Silver Ghost Sea Holly ,Flower Seeds - Perennial

Eryngium giganteum — Silver Ghost Sea Holly, ‘Miss Willmott’s Ghost’ — is one of the most hauntingly beautiful plants in the ornamental garden. At dusk, the silvery-white flower heads covering most of the plant glow with an ethereal luminosity. Very large spiny flower heads in an unusual silvery-grey with a greenish cone at the center are surrounded by dramatic filigreed bracts. Tends to act as a self-seeding biennial that returns for several years without becoming a nuisance weed. Superb for cutting, fresh or dried. Drought tolerant once established. RHS Award of Garden Merit recipient. Zones 4–9.

Garden legend holds that English plantswoman Ellen Willmott used to secretly scatter seeds of this plant in other people’s gardens — hence the name.

Plant Highlights

• Silvery-white glowing flower heads with filigreed bracts and a greenish central cone — ethereal beauty at dusk
• Self-seeding biennial returning for several years — not invasive
• Outstanding cut and dried flower — harvest before fully open for best dried results
• Drought tolerant once established
• RHS Award of Garden Merit (AGM) recipient
• Attracts pollinators; beloved by flower arrangers
• Height: 60 cm (approximately 24 inches) | Bloom: July–September | Zones 4–9

Sowing Guide

Germination requires a two-stage temperature stratification process — follow carefully for best results:

1. Surface sow indoors (February–July). Sow on moist, well-drained seed compost; cover lightly with vermiculite. Do not bury.
2. Warm phase: Maintain at 18–22°C for 2–4 weeks. Place container in a polythene bag.
3. Cold stratification: Move to refrigerator at ~4°C for 3–6 weeks.
4. Return to warmth: No warmer than 18°C. If germination does not occur within 6–10 weeks, return to refrigerator for a further 3–6 weeks.
5. Important: Check seeds regularly while in the refrigerator — remove any that show signs of germination immediately and move to warmth.
6. Prick out into 8 cm pots, acclimatize, and plant out after all danger of frost has passed.

Care Guide

Light: Full sun; tolerates very light shade.

Soil: Light, well-drained soil preferred. Plant into its final position while young — roots are often several feet long and deeply resent disturbance.

After flowering: Cut flower stems back after blooming, or leave the attractive seedheads for winter interest and natural self-seeding. Cut flowers before fully open if drying. Divide carefully in early spring or autumn — be gentle due to the deep root system.

Winter: Protect from excessive winter wetness. Will self-seed reliably.

Planting Specs

• Common name: Silver Ghost Sea Holly, Miss Willmott’s Ghost, Giant Sea Holly
• Botanical name: Eryngium giganteum
• Family: Apiaceae
• Type: Self-seeding biennial / perennial
• Bloom: Silvery-grey spiny heads with filigreed bracts; ivory white
• Bloom time: July–September
• Height: 60 cm (~24 inches)
• Zones: 4–9
• Light: Full sun (tolerates very light shade)
• Soil: Light, well-drained
• Sowing: Surface sow Feb–July; two-stage stratification required
• Awards: RHS Award of Garden Merit (AGM)
• Use: Cut flower, dried flower, borders, cottage gardens