Eryngium planum Seeds - Flat Sea Holly

The Eryngium planum is a perennial blue thistle species also known as flat sea holly. In summer, it produces numerous flowers resembling small azure blue pompoms on ramified floral spikes of a steel blue hue. Its captivating colour is best appreciated in its preferred conditions: full sun, in poor, rocky, and fairly dry soil. Graphic and highly decorative, this plant is valued in slightly wild areas of the garden or in a rockery. Beautiful fresh or dried bouquets can be made with this charming plant. Sow in buckets from March to April or sow directly in place from May to July.

The Eryngium planum or Eryngium armatum, also known as flat sea holly, belongs to the Apiaceae family, just like celery and carrot. It is a perennial herbaceous plant by its root. Native to the mountains of central Europe, in the wild, it is found in dry and sunny locations, in very well-drained gravelly or sandy soil. With an upright and bushy habit, the blue thistle quickly reaches about 80 cm in height by 50 cm in spread. Its stump develops a rosette of basal leaves with petioles, ovate with a heart-shaped base, thick, dentate, dark green, shiny, evergreen in winter. Tall stems of dark blue-grey colour, branched, adorned with a few small thorned and petioleless leaves, rise from the basal rosettes. Flowering occurs in June-July at the tips of these branches. It consists of ovoid inflorescences of 2 cm in diameter, composed of numerous tiny azure blue flowers, surrounded at the base by thin dentate bracts of the same blue, with metallic reflections. This flowering attracts numerous pollinating insects. The Eryngium planum readily self-seeds in light and well-drained soils.

The Wild Blue Thistle does not live very long (especially in fertile and moist soil), but self-seeds naturally where it thrives. In a cottage garden, its colour and design are appreciated alongside tall mulleins with yellow flowers, enchanting blue annual love-in-a-mist, catmints, and shrubby salvias, but also with cosmos or roses. In a contemporary garden, it looks stunning with ornamental grasses. The cut flowers are magnificent in dried bouquets.