Syringa vulgaris 'Firmament'

RHS Plant Profile
lilac 'Firmament'

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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

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)