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Alpine RockeryHerbaceous Perennial

Onosma alborosea
  • RHS AGM

An evergreen, clump-forming perennial up to 25cm in height with oblong or lance-shaped white bristled grey-green, leaves. In summer, bears bunches of tubular white flowers, turning to pink and purple as they mature, atop short stems

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Size
Ultimate height
0.1–0.5 metres
Time to ultimate height
2–5 years
Ultimate spread
0.1–0.5 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Well–drained
pH
Alkaline, Neutral, Acid
Colour & scent
StemFlowerFoliageFruit
Spring White Grey Silver Green
Summer White Pink Purple White Grey Silver Green
Autumn White Grey Silver Green
Winter White Grey Silver Green
Position
  • Full sun
Aspect

South–facing or West–facing

Exposure
Exposed or Sheltered
Drought resistance
Yes
Hardiness
H5
Botanical details
Family
Boraginaceae
Native to the UK
No
Foliage
Evergreen
Habit
Clump forming
Name status

Unresolved

How to grow

Cultivation

Plant sideways in a wall, or in a scree bed, well-drained trough or rock crevice. Avoid winter wet. Alternatively, grow in an unheated greenhouse in a gritty compost mix of loam, leaf mould and grit. Avoid watering the foliage

Propagation

Propagate by seed in autumn, in a cold frame or sheltered position outside

Suggested planting locations and garden types
  • City and courtyard gardens
  • Cottage and informal garden
  • Rock garden
  • Gravel garden
Pruning

No pruning required

Pests

May be susceptible to aphids or glasshouse whitefly under glass

Diseases

Generally disease-free

Get involved

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