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Alpine Rockery

Petrocosmea sericea

silky petrocosmea

An alpine herbaceous perennial up to 8cm high with an almost flat rosette of spoon-shaped succulent green leaves covered in silky silvery hairs and with upturned margins, and blueish-lavender flowers, about 1.5cm across; they usually have one flower per stem, the upper two petals are fused into a shorter two-lobed hood, and there is a darker purple spot at the base of the tube

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Ultimate height

Up to 10cm

Time to ultimate height

2–5 years

Ultimate spread

0.1–0.5 metres

Chalk

Loam

Sand

Moisture

Well–drained

pH

Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Partial shade

Aspect

East–facing or North–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)

Botanical details

Family: Gesneriaceae
Native to GB / Ireland: No
Foliage: Evergreen
Habit: Matforming
Genus: Petrocosmea are evergreen perennials producing low rosettes of fleshy, often felted, lance-shaped or rounded leaves. Five-lobed, tubular to bell-shaped flowers are produced in small clusters in spring
Name status: Correct
Plant range: SE Yunnan

How to grow

Cultivation

Grow in a cold greenhouse or alpine house, in indirect light, in a shallow pot of very well-drained, peat-free, loam-based compost with added grit and leafmould; water moderately while growing, and sparingly in winter, and always keep water off the leaves; in frost-free climates, grow in shade in vertical crevices in walls or rock gardens so that rain will drain away

Propagation

Propagate by seed sown as soon as it is ripe, or by leaf cuttings in summer and autumn

Suggested planting locations and garden types

Patio and container plants

Pruning

No pruning required

Pests

May be susceptible to slugs, snails, aphids, glasshouse whitefly, mealybugs, scale insects and tarsonemid mites

Diseases

May be susceptible to mildew and by crown, leaf, stem and root rots

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