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 coronarius, commonly called mockorange or sweet mockorange, is a dense, rounded, multi-stemmed, suckering, deciduous shrub with stiff, straight, ascending but arching branches. It typically matures to 10-12’ tall and as wide. It is native to southeastern Europe and Asia Minor. It is grown in landscapes primarily for its 4-petaled, very fragrant, white flowers (each to 1 1/2” across) which bloom abundantly in May to early June in small clusters (5 to 7- flowered racemes). Each flower purportedly resembles the shape of an orange blossom, hence the common name of mockorange. Flowers give way to seed capsules. Dark brown 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.
Specific epithet from Latin means used for or relating to garlands in reference to the flowers.
‘Romanizam’ is a patented cultivar sold in commerce under the trade name of ROMANTIC KNIGHT. It was discovered growing in a seed bed as a naturally occurring whole plant mutation by the inventor, James W. Zampini, in 1997. The plant parents are unknown. Attributes of this cultivar are (1) large, semi-double, fragrant, white flowers (2” diameter) in racemes (each having up to 14 flowers), (2) mounded, spreading plant habit with arching branches, and (3) fruits (4-valved capsules). Flowers are nearly double the size of the flowers found on most cultivars of this species. U.S. Plant Patent PP25,303 was issued on February 24, 2015.
Problems
Some susceptibility to leaf spot, canker, powdery mildew and rust. Aphids, nematodes, scale and leaf miners are occasional visitors. Deer tend to avoid this plant.
Uses
Foundation plantings, hedges, cottage gardens, shrub borders or low screens. This shrub has minimal ornamental interest when not in flower.