Sea Holly – Eryngium planum Share this:Click to share on Pinterest (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on Twitter (Opens in new window) Designed with love! Our Grower's Choice Subscription freshly picked and delivered to your door every month. Shop Now Common Name: Blue Thistle, Sea Holly Botanical Name: Eryngium planum, e-RIN-jee-um PLAY-num Decorative Life: Flowers 10-12 days, foliage 5-8 days. Flower Color: Blue Availability: Year Round Harvest Instructions: Harvest when flowers are fully open. Plants should be grown in full sunlight for maximum quality. Storage Specifics: Cold storage intensifies flower color. 34-38 degrees F. Tidbits: E. amethystinum is also used for cut flowers. Eryngium is a Greek name for some sort of thistle. The specific epithet name “planum” means flat. Plants of this family often exhibit strong or pungent odors, many are grown for food, flavoring and medicinal reasons while some are also grown for ornamental purposes. Can be used fresh or dried. Harvest when flowers are fully open.