Laserpitium siler

RHS Plant Profile

laserwort

Synonyms

Laserpitium siler

Herbaceous Perennial

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A hardy, clump-forming, architectural deciduous perennial with deeply divided blue-green foliage and large umbels of pink to white flowers which appear in early summer. Good for pollinating insects. Seed heads can be left over winter

Position

Full sun

Soil Types

Chalk, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 1–2 years
Max Spread: 0.1-0.5 metres
Max Height: 0.5-1 metres

Growing Conditions

Chalk Loam Sand

Moisture: Well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun

Aspect: 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): H7

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Apiaceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Clump forming, Columnar upright
Genus
Name Status: Synonym
Plant Range: S & SC Europe

How to Grow

Cultivation

Grow in well-drained soil, gravel or rock gardens in full sun in a dry location

Propagation

Propagate by fresh seed in autumn, or in a damp vermiculite mixture under glass with bottom heat for 3 weeks, then in cooler conditions for around 8 weeks prior to sowing

Suggested planting locations and garden types

Architectural
Cottage and informal garden
Gravel garden

Pruning

No pruning required. deadhead regularly and cut back in autumn

Pests

Generally pest-free

Diseases

Generally disease-free