Common Knapweed - Centaurea nigra - Native Wildflower

Type: Perennial
Approximate height: Up to 75 cm
Flowering Time: June to September
Site and soil type: Well-drained soil in sun or partial shade
When to sow: Spring to autumn
Where to sow: Outside, direct into soil or under cover, into trays, modules or pots.
Packet contents: Approximately 150 seeds / 0.33 g

Common Knapweed, also called Black Knapweed or Hardheads, is a tall native plant with thistle-like purple flowers, found in the wild in meadows, field edges, road verges and waste ground. 

It blooms from June to September and is very popular with bees, butterflies, moths and beetles. Once it has flowered and set seed it may also attract seed-eating birds such as goldfinches.

Common Knapweed attracts / provides food for the following creatures:

  • Bees
  • Beetles
  • Butterflies including Marbled Whites πŸ¦‹ and Meadow Browns πŸ¦‹ 
  • Moths, including:   Scarce Forester moth πŸ›, Black-veined Moth πŸ›, Dusky Sallow πŸ¦‹ and Haworth's Minor πŸ¦‹
  • πŸ¦‡ 
  • πŸ¦‡ (RHS) 
  • Seed eating birds such as Goldfinches   
  • An "RHS Plants for Pollinators" plant **

Harvested from plants grown in our garden in Dumfries & Galloway, Scotland.

All our seed packets include sowing instructions.

Jemima’s Garden seeds are plastic free and reyclable. They’re contained in an inner glassine envelope, (made from pine wood cellulose), and an outer Kraft paper seed packet. Any shipping packaging is also plastic free and recyclable.

Key to symbols:

πŸ› A food plant for the caterpillar

πŸ¦‹ Provides nectar for the adult moth or butterfly

πŸ¦‡ Listed in: Bat Conservation Trust Encouraging bats, A guide for bat-friendly gardening and living

πŸ¦‡ (RHS)  Listed in the RHS Plants for Bats list

** RHS Plants for Pollinators. The RHS Plants for Pollinators mark is only given to plants that support pollinating insects. Find out more at

** The Royal Horticultural Society, and its logo, are trade marks of The Royal Horticultural Society (Registered Charity No 222879/SC038262) and used under licence.