Sometimes known as mock orange, this is a deciduous shrub for mid- to late-spring blooms which does well in the Sydney climate as well as in cooler climates. There are around 80 species that can be found growing on mountain slopes from western China to Mexico, North and South America, Italy and Austria. All Philadelphus are strongly fragrant, with exquisite large white single, semi-double or double cup-shaped blooms with prominent central stamens.
Many of the best cultivars were raised by the French nursery Lemoine in the early 20th century. A well-known cultivar is Philadelphus 'Virginal' with double white perfumed flowers on an arching shrub to 2.5-3 m tall. 'Natchez' has single blooms and grows 2.4-3 m tall. Smaller versions include 'Belle Etoile' (ht 1.2-1.8 m) with a purplish stain in the base of its large single white flowers; and for very compact spaces there is 'Manteau d'Hermine' (ht 75 cm) with double white, highly perfumed blooms. Philadelphus coronarius is 2-3 m tall and has single flowers. Its cultivar 'Aureus' (ht 2.5 m) has delightful yellow leaves in spring, which change to lime in summer. It needs a more protected position than other Philadelphus, to avoid sunburn on the leaves. P. mexicanus (ht 5-6 m) is an evergreen climbing form.
The shrubs should be pruned straight after flowering by removing one-third of old stems at ground level and giving the remaining stems a light clipping, cutting back to just above new growth. Very overgrown old specimens can be rejuvenated by removing half the oldest, largest branches at ground level one year (after flowering) and removing the rest of the old growth the following year. Each year after pruning, apply some general-purpose fertiliser and a mulch of compost or well-rotted manure. Philadelphus like a position in at least half sun, and reasonable moisture in their early years. Once established, they tolerate considerable dryness. They can be propagated from softwood cuttings in summer or hardwood cuttings in autumn or winter.
Flowers in October, November.