Centaurea
(sold as Black Gem)
Family: Compositae
Common names: HARDHEADS, KNAPWEED, STAR THISTLE
Plant
Type: annual
Forms: clumping, erect, rosette
Max height: 1.20 feet
Max width: 1.20 feet
Flower
brown/black, magenta/purple, red
Leaf
green
Horticulture
Attracts wildlife: adult butterfly, specific butterfly species
Plant features: naturalizes
Exposure: sun
Landscape uses: container, cut flower
Propagates by: seed
flowers in summer
Soil type: wide range
USDA Zones: zone 6 to -10 f, zone 7 to 0 f, zone 8 to +10 f, zone 9 to +20 f
Temp. range: -10 to +30 °F
Water: moderate
Butterflies that feed on this plant
