Milk Thistle in a pot | Medicinal plant

Latin name

Silybum marianum

Common name

Milk thistle

Type

Annual or biennial medicinal plant

Family

Asteraceae

Milk thistle is a very distinctive medicinal annual or biennial plant, recognized for its white-marbled green foliage and large, wild-looking purple flowers. Its robust and architectural habit brings height, texture, and a lot of character to medicinal plant gardens, naturalized flowerbeds, specialized vegetable gardens, and country-style landscapes. Very decorative, it easily stands out with its contrasting spiny leaves and its original, eye-catching bloom.

Easy to cultivate, milk thistle prefers a sunny location in well-drained, light to moderately fertile soil. It tolerates dry conditions quite well once established and is suitable for gardens requiring resistant, structured, and low-maintenance plants. As its foliage is spiny, it is best to reserve a spot for it where it can develop without hindering passage, at the back of a flowerbed, in a medicinal garden, or in a naturalized area.

Traditionally recognized as a medicinal plant, milk thistle is also appreciated for its ornamental interest and its ecological value in the garden. Its flowers attract pollinators, while its seeds can attract certain birds at the end of the season. It is an ideal plant to add a strong, botanical, and textured presence to a useful plant garden, a wild border, or a sunny landscape with a natural style.

Care guide

Care level

Easy

Choosing this plant

Main benefit

Very decorative marbled foliage and traditional medicinal plant

Medicinal garden, naturalistic border, pollinator garden, architectural plant

Container growing

Possible to grow in a large, deep, well-drained container

Seasonal care

Harvest seeds when ripe; wear gloves to handle the spiny foliage; deadhead flowers to limit self-seeding

Growing conditions

Light, soil, water and hardiness

Hardiness zone

Not hardy

Exposure

Full sun

Watering

Moderate; allow the soil surface to dry slightly between waterings

Humidity

Low to average humidity; tolerates drought once established

Fertilization

Light compost for seedlings; avoid excessive fertilizer

Soil type

Light to medium, dry to cool, well-drained soil

Soil pH

Neutral to slightly alkaline

Minimum temperature

32 °F

Propagation method

Direct seeding

Blooming period

Summer

Flower color

Purplish pink to purple

Fruiting

Medicinal seeds at the end of the season

Foliage color

Green mottled with white

Foliage type

Obsolete

Shape

Large spiny rosette then erect flower stalks

Height

90 to 150 cm (36 to 60 inches)

Width

60 to 90 cm (24 to 36 inches)

Growth rate

Rapid growth

Vegetable garden and yield

Companion planting, spacing and harvest

Companion plants

Calendula, yarrow, sage, lavender

Plants to avoid

Avoid with small, fragile plants (risk of shade or competition)

Spacing

45 to 60 cm (18 to 24 inches)

Harvest period

August to October

Pets

Butterflies

Deer

The availability of our plants varies depending on arrivals, seasons, nursery production and supplier availability. Some varieties may be offered for a limited time only, depending on their natural cycle or current stock. These plant profiles are designed to guide and inspire you when choosing plants for the garden, landscaping projects, containers or long-lasting outdoor arrangements.