Sea Holly plant profile
Eryngium planum
A perennial flower for full sun.
Last updated .
When to plant
When to plant Sea Holly
Propagate sea holly most easily by separating plantlets from the base of the parent plant, or from seed (NC State). Plant in full sun in well-drained sandy or loamy soil; the more sun it receives, the more intense the blue flower color.
The calendar shows this cited seasonal window as an approximate band. It does not convert the season into frost-adjusted dates.
Open Sea Holly in my garden calendarShows the source-backed planting season, not frost-adjusted dates.
Growing conditions
- Sun
- Full sun
- Soil pH
- 6 to 8
- Lifecycle
- Perennial
- Spacing
- 12 to 36 in apart
- Hardiness
- Zones 5a to 9bFind my hardiness zone
Common problems
Watch for these
Also watch for: snails, leaf spot.
Evidence trail
Evidence behind this profile
Original extension and institutional publications behind the planting, care, and safety facts on this page.
- Eryngium planum (Sea Holly)
North Carolina Extension Gardener Plant Toolbox. Supports general reference. Checked 2026-06-18.