Cabbage thistle

How to recognise it

Habit

Tall perennial of 50–150 cm with a straight, little-branched, grooved stem without spiny wings; few leaves higher up.

Leaf

Large, soft and pale green, undivided to deeply pinnately lobed, with a stem-clasping base with ear-like lobes and an edge with weak spines that barely prick.

Flower

Pale yellow, sometimes slightly reddish-tinged flower heads of 2.5–4 cm, clustered at the top of the stem and surrounded by large, oval, yellow-green bracts; from July to September.

Fruit/Seed

Light brown achenes with a white, feathery pappus that blow away on the wind.

Roots

A short, thick rhizome with fleshy roots; the plant forms clumps but does not spread aggressively.

Look-alikes

Marsh thistle has purple flower heads and a spiny-winged stem. Creeping thistle is lower, has small lilac heads and spreads with creeping roots. The pale yellow heads with large bracts make cabbage thistle unmistakable.

Flowering: July–September · Pruning: March and September

Why grow it?

• A top nectar plant in late summer: bumblebees, honeybees, hoverflies and butterflies visit the flower heads.
• The seeds feed goldfinches and other seed-eaters in autumn.
• Various insects, such as picture-winged flies and weevils, live in the flower heads and stems.
• A gentle thistle: its little spines are so weak that they hardly prick.
• A typical plant of flowery wet hay meadows and stream valleys; where it grows in numbers, the grassland is often valuable.
• The dry stems give insects shelter in winter.

Cabbage thistle: where does it grow best?

• In the wild in wet, nutrient-rich hay meadows, tall-herb vegetation with meadowsweet, along streams and ditches and in damp floodplain woodland.
• Sun to partial shade.
• Moist to wet, fertile soil, preferably chalky or loamy; heavy clay too.
• In the garden in a wet wildflower meadow, by a pond or ditch, or at the back of a damp border.

Goes well with

• Meadowsweet: Tall, fragrant, creamy white plumes in the same wet tall-herb vegetation.
• Purple-loosestrife: Purple spikes that flower at the same time: a lovely contrast with the pale yellow heads.
• Common valerian: Pink umbels in June–July on the same wet soil.
• Hemp-agrimony: Pink nectar-rich flowers in late summer, a magnet for butterflies.
• Yellow loosestrife: Clusters of yellow flowers at the water’s edge in July–August.

Cabbage thistle: when and how to plant it?

1. Never dig up plants in the wild: buy them from a nursery for native plants or sow your own.
2. Plant in March–April or in September–October, 40–50 cm apart, in moist soil.
3. Sow in autumn, outdoors in a tray or where it is to grow: the seed often germinates better after a cold spell.
4. Press the seed lightly onto moist soil and barely cover it.
5. Keep the soil moist in the first year; after that, water only in long dry spells in a drier spot.
6. Seedlings often only flower in their second year.

Care

Water

Not needed in a wet spot; in an ordinary border, water in dry summers.

Feeding

Not needed; the rich, wet soil it likes is enough.

Mowing

Mow a wet hay meadow with cabbage thistle once a year, in September after the seed has set, and remove the cuttings.

Leave the seed heads

Leave the spent flower heads standing: goldfinches eat the seeds.

Self-seeding

It self-seeds moderately. Pull out unwanted seedlings in spring.

Tip: Put cabbage thistle in a wet, sunny spot and leave the spent heads until winter: you will have nectar for bumblebees from July to September and then seeds for the goldfinches.

Pruning and mowing

Pruning months: March and September.

When: In the garden in March; a wet hay meadow is mown in September.

How:

• Leave the spent stems standing over winter for seed-eating birds and overwintering insects.
• In March, cut the dead stems close to the ground, before the new leaves appear.
• Mow a wet wildflower meadow in September and remove the cuttings.
• If you want fewer seedlings, cut off some of the heads after flowering.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow fresh seed outdoors in autumn, in a tray or where it is to grow; it germinates in spring. Keep the seedbed moist.

Division

In March–April, split a large clump with a sharp spade into pieces each with a few buds and replant them straight away.

Cabbage thistle: how does it get through the winter?

Hardy to −30 °C.

• The parts above ground die back in autumn; the plant overwinters as a rhizome, and in early spring a rosette of large, soft leaves appears.
• Fully hardy, to about −30 °C.
• The dry stems and fluffy heads stay standing: goldfinches eat the last seeds and insects shelter in the stems.

Diseases and pests

• Aphids: Black aphids on the stem tips in June. Ladybirds and hoverfly larvae clear them up.
• Flopping: On very rich soil and in shade the stems go limp. Plant it in sun and do not feed.
• Drying out: In a dry spot it stays small and wilts in summer. Choose a moist spot.
• Unwanted seedlings: Seedlings in a border are easy to pull up in spring.
• Fear of thistles: Neighbours sometimes think of invasive creeping thistle. Cabbage thistle does not spread aggressively and only self-seeds moderately.

Through the year

• March: Cut down dead stems. Plant or divide.
• April: Large rosettes of soft leaves appear.
• May: The stems grow.
• June: Buds appear among the yellow-green bracts. Watch out for aphids.
• July: Flowering begins: bumblebees and bees on the heads.
• August: Full flower. Butterflies on the flowers.
• September: Last flowers and fluffy seed. Mow a wet hay meadow.
• October: Sow in a tray or in place. Goldfinches on the heads.
• November: Leave the stems standing for birds and insects.

Did you know?

• Oleraceum means used as a vegetable in Latin: the young leaves and stems were once eaten cooked. The English name cabbage thistle and the Dutch name moeskruid, vegetable herb, recall the same use.
• Cabbage thistle is one of the few thistles with yellow flowers in our region.
• It sometimes hybridises with marsh thistle; the hybrids have flower heads in a colour between pale yellow and purple.