Philadelphus coulteri

RHS Plant Profile

Coulter's mock orange

Other common names

rose syringa

Shrubs

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One of the most attractive Mexican species, forming an upright, arching shrub to about 2m tall with dark green foliage that has a whitish-grey, hairy underside. Clusters of large, flat, scented white flowers appear in summer and make this a highly desirable garden plant

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

1.5-2.5 metres

Max Spread

1.5-2.5 metres

Size

Time to Maturity: 5–10 years
Max Spread: 1.5-2.5 metres
Max Height: 1.5-2.5 metres

Growing Conditions

Chalk Clay Loam Sand

Moisture: Moist but well–drained or Well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun Partial shade

Aspect: East–facing or North–facing or South–facing or West–facing
Exposure: Exposed or Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H5

Colour & Scent

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Hydrangeaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Philadelphus are deciduous shrubs with simple, opposite leaves and bowl-shaped, usually fragrant flowers which may be solitary or in small panicles or racemes in summer
Name Status: Correct
Plant Range: Mexico

How to Grow

Cultivation

Grow in moist, well drained soil in sun to partial shade. Plant bare root plants in winter when the ground is not frozen or waterlogged. Incorporate lots of well-rotted manure or garden compost to improve the soil and water in well. Mulch in spring

Propagation

Propagate by softwood or hardwood cuttings

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Low Maintenance
Flower borders and beds

Pruning

Pruning group 2

Pests

May be susceptible to aphids

Diseases

May be susceptible to honey fungus (rarely) and powdery mildews