Globe Centaurea, also called Great Golden Knapweed, is a robust perennial from the Caucasus, introduced to Britain by 1805. Philadelphia nurseryman Bernard McMahon sent seeds to Thomas Jefferson in 1812. The plant forms clumps 3-4' high with large, thistle-like flowers in early summer. Its chestnut-brown buds open to expose a crown of rich yellow florets. Jefferson-documented: This plant was documented by Thomas Jefferson in his Garden Book, Notes on the State of Virginia, or other writings.Start seeds indoors two to three months before last frost date, keeping soil temperatures around 70 degrees F. Transplant to 3" pots once they have several true leaves, then harden off and transplant outdoors after last frost. Approximately 40 seeds per packet. Globe Centaurea (Centaurea macrocephala) is considered an invasive plant in the following state: WA.
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