08/30/2026
Pretty? Pretty invasive!
This bright blue beauty might look right at home in a garden, but Mountain bluet (Centaurea montana), also known as perennial cornflower or montane knapweed, is actually an invasive garden escapee!!
Originally introduced from Europe as a popular garden perennial, Mountain bluet can easily escape into natural areas, where it can be found in meadows, pastures, roadsides, and other disturbed open areas. It spreads by both seed and roots, making established plants difficult to control.
How to identify Mountain bluet:
- 30–80 cm tall, with fine hairs covering the stem
- Large, bright blue flowers with a ray-like appearance and a black, fringed base
- Lance-shaped leaves, 10–30 cm long, with a woolly underside
- Flowers can look a lot like knapweed, so take a closer look!
Found it? Act early. Before seed production, pulling, cutting, or mowing can be effective. If flowers are present, carefully dispose of the plants in garbage bags to prevent further seed dispersal. When pulling, remove as much of the root as possible to help prevent regrowth.
A pretty plant can still be a problem when it escapes the garden. Know what you grow, and keep an eye out for Mountain bluet in your community.