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Centaurea nigra (Common knapweed)

Beginner
skill rating
1 hour care
per year
0.6m
Max height
0.5m
Max spread
2-5 years
To maturity

Plant details

Botanical name

Centaurea nigra

Other names

Common knapweed, Lesser knapweed, Hardheads

Genus

Centaurea Centaurea

Species

C. nigra - C. nigra is an upright perennial with grey-green, hairy, lance shaped leaves. In summer it has spiky, dark purple-pink flowerheads on branched stems.


Centaurea nigra is: Deciduous

Habit

Upright

Flower

Purple-pink, Dark-purple in Summer

Foliage

Grey-green in Summer; Grey-green in Autumn

How to care

Watch out for

Pests

Generally pest free

Powdery mildew Powdery mildew

General care

Pruning

Deadheading helps to prolong the flowering season.

Propagation methods

Division


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Where to grow

Centaurea nigra (Common knapweed) will reach a height of 0.6m and a spread of 0.5m after 2-5 years.

Suggested uses

Coastal, Flower Arranging, Beds and borders, Containers, Wildflower, Wildlife

Cultivation

Grow in well-drained soil in full sun.

Soil type

Loamy, Sandy

Soil drainage

Well-drained

Soil pH

Acid, Alkaline, Neutral

Light

Full Sun

Aspect

South, West

Exposure

Exposed, Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

Companion plants

We do not currently have companion plants added for this plant.

Botanical name

Centaurea nigra

Other names

Common knapweed, Lesser knapweed, Hardheads

Genus

Centaurea Centaurea

Species

C. nigra - C. nigra is an upright perennial with grey-green, hairy, lance shaped leaves. In summer it has spiky, dark purple-pink flowerheads on branched stems.

Foliage

Deciduous

Habit

Upright


Colour

Flower

Purple-pink, Dark-purple in Summer

Foliage

Grey-green in Summer; Grey-green in Autumn


How to care

Watch out for

Pests

Generally pest free

Specific diseases

Powdery mildew

General care

Pruning

Deadheading helps to prolong the flowering season.

Propagation methods

Division


Monthly care advice


Where to grow

Centaurea nigra (Common knapweed) will reach a height of 0.6m and a spread of 0.5m after 2-5 years.

Suggested uses

Coastal, Flower Arranging, Beds and borders, Containers, Wildflower, Wildlife

Cultivation

Grow in well-drained soil in full sun.

Soil type

Loamy, Sandy

Soil drainage

Well-drained

Soil pH

Acid, Alkaline, Neutral

Light

Full Sun

Aspect

South, West

Exposure

Exposed, Sheltered

UK hardiness Note: We are working to update our ratings. Thanks for your patience.

Hardy (H4)

USDA zones

Zone 10, Zone 9, Zone 8, Zone 7, Zone 6, Zone 5

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This plant likes... Garden match
Soil types: Loamy, Sandy Tell us...
Soil drainage: Well-drained Tell us...
Soil pH: Acid, Alkaline, Neutral Tell us...
Light: Full Sun Tell us...
Aspect: South, West Tell us...
Exposure: Exposed, Sheltered Tell us...
Hardiness: Hardy (H4) Tell us...

DISCUSS THIS PLANT

Centaurea nigra

Common knapweed is thistle-like in appearance but without spines. Its dark flowerheads with pink-purple flowers are very attractive to insects including hoverflies, bumble bees and a range of… read more

There is 1 active discussion about Centaurea nigra (Common knapweed)

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