Cardoon

Sun

Full sun; shelter from strong winds that can tear the leaves or topple flowering stems.

Water

Water deeply during dry spells, especially when growing stalks for eating. Established ornamental plants tolerate some drought, but prolonged dryness reduces leaf quality.

Soil

Deep, fertile, well-drained soil. Avoid ground that stays wet in winter; heavy soil needs drainage improvement or a raised bed.

Height

5-8 ft (1.5-2.4 m) in flower

Spread

3-5 ft (0.9-1.5 m)

Flowers

Large violet-purple thistle heads in summer to early autumn, usually from the second year.

Foliage

Large, deeply divided, silver-grey leaves with woolly undersides; leaf edges may be spiny. Leaves die back in cold winters but can persist in mild climates.

Growth

Fast in the growing season

Care needed

Medium

• Pollinators
• Deer resistant
• Drought tolerant
• Heat tolerant
• Wildlife
• Low allergen
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Moderate

Toughness

Fairly tough

Pick your zone, country, light and whether you have pets.

1. Planting day

   1 ft (0.3 m)

2. After 1 year

   4 ft (1.1 m)

3. After 2 years

   6 ft (2 m)

   full size

About 2 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Safe

Invasive in

the US and Australia

In the garden

Spreads vigorously: plan to contain it.

Growth rate

Fast

• Allow 3-5 ft (0.9-1.5 m) between plants so the leaves can develop fully.
• Water young plants regularly, then water deeply during prolonged dry weather.
• Apply compost in spring; feed vegetable crops if growth is weak.
• Stake tall flowering stems early in exposed gardens.
• In colder gardens, mulch around the crown after the foliage dies back, keeping the crown itself free of wet, compacted material.

Pruning. Remove damaged leaves at their bases throughout the growing season. Cut spent flower stems down before seed disperses, and remove dead foliage in late autumn or early spring.

Harvest the thick leaf stalks in autumn while they are firm and tender, before hard frost. For a milder flavour, gather mature leaves loosely and wrap the stalks in opaque material for about 3-4 weeks, keeping the leafy tips exposed and checking for rot. Cut stalks near the base, remove spines and tough fibres, and cook before eating.

Early spring

Sow seeds under cover in deep pots, or divide established clumps as new growth starts.

Late spring

Harden off seedlings and plant out after hard frosts, leaving generous spacing.

Summer

Water during dry spells and stake flowering stems before they become top-heavy.

Late summer

Remove fading flower heads before seeds mature, especially where cardoon escapes cultivation.

Early autumn

Blanch mature stalks intended for eating, choosing dry weather and checking wrapped plants regularly.

Late autumn

Harvest stalks before hard frost; remove collapsed foliage and protect crowns where winters are cold.

• Use one plant as a silver-leaved focal point in a large sunny border.
• Repeat through a gravel garden with lavender and ornamental grasses for contrasting leaf shapes.
• Place at the back of a mixed border, allowing flowering stems to rise above lower perennials.
• Grow in a spacious kitchen garden as both an architectural feature and a stalk vegetable.

Garden styles it suits: Architectural minimal, Mediterranean, Dry gravel garden, Potager (kitchen garden), Edible landscape and Pollinator garden.

Plant it with: Lavender, Russian sage, Yarrow, Catmint, Purple coneflower and Feather reed grass.

Wildlife: Flowers provide nectar and pollen for bees and other insects. Seed heads attract seed-eating birds, but should not be retained where escape into surrounding land is a concern.

• Slugs and snails damage seedlings and fresh growth: inspect after dark, remove hiding places and use labelled iron-phosphate bait if needed.
• Aphids cluster on young shoots: wash them off with water and encourage ladybirds and other predators.
• Crown rot develops in wet winter soil: improve drainage and keep soggy mulch away from the crown.
• Wrapped stalks may rot during blanching: wrap only dry plants, avoid trapping water and inspect regularly.

Not known to be toxic to people, cats, dogs or horses. The leaf stalks are edible when properly prepared and cooked; spiny leaves and flower parts can cause punctures or irritation, so wear gloves.

Where it spreads. Cynara cardunculus escapes cultivation and invades grassland and pasture in California and parts of southern Australia, including Victoria, South Australia and Western Australia. Cultivated cardoon can produce spreading seedlings; check local restrictions and remove flower heads before seed develops.

• Globe artichoke (Cynara cardunculus var. scolymus)

  A closely related cultivated form selected for large, fleshy edible flower buds rather than thick leaf stalks. Foliage alone may not distinguish them reliably.

• Scotch thistle (Onopordum acanthium)

  Has conspicuously spiny wings running down its stems and generally much more heavily armed leaves; cardoon flowering stems lack these broad spiny wings.

• Milk thistle (Silybum marianum)

  Has glossy green leaves marked with bold white marbling, rather than the evenly silver-grey, deeply divided foliage of cardoon.

Cardoon comes through French from words related to the Latin carduus, meaning thistle.

Propagation. Sow seed under cover in early spring and plant out after hard frosts. Divide established clumps or detach well-rooted offsets in spring; seed-grown plants vary in spininess and stalk quality.

Accepted botanical name

Cynara cardunculus cardunculus Cynara cardunculus var. altilis is an older name for Cynara cardunculus cardunculus.

Sources: GBIF (CC BY 4.0). The care and design notes are LandscapeGPT's own.