We're offering you a up to 6 Eryngium Planum Plants for £5.99, saving you up to 40% off Thompson and Morgan's's price of £9.99 (correct as of 22.05.2025).

Steel-Blue Flowers

Eryngium planum, also known as Sea Holly, is a robust perennial prized for its striking steel-blue, thistle-like flower heads and architectural form. Belonging to the Apiaceae family, this variety creates a dramatic focal point in any sunny border or coastal garden.

• Flowering Period: Enjoy vibrant blooms from July through early autumn, offering long-lasting colour and structure.
• Wildlife Friendly: The nectar-rich flowers attract butterflies and pollinating insects, supporting local biodiversity.
• Growth Habit: Upright stems topped with spiky flower heads reach 60-90cm tall, making them ideal for mid-border planting or as statement specimens.

Growing Guide

• Sunlight: Prefers full sun and thrives in open, sunny positions.
• Soil: Grows best in well-drained, sandy or loamy soils; tolerates poor soil conditions and coastal winds.
• Watering: Drought tolerant once established; water moderately during dry spells.
• Hardiness: Fully hardy in the UK (RHS H7), suitable for most regions.

Planting & Care

• Planting Time: Plant in spring or early autumn for best results.
• Caring: Minimal pruning required—simply remove faded flower stems after blooming to encourage tidy growth.
• Fertilising: No special feeding needed; avoid rich composts which can reduce flowering.

Design Tips & Companion Plants

• Eryngium planum's spiky blue blooms pair beautifully with ornamental grasses, lavender, or echinacea for a naturalistic look.
• Adds texture and colour contrast to gravel gardens, prairie-style plantings, or contemporary borders.

FAQs

• When is the best time to plant Eryngium planum?
  The ideal planting times are spring or early autumn when the soil is workable and not waterlogged.
• How tall do these plants grow?
  Eryngium planum typically reaches 60-90cm in height when mature.
• Does it require much maintenance?
  No—these perennials are low maintenance. Just ensure good drainage and remove faded blooms as needed.