Facebook LinkedIn Email Pinterest Twitter Instagram YouTube Icon Navigation Search Icon Main Search Icon Video Play Icon Audio Play Icon Headphones Icon Plus Icon Minus Icon Check Icon Print Icon Note Icon Heart Icon Filled Heart Icon Single Arrow Icon Double Arrow Icon Hamburger Icon TV Icon Close Icon Sorted Hamburger/Search Icon

The Plant Guide

Browse the Full Plant Guide

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

Plant Characteristics are only available to Fine Gardening members

Sign up for a free trial and get instant access to our complete plant guide as well as our entire collection of articles and videos.

Start Free Trial

Related Plants

Related Articles

More From the Plant Guide

Winter Interest

Partial Shade

Browse the Full Plant Guide