Philadelphus delavayi

Philadelphus delavayi, or Delavay’s mock orange, is a deciduous shrub in the Hydrangeaceae family. Its native range covers parts of China and reaches Myanmar. Sources include Sichuan, Yunnan and southeastern Tibet within that range. It grows in a temperate climate. Wild plants occur in scrub, mixed woods and thickets. They also grow on mountain slopes and beside streams.

This shrub has an upright, bushy form. Garden plants reach about 8–13 feet [2.5–4 metres] tall and wide. The RHS describes a height of 10–13 feet [3–4 metres]. Plants take about five to ten years to reach full size. The leaves are slender and dark green, with toothed edges. They fall before winter, leaving the shrub bare until new growth returns. White flowers open in summer and have a strong scent. Purple calyxes contrast with the white blooms.

Grow it in sun or partial shade. It needs soil that drains well but stays moist. The RHS lists clay, chalk, loam and sand as suitable soils. It also accepts acid, neutral and alkaline conditions. Both open and sheltered sites suit it. The RHS rates its hardiness as H6. Plants For A Future lists USDA zones 5–9. Plant bare-root stock in winter, avoiding frozen or waterlogged ground. Add well-rotted manure or compost when planting, then water well. Apply mulch in spring. Softwood and hardwood cuttings offer ways to raise new plants.

Its size suits a mixed border or a woodland edge. It also fits cottage gardens, courtyards and less formal planting schemes. Plants can form a loose hedge or screen. The scented summer flowers add interest during the growing season. The RHS includes it among choices for gardens needing little upkeep. Aphids may attack the plant. Powdery mildew can also affect it. Honey fungus is another possible problem, though the RHS calls it rare.

Plants For A Future lists no known food or medicinal uses. It also reports no known hazards. That does not establish that the plant is safe to eat. Its leaves contain saponins, which make lather when crushed with water. The source describes this lather as a mild cleaner. It can clean skin or clothes but works poorly on oil. Plants For A Future does not flag the shrub as weedy.