Plant Passport Registration Number: GB147173
Please read our notes before placing the order:
1. The pictures in this listing are examples of the available plant at maturity and do not indicate anything in regard to size of plant at the point of sale.  You will receive an organically produced young plant grown in a 9cm pot for planting immediately or to grow on (pot removed, when possible, to reduce plastic waste)
2. Seasonal difference in plants: Please be aware if you are new to gardening, that the plants we supply are mostly herbaceous perennials and many go dormant in winter. You may receive what looks like an empty pot or piece of root. This will produce new growth in spring.
3. The date the Royal mail label is bought (tracking number added as sent against your orders) is the date your order is lined up for picking.  It is likely to be put into the post a couple of days later. 
Thank you.
Centaurea nigra - Common Knapweed is an upright, branching perennial to 75cm, with simple or pinnately lobed leaves and thistle-like purple flowerheads to 4cm across, with conspicuous blackish involucres. Prefers a well-drained fertile soil in a sunny position. Tolerant of dry, alkaline soils and established plants are tolerant of considerable neglect. Self-seeds readily and can become invasive.
Height: 50-75cm in 2-5 years
Spread: 20-30cm