Eryngium (Sea Holly) in Zone 7a & 7b
Eryngium planum
When to plant eryngium (sea holly) in zone 7b
Zones 7a and 7b share the same average frost dates in our data, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. Eryngium (Sea Holly) needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Jan 9–Jan 16 |
|---|---|
| Direct sow / transplant outside | Apr 17–Apr 24 |
| Estimated bloom | Apr 16 '28–Apr 23 '28 (~365 days after transplanting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Eryngium, commonly called sea holly, looks like a thistle crossed with a metal ornament, its spiny bracts taking on a blue or silvery sheen that holds up well both fresh and dried.
How eryngium (sea holly) fits zone 7's season
Zone 7b's frost-free window runs about 198 days, from April 10 to October 25. Eryngium (Sea Holly) needs about 365 days from transplant to first harvest.
Good companions
No standout companions recorded yet for Eryngium (Sea Holly).
Where to buy eryngium seeds
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing eryngium (sea holly)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 7b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →
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Growing Eryngium (Sea Holly) in USDA zone 7b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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