Silver Sea Holly Seeds produce a hardy perennial plant known for its spiky, metallic silver-blue flowers and silvery, thistle-like foliage. This clump-forming plant thrives in full sun with well-drained soil and is suitable for garden borders, rock gardens, and naturalized landscapes. Once established, Silver Sea Holly is drought-tolerant and provides long-lasting color, texture, and seasonal interest while attracting pollinators such as bees and butterflies.
Features
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Clump-forming perennial growth habit
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Produces spiky, silver-blue flowers with thistle-like foliage
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Suitable for garden borders, rock gardens, and naturalized landscapes
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Thrives in full sun with well-drained soil
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Drought-tolerant once established
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Attracts pollinators and adds texture to gardens
Specifications
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Scientific name: Eryngium giganteum
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Common name (US): Sea Holly
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Seed type / variety: Perennial flowering variety
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Growth habit: Clump-forming perennial
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USDA zones: 4 to 9
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Planting season: Spring
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Growing season: Late spring through summer
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Sowing Season: Spring
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Sowing season months: March to May
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Germination time and conditions: 14 to 28 days; cold stratification improves germination
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Sunlight requirements: Full sun
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Soil requirements: Well-drained, sandy or loamy soil
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Watering needs: Low; drought-tolerant once established
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Mature plant size: 2 to 3 feet tall; 1 to 2 feet spread
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Plant spacing: 12 to 18 inches apart