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The Plant Guide

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Giant knapweed

Centaurea macrocephala

This clumping, robust perennial has unusual ramrod-stiff flower stems that bloom from early summer through late summer. Its fat, rusty buds open into large, deep yellow thistle flowers the size of a small fist. Easy to cut and dry for arrangements. This plant has big, coarse leaves that call for strong companions.

Noteworthy CharacteristicsA tricky plant to work into a perennial garden because it draws a lot of attention.

CareGrow in moist soil in sun or partial shade.

PropagationStart seeds in a cold frame in spring, or divide plants in spring or fall.

ProblemsWhite mold, rust, mildews, thread blight, and Southern blight.

  • Genus : Centaurea
  • Plant Width : 1 to 3 feet
  • Zones : 3, 4, 5, 6, 7, 8, 9
  • Plant Height : 3 to 6 feet
  • Light : Full Sun to Partial Shade
  • Moisture : Medium Moisture
  • Plant Type : Perennials
  • Bloom Time : Summer
  • Plant Seasonal Interest : Summer Interest
  • Flower Color : Yellow
View Comments


  1. user-6882497 07/06/2017

    I have established globe centaura macrophillia in my garden, and wish to propagate to another section of garden, Live in zone 5b Ontario Canada. Should I try to transplant one offshoot smaller plant that does not produce flowers or harvest the seed and direct sew/ If I harvest the seeds when should I sew them in --- the fall or spring ? as we have cold weather and lots of snow in winter

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