Culture
Easily grown in average, medium moisture, well-drained soils in full sun to light shade. Prefers moist, organically rich soils. Tolerates a wide range of soils except poorly-drained ones. Flowers appear on the prior year’s growth, so prune as needed immediately after flowering.
Noteworthy Characteristics
Philadelphus schrenkii, commonly called mock orange, is a dense, upright, multi-stemmed, deciduous shrub that typically grows to 4-6' (infrequently to 12') tall and as wide. It is native to mixed forests in eastern Siberia, northeastern China and Korea. It is grown in landscapes primarily for its very fragrant, 4-petaled, creamy white flowers (each to 1 1/2" across) which cover the shrub with an abundant bloom in spring (May - June in St. Louis). Flowers appear in small 5-7 flowered clusters (racemes). Each flower purportedly resembles the shape of an orange blossom, hence the common name of mock orange. This shrub is also sometimes commonly called syringa which is somewhat difficult to comprehend because Syringa is the genus name of lilacs. Flowers give way to seed capsules. Ovate to oblong-lanceolate leaves (3-5" long) with acuminate tips and lightly serrate margins have pubescence on the veins below. Gray bark exfoliates with age.
Genus name comes from the Greek word philadelphus meaning loving one’s brother or sister. A Grecian and Roman family name. New York Botanical Garden suggests that the genus name instead comes from Ptolemy Philadelphus, a king of the third century B.C.
Problems
No serious insect or disease problems. Some susceptibility to leaf spot, canker, powdery mildew and rust. Aphids, nematodes, scale and leaf miners are occasional visitors.
Uses
Foundation plantings, shrub borders, open woodland gardens, low screens or hedges. This shrub has minimal ornamental interest when not in flower.