About
Silybum marianum, the milk thistle, is a sturdy biennial forming a handsome basal rosette of large, spiny, dark-green leaves with prominent, bright-white veins and marbling in the first year, followed in the second year by branched stems bearing large, purple, thistle-like flower heads with spiny bracts. A bold and rewarding biennial for a sunny, well-drained border or wildflower garden.
About the genus
Silybum are large, bold annuals and biennials producing basal rosettes of large, lobed, white-veined or white-marbled, spiny leaves and thistle-like, purple flower heads with spiny bracts in summer. Rewarding and architectural plants for a sunny, well-drained border.
Growing conditions
SunlightFull sun
Soil typeLoam, Sand
Soil pHAlkaline, Neutral
Soil moistureWell-drained
AspectSouth-facing, West-facing
ExposureExposed, Sheltered
UK hardinessH4
Plant details
Plant typeAnnual Biennial
HabitColumnar upright
FoliageDeciduous
Height1-1.5 metres
Spread0.5-1 metres
Time to full height1-2 years
Suggested usesCity and courtyard gardens, Mediterranean climate plants, Architectural, Cottage and informal garden
Native toMediterranean, SW Europe to Afghanistan
Care notes
CultivationGrow in poor to medium fertile, well-drained, neutral to slightly alkaline soil in full sun. Protect from excess winter wet
PruningNo regular pruning required, but flower stems may be removed to keep foliage effect
PropagationPropagate by seed sown in late spring or early summer
Pest resistanceGenerally pest-free
Disease resistanceGenerally disease-free