Flowers seed -Blue alpine ,Sea Holly

Eryngium alpinum — Alpine Sea Holly — is one of the most architecturally dramatic perennials for the dry, sun-drenched garden. Upright stems rise 25–32 inches from a rosette of spiny, heart-shaped basal leaves, topped from midsummer into fall (July–October) with cone-shaped, thistle-like blue flower heads encircled by an extraordinary collar of 12–18 long, finely-divided, iridescent blue bracts. The upper stems, leaves, and flower structures all take on that distinctive steel-blue hue that makes Sea Holly so sought-after in both the garden and the vase. Native to subalpine rocky areas and moist pastures up to 6,500 ft elevation in central and southeastern Europe.

Plant Highlights

• Exceptional steel-blue flower heads with ornate, bristly bract collars
• Long bloom season: July through early October
• Excellent fresh-cut and dried flower — retains color and structure when dried
• Attracts bees and butterflies; outstanding pollinator plant
• Drought-tolerant once established (deep taproot)
• Self-sows readily but is not invasive
• Works beautifully as a single specimen or in groupings of 3–6

Growing Guide

Starting from seed: Sow indoors 4–8 weeks before last frost; allow another 4–8 weeks to reach transplant size. Seeds benefit from cold stratification — chilling at 40°F for 4–6 weeks before sowing can improve germination. Alternatively, direct sow outdoors in early spring after frost.

Important — transplant early: Eryngium develops a taproot quickly. Transplant seedlings while they are still small to avoid disturbing the taproot. Once established, plants are effectively drought-proof and should not be moved.

Site & soil: Full sun; dry to average, well-drained soil. Sea Holly thrives in lean conditions — rich or wet soil produces floppy, weak growth. Tolerates urban pollution.

Containers: Use 4½” pots (1–2 plugs) or 6” pots (2–3 plugs). Optional vernalization: 40°F (5°C) for 6–12 weeks before forcing. Forcing at 60–65°F with 16 hours of light can bring plants to flower in 14–16 weeks.

Planting Specs

• Type: Herbaceous perennial
• Height: 25–32 inches | Spread: 18 inches
• Bloom season: July–October
• Light: Full sun
• Soil: Dry to average, sharply drained; tolerates poor soils
• Drought tolerant: Yes (established plants)
• Deer resistant: Yes