Flower of the Week: Centaurea

June 2, 2011

This beautiful flower is something new to me this year. I bought two of them at a plant sale last spring. This looks like one big plant now, which shows you how quickly they spread. The Centaurea, also known as Cornflower or Knapweed, is just starting to come into bloom. There are a good many buds on it, and it already looks great.

From what I read in my books, they bloom in early summer, but will also have a smaller flush of blooms in autumn. We shall see if they do in my zone.

The flowers look like little thistles, but they are soft to the touch. They make excellent cutting flowers and will do well in light shade as well as full sun. Mine are getting full sun, but I will experiment with moving some into light shade.

You might be asking yourself, should you put anything in your garden that has 'weed' in it's common name? I'll let you know about this time next year!

As I've already found out, they are fast spreaders, so they probably aren't a good choice for smaller gardens. I'm the type of gardener who doesn't mind quick spreading plants, as I have lots of room to move things to, friends to give plants to, and two composters for what's left over!

And you can't have too much blue in your garden. In my garden, anyway.


  1. I have this in my garden is part shade and it still has another round of bloom in the fall, so I'd say your chances are good in your zone! They are good spreaders but not aggressive. They are one of my favorites , but then again, I have a lot of favorites!

    My lychnis is looking good so it looks like I'll be on track to have blooms every year. Yay!

  2. Hi Diane, I couldn't agree with you more, there is never too much blue in a garden :) I like the looks of this pleasantly blue plant. I'll be curious to see how much they spread. Your lovely macro pic reminds me of a 'bachelor button'.

  3. Hi Diane,
    I like growing these, too. They spread some, but not too far in my yard, anyway. If you need to pull any out, they stay pulled. I've found that I've had to replace the plants after a number of years, because they sometimes die during a winter.

    Jenni, another name for this plant is perennial bachelor button.

  4. Diane, thanks for the heads up about the comment and thanks Sue, I'm pleased to know that I wasn't crazy! lol :)

  5. So pretty, love the deep blue colour. :)

  6. Those are so compact, healthy and lush! Mine are lemons and tend to fall over!

  7. Good luck with it - it looks good now, but you can always divide and move if you need to. BTW the crotchet bag is 80-90 years old, crotched in the 1930's by my great great Aunty Jayne.

  8. I am with you 100% - you can't have too much blue in your garden! They are just lovely - I remember the "cornflower blue" crayon in the Crayola set from my childhood, but I don't think I've ever seen an ACTUAL cornflower! How great that they can also be divided. Thanks for sharing this one!

  9. You definitely can't have too much blue, I have just been spreading seeds of my Centaurea as their first flowering is now over, hope they are successful. One persons weed is anothers beautiful flower, just depends how invasive they are, enjoy yours, they are lovely.

  10. I do love those flowers, Diane, but for some reason, they've never wanted to grow in my garden. Another common name for them is bachelor buttons (which, happily, does not say "weed" at all). -Jean


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