Eryngium Planum | Blue Sea Holly
Sea Holly has been grown in American gardens since the 1800’s. Its an easy-to-grow fancy thistle with beautiful metallic, almost iridescent, bright blue, spiny flowers that sit atop 3 ft tall plants.
Sea Holly plants love sunshine and normal or sandy soil, and once established, they are extremely drought resistant and require little care. They make great specimens for low-water gardens. Seeds can be started directly outside by scattering outside in late autumn or can be started indoors, but may require vernalization/ stratification. Move seedlings to their permanent location when they are still small because Eryngium have large taproots and won’t transplant well once mature.
The species is hermaphrodite (has both male and female organs) and self fertile. Eryngium plants may or may not flower the first year from seed, but should come back with a vengeance in following years. They are valued by many for their prolonged bloom time. If you deadhead them they will keep blooming well into fall. Seeds will self-sow, but not to the point of becoming invasive.
These plants attract bees, flies, butterflies, beetles. and other pollinators like crazy! This was our garden-winner last year for ‘most visited’ by pollinators as well as having the most diverse group of pollinators too.
Almost all Eryngium make excellent, long lasting cut flowers. Harvest them when the entire flower heads and bracts turn blue so the flowers will keep their beautiful blue color after drying.
Height: 3 ft
Zones: 4- 9