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Herbaceous Perennial

Moltkia petraea

A low-growing, clump-forming hardy semi-evergreen perennial to around 25cm in height, with narrow, dark blue-green foliage with white undersides covered in fine hairs. Clusters of tubular, dark blue flowers appear on thin stems in late spring to early summer, attracting a wealth of pollinators. A great plant for an alpine garden, sandy border or crevice. Drought-tolerant once established

Synonyms

Lithospermum petraeum

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Ultimate height

0.1–0.5 metres

Time to ultimate height

2–5 years

Ultimate spread

0.1–0.5 metres

Chalk

Loam

Sand

Moisture

Well–drained

pH

Acid, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

South–facing or West–facing

Exposure

Sheltered

Drought resistance

Yes

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)

Botanical details

Family: Boraginaceae
Native to GB / Ireland: No
Foliage: Semi evergreen
Habit: Clump forming
Genus: Moltkia can be evergreen or deciduous, subshrubs or perennials, with simple, lance-shaped or linear leaves and funnel-shaped or tubular blue, purple or yellow flowers in late spring and early summer
Name status: Correct
Plant range: Balkans

How to grow

Cultivation

Grow in poor, well-drained, preferably alkaline soil in full sun. Protect from excessive winter wet and cold, drying winds

Propagation

Propagate by seed or softwood cuttings

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Gravel garden
Mediterranean climate plants
Rock garden
Flower borders and beds

Pruning

Cut back old top growth in winter

Pests

Generally pest-free

Diseases

Generally disease-free

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