Highlights

Captivating Steel-Blue Blooms – Distinctive thistle-like flowers from July to early autumn.
Pollinator Friendly – Attracts butterflies and beneficial insects to your garden.
Drought Tolerant & Hardy – Thrives in well-drained soil and full sun, ideal for UK gardens.
Perfect for Sunny Borders – Flourishes in coastal locations and open beds.
Low Maintenance – Requires minimal care once established, perfect for busy gardeners.
Mature Height – Reaches approximately 60-90cm, adding height and texture.

We're offering you a up to 6 Eryngium Planum Plants for £4.99, saving you up to 50% 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.