Purple False Thistle

As I was driving down the road I saw these beautiful purple blooms that I originally thought were Liatris but a closer inspection showed them to be False Purple Thistle (Leavenworth’s Eryngo) or Eryngium leavenworthii a native plant to Kansas. While its common name calls it a thistle this plant is actually not a true thistle but is often confused with one based on its flowers and appearance. It is actually in the Sea Holly family of striking ornamental plants grown for their flowers.

False purple thistle is an annual plant with a leafy stem that is broadly branched at the top. Almost the entire plant has some shade of purple to it with the leaves emerging as gray/green then turning purple as they mature and the royal purple thistle-like flowers that bloom from mid-summer through early fall. This plant grows from 24 to 42” tall and does best in poor soil in full sun to light shade so this plant is excellent for a shallow soil site, a rock garden or in a sunny gravel garden.

This plant is deer resistant, requires low care and tolerates heat and drought conditions. The blooms make excellent fresh cut or dried flowers in a flower arrangement just wear gloves when handling because of the prickles. I know, I’m recommending you plant a “thistle” in your flowerbeds but unlike the musk thistle I grew up with this one is a native and far better behaved than musk thistles. While it is an annual, this plant will self-sow in the flowerbed so it would not need replanting.

Have questions? Contact our office where our Horticulture Extension Agent will assist you with questions.

Phone: (316) 321-9660

Email: callae@ksu.edu