Silybum marianum
Blessed thistle, Our lady's milk thistle, Holy thistle, St Mary's thistle
- Height × spread
- 1.3m × 0.6m
- Position
- Full sun
- Hardiness
- Very cold to -20C (RHS H6)
- Flowers
- Summer
Availability
Please ask in store about availability
Many plants are seasonal. Call 01234 567890 to check current stock.
About this plant
This is usually an annual but can also be a biennial. It has wonderful leaves that are basically green but intensely marked with silver. The big, prickly, generally oblong leaves have waved edges and a wavy body, the overall effect being rather lavish and curious. There are purple-red, thistle-like flowers with spiny bracts.
- Flower colour
- Purple, Red
- Foliage colour
- Green, Grey
- Variegated
- Yes
- Scent
- No
- Shape
- Column
- Height
- 1.3m
- Spread
- 0.6m
- Season of interest
- Summer
- Flowers in
- Summer
- Evergreen
- Deciduous
- Garden style
- Mediterranean garden, Herb garden
- Sun or shade
- Likes full sun
- Soil type
- Chalk, Gravelly soil, Loam (normal), Poor soil, Sandy soil
- Soil pH
- Alkaline, Neutral
- Drainage
- Well drained soil
- Hardiness
- Very cold to -20C (RHS H6)
- Borders & containers
- Borders
- Hazards
- Yes, leaves are prickly
- Pet safe
- Yes – listed in our pet-safe plants
Spring
Spring - late · Outdoors
Feed with slow release fertiliser
Apply a general purpose slow release fertiliser, spreading it around the root area of the plant as it is coming into growth. (Or apply a liquid feed at regular intervals throughout the growing season.)
This is a simple way to provide a nutrient boost as a single annual procedure.
Spring-Autumn · Outdoors
Water during dry periods
For plants in the ground, when there has been little or no rain for a period of 7-10 days and the soil is dry, give it a deep watering and repeat weekly until there is a downpour of rain. Check plants in pots more frequently, especially in hot weather.
Spring-Autumn · Planting
Prune to remove flowers
Note: Foliage or flowers? Where luxurious foliage is required, or the flowers are not, to some people, especially attractive (as is often the case with hot-effect grey-foliage plants), remove developing flower stems entirely.
For plants grown for their foliage effect rather than the flowers, developing flower stems can be cut off at their base as they grow.