Eryngium Big Blue

Eryngium ‘Big Blue’ (Sea Holly) is a real statement perennial, loved for its architectural shape and bold colour. It produces striking, spiky flower heads in steel-blue tones, surrounded by jagged, thistle-like bracts that look incredible in sunny borders. Tough, drought-tolerant and brilliantly low maintenance once established, it’s perfect for gravel gardens, coastal planting, prairie-style borders and anywhere you want strong structure with very little fuss.

It’s also a superstar for cutting—fresh stems add texture to bouquets, and it dries beautifully too, holding its colour and shape for long-lasting arrangements.

Planting Instructions

When to Plant:

Plant bare root Eryngium in spring or autumn, while the soil is moist and workable. Avoid planting when the ground is frozen or waterlogged.

Where to Plant:
Choose a sunny position with well-drained soil. Eryngium thrives in poor, gritty or sandy soils and dislikes heavy, wet ground. Ideal for gravel gardens, coastal gardens, prairie-style planting and wildlife-friendly borders. The more sun and drainage it gets, the better the colour.

How to Plant:

• Before planting: Soak the bare roots in water for 30–60 minutes to rehydrate.
• Depth: Plant so the crown sits level with the soil surface.
• Spacing: Space plants 30–45 cm (12–18 inches) apart.
• Soil Prep: Avoid rich compost. Instead, improve drainage with grit on heavier soils and keep the planting area relatively lean.

Watering:
Water well after planting. Keep watered during the first growing season while roots establish. Once established, Eryngium is drought tolerant and only needs watering during prolonged dry spells.

Aftercare Tips:

• Leave flower heads for winter interest and wildlife, then cut back in late winter or early spring.
• Avoid heavy feeding—too much fertility can reduce colour and cause softer growth.
• Eryngium dislikes being moved once established, so choose its spot carefully.

Top Tip:
For a designer-style border, pair Eryngium ‘Big Blue’ with ornamental grasses, Achillea and lavender—the steel-blue flowers add amazing contrast and structure.

Plant Details

Flowering Period:

July - September

Height:
24–36" (60–90cm) approx.

Position:
Full sun

Hardy Perennial