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Eryngium planum ‘Blue Cap’ (Flat Sea Holly)

Blue Eryngo 'Blue Cap', Flat Sea Holly 'Blue Cap', Eryngium 'Blue Cap', Sea Holly 'Blue Cap', False Sea Holly ' Blue Cap', Eryngium planum 'Blaukappe'

Eryngium Planum 'Blue Cap', Blue Eryngo 'Blue Cap', Flat Sea Holly 'Blue Cap', Eryngium 'Blue Cap', Sea Holly 'Blue Cap', False Sea Holly ' Blue Cap', Eryngium planum 'Blaukappe', Blue flowers, Blue perennials

Eryngium Planum ‘Blue Cap’ (Flat Sea Holly) is a clump-forming perennial with a profusion of small, steel-blue flowers, tightly packed into egg-shaped heads, that light up the garden throughout summer. Each flower is adorned with a spiky collar of narrow bracts. They are produced on silver-blue stems and stand high above the basal rosette of blue-tinged, deeply toothed, smooth textured leaves. Its beautiful texture, unique color, long-lasting flowering, easy care, and remarkable qualities as cut flowers make it a favorite of florists, gardeners, bees, and butterflies. Eryngium planum is one of the hardiest sea hollies, and it has proven to be a reliable, long-lived perennial.

  • Grows in clumps of stiffly erect, branched stems up to 2-3 ft. tall (60-90 cm) and 18-24 in. wide (45-60 cm).
  • Thrives in full sun in dry, sandy, well-drained soils. The sunnier the site, the more intense the blue! Tolerates poor soils. Avoid planting this plant in moist and fertile soils, where it will tend to sprawl and may require support.
  • Excellent choice for sun-baked, informal beds and borders or naturalistic plantings, where the steel blue flowers and foliage will superbly complement the vibrantly colored summer flowers. Ideal for small gardens. May be planted as a single specimen or in groupings. Perfect for cut or dried flower arrangements too!
  • Deadhead to preserve a neat appearance. Cut back in late summer after flowering is over.
  • Self-seeding may happen under satisfactory growing conditions but rarely becomes a nuisance.
  • Transplants poorly and is best left undisturbed once established.

Learn How To Plant, Care, and Grow Spectacular Sea Holly (Eryngium)


Attractive, Sea Holly plants (Eryngium) are striking ornamental perennials grown for their arresting, thistle-like, silvery or blue tinted flower heads adorned with a ruff of showy bracts. Blooming in summer and sometimes into fall, they are exceptionally care-free plants if they are given a well-chosen site. Here are some basic rules that need to be followed to enjoy their splendid flowers.

Requirements

Hardiness 4 - 8
Heat Zones 1 - 12
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Apiaceae
Genus Eryngium
Common names Sea Holly
Exposure Full Sun
Season of Interest Summer (Early, Mid, Late),
Height 2' - 3' (60cm - 90cm)
Spread 1' - 2' (30cm - 60cm)
Spacing 18" - 24" (50cm - 60cm)
Maintenance Low
Water Needs Low
Soil Type Chalk, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Showy
Tolerance Drought, Deer, Salt, Dry Soil
Attracts Bees, Butterflies
Garden Uses Beds And Borders
Garden Styles Prairie and Meadow, Informal and Cottage, Coastal Garden, City and Courtyard
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Alternative Plants to Consider

Eryngium leavenworthii (False Purple Thistle)
Eryngium x oliverianum (Oliver Sea Holly)
Eryngium alpinum (Alpine Sea Holly)
Eryngium alpinum ‘Blue Star’ (Alpine Sea Holly)
Eryngium x tripartitum (Tripartite Sea Holly)
Eryngium amethystinum (Amethyst Sea Holly)

Recommended Companion Plants

Lychnis coronaria (Rose Campion)
Geranium Rozanne (Cranesbill)
Stipa tenuissima (Mexican Feather Grass)
Anthemis tinctoria (Golden Marguerite)
Echinacea (Coneflower)

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Eryngium (Sea Holly)
Eryngium bourgatii (Mediterranean Sea Holly)
Eryngium planum (Flat Sea Holly)
Learn How To Plant, Care, and Grow Spectacular Sea Holly (Eryngium)
While every effort has been made to describe these plants accurately, please keep in mind that height, bloom time, and color may differ in various climates. The description of these plants has been written based on numerous outside resources.
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Requirements

Hardiness 4 - 8
Heat Zones 1 - 12
Climate Zones 2, 2A, 2B, 3, 3A, 3B, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24
Plant Type Perennials
Plant Family Apiaceae
Genus Eryngium
Common names Sea Holly
Exposure Full Sun
Season of Interest Summer (Early, Mid, Late),
Height 2' - 3' (60cm - 90cm)
Spread 1' - 2' (30cm - 60cm)
Spacing 18" - 24" (50cm - 60cm)
Maintenance Low
Water Needs Low
Soil Type Chalk, Loam, Sand
Soil pH Acid, Alkaline, Neutral
Soil Drainage Well-Drained
Characteristics Dried Arrangements, Cut Flowers, Showy
Tolerance Drought, Deer, Salt, Dry Soil
Attracts Bees, Butterflies
Garden Uses Beds And Borders
Garden Styles Prairie and Meadow, Informal and Cottage, Coastal Garden, City and Courtyard
How Many Plants
Do I Need?
Explore Great Plant Combination Ideas
Eryngium (Sea Holly)
Not sure which Eryngium (Sea Holly) to pick?
Compare Now

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