flowersDrought tolerant

Type: Shrub
Mature height: 3–10 ft
USDA zones: 4–10
Growth rate: Slow
Sun: Full, Part
Soil moisture: Dry, Average
Grows wild in: Rocky ground, stream banks and dry uplands
Native range: 9 states, north to Virginia, south to Georgia and west to Arkansas
List all 9
Alabama, Arkansas, Georgia, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee and Virginia
Also recorded in 1 other state, outside its native range. See what is native in your state

Hardiness zones Find your zone by ZIP code

Streambank mock orange is a thin, arching shrub of the hydrangea family that grows on rocky bluffs, outcrops and stream banks from Virginia and Kentucky to Georgia and Arkansas. It is the most drought-tolerant of the southeastern mock oranges and often grows on rock that is wet only part of the year. Its white spring flowers are fewer than on most mock oranges, and sources disagree on whether they are scented. North Carolina keeps it on its watch list as rare but relatively secure, and Mississippi ranks it as critically imperiled. Use it at the edge of a woodland or as a filler in a shrub border.

Size, growth and what to expect

It grows slowly, about a foot a year in our growth estimator, and reaches its full height 5 to 10 years after planting. It makes a thin, upright shrub 3 to 10 feet tall and 3 to 5 feet wide, its branches arching or sprawling. The reddish bark peels, and the new twigs are densely hairy. The leaves are 1 to 3 inches long, green above and white with hairs beneath.

White flowers about an inch across open from April into June, one to three together on short side shoots. Small, dry capsules about a quarter inch long follow and split open from June into August.

It grows wild on bluffs, rock outcrops, seepy rock and stream banks, often over limestone, mostly in and near the southern Appalachians. It is native from Virginia and Kentucky south to Georgia and west to Arkansas, and a stand in Maryland is thought to have been brought in.

How to grow Streambank Mock Orange

Streambank mock orange grows in full sun or light shade. It does best in a rich, moist soil that drains well, but it takes clay and dry spells. In the wild it often grows over limestone and other rock. Plant it 3 feet from a wall and set plants 4 feet apart. At its size it can go within 15 feet of overhead wires.

Saplings ship bare-root or potted. Plant bare-root saplings in winter, before the ground freezes, in a hole wider than the roots and no deeper, and put the native soil back in. A western mock orange sprouts better after a cold, damp spell of 20 to 75 days. Chill the tiny seed in damp sand in the refrigerator, then press it onto the surface of moist seed mix in spring, barely covered. Shade the seedlings for their first month and do not overwater them, since they are fragile.

Water weekly through the first summer if rain is short. It flowers on the previous year's wood, so prune it right after it flowers. If it grows ragged, cut its stems to the ground at that time to renew it.

Each flower carries both male and female parts, so there are no male and female plants to pair. It spreads quickly by root suckers. It has no serious pests, though leaf spot, powdery mildew, rust and aphids sometimes appear.

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

Sources (11)