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Eryngium planum 'Tetra Petra' (Sea holly 'Tetra Petra')

Beginner
skill rating
1 hour care
per year
0.9m
Max height
0.5m
Max spread
2-5 years
To maturity

Plant details

Botanical name

Eryngium planum 'Tetra Petra'

Other names

Sea holly 'Tetra Petra'

Genus

Eryngium Eryngium

Variety or Cultivar

'Tetra Petra' _ 'Tetra Petra' forms clumps of branched stems, and cone-like, large, dark blue flowerheads with spiny bracts in late summer.


Eryngium planum 'Tetra Petra' is: Deciduous

Habit

Clump-forming

Flower

Dark-blue in Summer; Dark-blue in Autumn

Foliage

Dark-green in Summer

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 them as the seedheads are a very attractive feature through winter.

Propagation methods

Seed


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Where to grow

Eryngium planum 'Tetra Petra' (Sea holly 'Tetra Petra') will reach a height of 0.9m and a spread of 0.5m after 2-5 years.

Suggested uses

Coastal, Cottage/Informal, Flower Arranging, Beds and borders, Gravel, Wildlife

Cultivation

Plant in dry, well-drained soil that is poor or moderately fertile. Full sun is essential. Protection from any winter wet.

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 planum 'Tetra Petra'

Other names

Sea holly 'Tetra Petra'

Genus

Eryngium Eryngium

Variety or Cultivar

'Tetra Petra' _ 'Tetra Petra' forms clumps of branched stems, and cone-like, large, dark blue flowerheads with spiny bracts in late summer.

Foliage

Deciduous

Habit

Clump-forming


Colour

Flower

Dark-blue in Summer; Dark-blue in Autumn

Foliage

Dark-green in Summer


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 them as the seedheads are a very attractive feature through winter.

Propagation methods

Seed


Monthly care advice


Where to grow

Eryngium planum 'Tetra Petra' (Sea holly 'Tetra Petra') will reach a height of 0.9m and a spread of 0.5m after 2-5 years.

Suggested uses

Coastal, Cottage/Informal, Flower Arranging, Beds and borders, Gravel, Wildlife

Cultivation

Plant in dry, well-drained soil that is poor or moderately fertile. Full sun is essential. Protection from any winter wet.

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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