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Eryngium 'Cobalt Star' (Sea holly 'Cobalt Star')

Beginner
skill rating
1 hour care
per year
0.7m
Max height
0.5m
Max spread
2-5 years
To maturity

Plant details

Botanical name

Eryngium 'Cobalt Star'

Other names

Sea holly 'Cobalt Star'

Genus

Eryngium Eryngium

Variety or Cultivar

'Cobalt Star' _ 'Cobalt Star' is a vigorous, clump-forming, herbaceous perennial with rounded, deeply lobed, spiny, silver-veined, dark green leaves and, in summer, dark, branching, stems bearing umbels of tiny, purple-blue, cone-like flowers with prominent, lance-shaped, spiny, purple-blue bracts.


Eryngium 'Cobalt Star' is: Deciduous

Habit

Clump-forming

Flower

Purple in Summer

Foliage

Dark-green, Veined, Silvery-grey in Spring; Veined, Silvery-grey, Dark-green in Autumn

How to care

Watch out for

Specific pests

Leaf and bud eelworms Leaf and bud eelworms

Foot and root rot , Powdery mildew Foot and root rot , Powdery mildew

General care

Pruning

Cut back flower stems after flowering, or leave attractive seedheads for winter interest.

Propagation methods

Root cuttings


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Where to grow

Eryngium 'Cobalt Star' (Sea holly 'Cobalt Star') will reach a height of 0.7m and a spread of 0.5m after 2-5 years.

Suggested uses

Beds and borders, City, Coastal, Cottage/Informal, Flower Arranging, Gravel, Rock

Cultivation

Grow in poor to moderately fertile, dry, well-drained soil in full sun. Protect from wet winter conditions.

Soil type

Chalky, Loamy, Sandy

Soil drainage

Well-drained

Soil pH

Acid, Alkaline, Neutral

Light

Full Sun

Aspect

South, East, West

Exposure

Exposed

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

Companion plants

We do not currently have companion plants added for this plant.

Botanical name

Eryngium 'Cobalt Star'

Other names

Sea holly 'Cobalt Star'

Genus

Eryngium Eryngium

Variety or Cultivar

'Cobalt Star' _ 'Cobalt Star' is a vigorous, clump-forming, herbaceous perennial with rounded, deeply lobed, spiny, silver-veined, dark green leaves and, in summer, dark, branching, stems bearing umbels of tiny, purple-blue, cone-like flowers with prominent, lance-shaped, spiny, purple-blue bracts.

Foliage

Deciduous

Habit

Clump-forming


Colour

Flower

Purple in Summer

Foliage

Dark-green, Veined, Silvery-grey in Spring; Veined, Silvery-grey, Dark-green in Autumn


How to care

Watch out for

Specific pests

Leaf and bud eelworms

Specific diseases

Foot and root rot , Powdery mildew

General care

Pruning

Cut back flower stems after flowering, or leave attractive seedheads for winter interest.

Propagation methods

Root cuttings


Monthly care advice


Where to grow

Eryngium 'Cobalt Star' (Sea holly 'Cobalt Star') will reach a height of 0.7m and a spread of 0.5m after 2-5 years.

Suggested uses

Beds and borders, City, Coastal, Cottage/Informal, Flower Arranging, Gravel, Rock

Cultivation

Grow in poor to moderately fertile, dry, well-drained soil in full sun. Protect from wet winter conditions.

Soil type

Chalky, Loamy, Sandy

Soil drainage

Well-drained

Soil pH

Acid, Alkaline, Neutral

Light

Full Sun

Aspect

South, East, West

Exposure

Exposed

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 9, Zone 8, Zone 7, Zone 6

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This plant likes... Garden match
Soil types: Chalky, Loamy, Sandy Tell us...
Soil drainage: Well-drained Tell us...
Soil pH: Acid, Alkaline, Neutral Tell us...
Light: Full Sun Tell us...
Aspect: South, East, West Tell us...
Exposure: Exposed Tell us...
Hardiness: Hardy (H4) Tell us...

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