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Steel-blue sea holly flower heads in a sunny borderPerennials

Eryngium planum

Sea Holly

pollinator-friendlydrought-tolerantdried flowerblueprairie plant

Sea Holly is a striking perennial with steel-blue, thistle-like flower heads on branching stems. Blooming in July and August, it adds unique texture and colour to sunny borders. Excellent as a dried flower and a magnet for pollinators.

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Before
After

Characteristics

Sun
Full sun
Water
Low
Height
50–80 cm
Spread
30–45 cm
Hardiness zone
5–9
Family
Apiaceae
Evergreen
No
Flower colors
blue
Wildlife value
bees, butterflies, hoverflies

Bloom period

Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec

Care guide

Plant in full sun in poor, well-drained soil. Sea Holly thrives in lean, dry conditions and needs no fertiliser. Too-rich soil produces floppy growth. Once established, the plant requires virtually no maintenance.

Pruning tips

Leave flower heads standing into autumn for structure and to feed birds. Cut stems back to ground level in late autumn or early spring. The flower heads also make superb dried flowers — cut them at peak bloom for drying.

Good companions

Yellow yarrow with flat flower clusters in a sunny borderPerennials

Achillea millefolium

Yarrow

Yarrow is a robust native perennial with finely divided, fern-like foliage and flat flower clusters in yellow, white, or pink. The plant blooms prolifically from June to September, attracting countless pollinators. Yarrow is remarkably drought-resistant and fits almost any garden style, from prairie borders to wildflower meadows.

Full sunLow50–80 cm
Lavender-blue flower plumes of Russian Sage in a sunny gardenPerennials

Perovskia atriplicifolia

Russian Sage

Russian Sage is a graceful sub-shrub with silvery-grey aromatic foliage and airy lavender-blue flower plumes from July to September. The plant can reach 150 cm and gives borders a hazy, ethereal quality. Russian Sage is highly drought-tolerant and thrives on poor, dry soil.

Full sunLow90–150 cm
Purple-blue flower spikes of woodland sage in a sunny borderPerennials

Salvia nemorosa

Woodland Sage

Woodland Sage is a compact perennial with striking purple-blue flower spikes blooming from June to August. It attracts plenty of bees and butterflies and works well in sunny borders. Cutting back spent flower stems often triggers a second flush of blooms.

Full sunLow30–60 cm