Northwest Blooms · Perennials
Eryngium planum
Flat Sea Holly
- Family
- Apiaceae
- Height
- 30 to 40 inches
- Width
- 12 to 18 inches
- Flower color
- Bluish to purplish, forming globular heads
- Foliage color
- Gray-green with spiny margins
- Bloom time
- June to September
- Light
- Full sun
- Water
- Low to moderate
- Maintenance
- Low; minimal care required
- Growing zone
- USDA zones 3 to 9
- Wildlife
- Attracts bees and butterflies
About this plant
Eryngium planum, commonly known as flat sea holly, is a perennial native to regions including the Alps, Jura, and the Balkan mountains. In summer, it produces steel-blue, thistle-like flower heads atop branched stems, rising from a rosette of dark green, deeply toothed basal leaves.
This plant thrives in full sun and is drought-tolerant once established, making it suitable for dry, sandy, well-drained soils. Its unique texture and color provide lasting interest in the landscape, and it serves as a valuable addition to gardens, attracting bees and butterflies.
Works well in
Borders · Sun Gardens · Pollinator Gardens · Waterwise Gardens · Cut Flower Gardens
Companion plants
Ornamental grasses · Garden phlox · Black-eyed Susans · Daylilies · Lavender · Coreopsis
Design tip
Foliage and form do most of the work here, so lean on texture and repetition rather than one flowering moment. In full sun it holds its shape best, and grouping several together keeps the color strong enough to be seen from across the garden.
