Philadelphus coulteri Plant Care

Philadelphus coulteri (Philadelphus coulteri) belongs to the Hydrangeaceae family within the Philadelphus genus.

Philadelphus coulteri displays an upright, arching shrub growth habit, reaching up to 8 ft tall with a spread of approximately 6 ft. Philadelphus coulteri produces fragrant white or cream flowers in clusters.

Leaf size: approximately 4 inches.

Water a young or newly planted Philadelphus coulteri every 7–10 days, soaking the whole root zone, until it is established — usually one to two growing seasons. Established trees mainly need water during long dry spells. In a container, water whenever the top few centimetres of soil are dry.

Philadelphus coulteri thrives in full sun to partial shade.

Philadelphus coulteri tolerates temperatures of 50–80°F. Philadelphus coulteri prefers humidity levels of 40–70%.

Well-draining loamy soil with added compost for nutrients. Good drainage is essential for Philadelphus coulteri to prevent waterlogging, which leads to root rot and fungal issues.

Feed Philadelphus coulteri every 6 months during the growing season with a balanced, slow-release fertilizer at the rate on the label. Established trees in good soil often need little extra feeding, so let weak growth or pale foliage guide you.

Stop feeding by late summer so new growth can harden before winter.

The PlantoScan app can remind you when to water and when to fertilize each plant.

Choose a spot with full sun to partial shade and well-draining loamy soil with added compost for nutrients. Avoid low spots where water collects after rain.

Philadelphus coulteri is suited to USDA Zone 12a.

Plant container-grown or balled-and-burlapped trees in spring or early autumn, setting the root flare at soil level, and water well after planting.

Philadelphus coulteri can spread to about 6 ft (1.8 m) and reach about 8 ft (2 m) tall. Space plants about 6 ft (1.8 m) apart so mature crowns don't crowd each other, and plant at least half that distance from buildings, fences and paths.

Planning a row or hedge? Try the tree spacing calculator.

Prune Philadelphus coulteri while it is dormant in late winter: first remove dead, damaged and crossing branches, then thin lightly for shape.

If it flowers in spring, prune right after flowering instead so you don't remove next year's buds. Never take off more than about a quarter of the tree in one year.

Philadelphus coulteri is frost-tender (hardy to USDA zone 12). In colder areas grow it in a container and move it to a bright, frost-free place before the first frost.

Philadelphus coulteri can be propagated through softwood cuttings, hardwood cuttings. Similar propagation techniques also apply to mock orange plant care, which shares the same genus.

See all plants toxic to cats and plants toxic to dogs.

Philadelphus coulteri is susceptible to aphids, scale insects, spider mites. Inspect the foliage regularly, especially along leaf undersides and stems. Treat infestations promptly with insecticidal soap or neem oil to prevent spread.

Yellow leaves, brown tips or drooping? See common plant problems and how to fix them.

Philadelphus coulteri grows outdoors in USDA Zone 12a. It survives winters down to planting zone 12a. In cooler regions, grow Philadelphus coulteri as a houseplant or bring it indoors before the first frost.