Syringa vulgaris 'Firmament'

RHS Plant Profile

lilac 'Firmament'

RHS

RHS Recommended

Trees

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A small deciduous tree with compact trusses of fragrant, pale lilac-blue flowers opening from pink buds. Heart-shaped, mid-green leaves

Position

Full sun, Partial shade

Soil Types

Chalk, Clay, Loam, Sand

Max Height

2.5-4 metres

Max Spread

2.5-4 metres

Size

Time to Maturity: 10–20 years
Max Spread: 2.5-4 metres
Max Height: 2.5-4 metres

Growing Conditions

Chalk Clay Loam Sand

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

Position

Full sun Partial shade

Aspect: South–facing or East–facing or West–facing
Exposure: 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): H6

Colour & Scent

Fragrance Flower

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Oleaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Bushy
Genus: Syringa can be deciduous shrubs or trees, with simple, entire or rarely pinnate leaves and conical panicles of small, very fragrant, 4-lobed tubular flowers in late spring or early summer
Name Status: Accepted

How to Grow

Cultivation

Tolerant of a range of conditions but grows best in moist but well-drained neutral to alkaline soil in full sun. See lilac for further advice. See lilac or large-flowered lilac for further advice

Propagation

Propagate by softwood cuttings in late spring, layering in spring, grafting in winter or chip budding in summer

Suggested planting locations and garden types

Cottage and informal garden
City and courtyard gardens
Coastal
Flower borders and beds

Pruning

pruning group 1; tolerant of hard renovation pruning

Pests

May be susceptible to lilac leaf-mining moth, willow scale and thrips

Diseases

May be susceptible to lilac blight, honey fungus, Phytophthora, Powdery mildews and bacterial canker (Pseudomonas Syringae)