Sea Holly. A prennial with spiny, mid-green leaves. Branched stems of cone-shaped, pale green at first, then steel blue flowers surrounded by spiny silvery grey bracts. Self seeds. Height 90cm. Spread 30cm. Flowers from June to August. Full sun. Well drained soil. Hardy.
Eryngium giganteum ‘Silver Ghost’ is a bold perennial valued for its spiny mid-green foliage, silvery-grey bracts, and steel-blue cone-shaped flowers. Its sculptural form adds striking structure to borders, gravel gardens, and wildlife-friendly planting schemes. This guide will help you achieve the best results for your Eryngium.
PLANTING and AFTERCARE GUIDE
Best Planting Time
Plant Eryngium giganteum ‘Silver Ghost’ in spring when the soil begins to warm, allowing the roots to establish before the flowering season. Early autumn planting is also suitable, helping the plant settle before its next active growth cycle.
Site Selection
Sunlight: Choose a location with full sun, as this encourages strong stems and vibrant flower colour. Eryngium performs best where it receives consistent daylight.
Soil: Select well-drained soil, adding grit or organic matter if necessary to improve drainage. This is essential because Eryngium giganteum ‘Silver Ghost’ dislikes overly moist conditions around the root zone.
Planting Instructions
Prepare the Hole
Dig a hole twice the width of the root ball. This allows the roots of Eryngium giganteum ‘Silver Ghost’ to spread outward easily.
Soil Preparation
Mix compost or coarse grit into the soil to enhance drainage and structure.
Planting
Place the plant so the root ball sits level with the soil surface. Backfill gently and firm the soil to remove air pockets.
Watering After Planting
Water well after planting to help the soil settle. Once established, Eryngium prefers relatively dry conditions.
Watering Requirements
Eryngium giganteum ‘Silver Ghost’ is naturally drought-tolerant once established. Water during prolonged dry spells, allowing the soil to dry between each session. During its dormant period, keep watering minimal.
Feeding
Apply a light, balanced fertiliser in early spring to support healthy new growth. A midsummer feed can help maintain strength and flowering performance throughout the season.
Pruning
Remove spent flowers to keep the plant looking tidy, or leave them in place as decorative seedheads. In late autumn, cut back stems to prepare Eryngium giganteum ‘Silver Ghost’ for its next growth cycle.
Mulching
Apply a light layer of mulch in spring to suppress weeds and help stabilise soil conditions. Avoid placing mulch directly against the crown to prevent moisture buildup.
Final Tips
Eryngium giganteum ‘Silver Ghost’ is a resilient, low-maintenance perennial that brings impressive structure, pollinator-friendly blooms, and long-lasting summer interest. Plant it in full sun with well-drained soil, and it will reward your garden with strong, architectural growth year after year.
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