Queen of the Centaureas

Queen of the Centaureas | A Garden for All by Kathy Diemer

Queen of the Centaureas (Photo Credit: Kathy Diemer)

When the sizzling days of summer arrive, the bold yellow thistle blooms of Centaurea macrocephala burst open to celebrate with a mini fireworks display.  This lady is the queen of sizzlers.  Each strong stem proudly holds a single golden torch like a beacon luring bees and humans alike to come in for a closer look.  The flower resembles a woven brown basket with sulfur yellow fringe hair popping out the top.  This plant is a show stopper from mid June to mid July, so be sure to plant it where you will enjoy its encore.  And don’t let the namesake of Centaurea fool you.  Unlike its delicate cornflower blue sisters ‘Montana’ and ‘Cyanus’, this bad girl will muscle in and show down the others until they pack up and relocate.  Don’t get me wrong, the other blue cornflowers or bachelor buttons (as they are commonly called) have their place as a more delicate soother in the front of the border.  But, if you’re looking for a powerhouse to “Kick it up a notch” in your summer garden, this is the plant for you.

Queen of the Centaureas | A Garden for All by Kathy Diemer

Queen of the Centaureas (Photo Credit: Kathy Diemer)

The Yellow Hardhead, Bighead Knapweed, Giant Knapweed or Lemon Fluff Knapweed (you choose the name you like) is not for the faint of heart.  It grows up to 4′ tall and 2′ wide in full sun from zones 4-8.  Even when the canary blooms aren’t on exhibition, there are plenty of other attributes to love.  The foliage growth is lush green and upright for great vertical contrast.  Before bloom, the brown artichoke/pineapple buds add architectural interest.  When the flowers have browned, I cut them back and put the seed heads right next to the original plant to ensure it will be coming back again next year.Although it is hardy to my zone 5 garden, I find it temperamental after wet winters and treat it more like a biennial than a dependable perennial.

Queen of the Centaureas | A Garden for All by Kathy Diemer

Queen of the Centaureas (Photo Credit: Kathy Diemer)

It does not require any maintenance, is trouble and pest free and very drought tolerant.  Although Centaurea macrocephala is native to the Caucasus Mountains of Turkey, it was introduced to the United States as an ornamental in the early 1800’s. You will find Centaurea macrocephala available at many garden centers or on line, however I found it listed as “prohibited noxious” in the Washington State area, so please check locally before purchasing. In any case, I adore this dazzling giant for the brazen show it puts on every summer and wouldn’t think of not inviting it back next year!


  1. I have several clumps of these in my backyard in Minnesota. They’ve survived at least 20 winters.

    • What zone is Minnesota? I’m assuming at least as cold as Connecticut (zone 5). For the last few years my centaurea has been coming back reliably, but I wasn’t sure if it was the seed heads I was leaving around? In any case, like you I’m always happy to see her cheery yellow heads! Thanks so much for writing Hans!

  2. When and how do I divide these, please?

    • Because this plant is a little temperamental for me, I haven’t divided mine. Generally, the recommendation for Centaurea is to divide every two to three years. Most perennials prefer to be divided in early spring or fall, when temperatures are more moderate. Thanks for writing, Joan~

  3. A Wiggins says:

    Very nice plant. I have not found it invasive. No bug problems. Very neat and tidy looking plant. Have had for 10 years. Transplants nicely. Highly recommended!

    • I have not found Centaurea to be troublesome in any way, she just shines year after year! I appreciate your comments, Thank you for writing!

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