Common ragwort

How to recognise it

Habit

First a leaf rosette, the following year an upright stem of 30–100 cm, branched at the top. After flowering the plant usually dies.

Leaf

Deeply and irregularly cut, once or twice pinnately divided, with a blunt end lobe and crinkled lobes; dark green, sometimes slightly cobwebby underneath.

Flower

Yellow flower heads of 1.5–2.5 cm, with a yellow centre and usually 13 ray florets, in broad, flat clusters at the top.

Fruit/Seed

Small achenes, most with a white pappus that is carried by the wind.

Stem

Sturdy and ridged, often tinged reddish purple at the base.

Confusion with

Hoary ragwort has grey, hairy leaves with narrow lobes and grows mainly on clay and chalk. Marsh ragwort grows in wet grassland and has less deeply cut leaves. Tansy has button flowers without ray florets and fern-like, strongly scented leaves.

Flowering: June–October · Pruning: August–September

Why grow it?

• Food plant of the cinnabar moth: its black and orange striped caterpillars sometimes strip the plant bare in July.
• An important late-summer nectar source for butterflies, hoverflies, solitary bees and bumblebees.
• Dozens of insect species live on the plant, from leaf miners to beetles.
• Colours dry verges and dunes yellow into October, when few other flowers are left.
• Fits a dry, poor patch of the wildlife garden, well away from pastures with horses or livestock.

Common ragwort: where does it grow best?

• In the wild: dunes, road verges, railway embankments, dry grassland, waste ground and overgrazed pastures.
• Full sun, on dry to moist, poor sandy or loamy soil.
• It appears mainly where the soil is open and bare; in dense turf it struggles to germinate.
• In the garden: only in a dry, sunny wild patch, and not next to pastures or hay meadows for horses and livestock.

Goes well with

• Viper’s bugloss: Blue flower spikes for bees on the same dry, sandy soil.
• Bird’s-foot trefoil: Yellow pea flowers in June–August and food plant of the common blue butterfly.
• Harebell: Pale blue bells in a poor, sunny verge.
• Cat’s-ear: Yellow flowers for bees and hoverflies on dry soil.

Common ragwort: when and how to plant it?

1. You rarely need to plant it: in sandy areas it often blows in by itself. If you do want to sow it, buy seed from a native plant nursery; never dig plants up from the wild.
2. First choose a safe spot: not near pastures, hay meadows or paddocks with horses, cattle or sheep, and not where small children play.
3. Sow in September–October on bare, poor soil and press the seed in lightly; it germinates in autumn or spring.
4. Keep 30–40 cm between the rosettes you leave.
5. Water only while it germinates; after that it copes on dry soil.
6. Wear gloves when moving or pulling up rosettes.

Care

Water

Not needed, except while germinating. It grows on dry, poor soil.

Feeding

Never: poor soil keeps it sturdy and in check.

Letting it seed

Only let seed drop where it can do no harm; otherwise cut off the faded clusters before the fluff flies.

Spreading

Dense, closed turf keeps it out. Pull up unwanted rosettes with gloves, with as much root as possible.

Cinnabar moth

Leave the caterpillars alone in July: they sometimes eat the plant bare, but it usually regrows.

Tip: If you want ragwort in the garden for the cinnabar moth, keep it to one dry, clearly defined spot away from pastures and cut the stems as soon as the first fluff appears.

Pruning and mowing

Pruning months: August–September.

When: In August–September, as the flowers fade and before the fluff flies.

How:

• Let the plant flower first and wait until the cinnabar caterpillars are fully grown, late July–August.
• Cut or mow the flowering stems as soon as the first heads turn fluffy.
• Dispose of the cuttings in a sealed bag with household waste; never in hay, silage or anywhere animals can reach them.
• Be aware that cutting or mowing just before or during flowering often makes the plant live longer and flower again.

Caution: Wear gloves when cutting and pulling, and never leave cut plants where horses, cows or sheep can eat them: wilted and dried they lose their bitter taste but remain poisonous.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Seed

Sow fresh seed in September–October or March on bare, poor soil. It germinates easily; in the first year you only see a rosette.

Self-seeding

Let a few plants self-seed in a safe spot. The fluff blows far, so do not do this near pastures.

Root pieces

Broken root pieces can regrow; so pull rosettes up with as much root as possible.

Common ragwort: how does it get through the winter?

Hardy to −25 °C.

• Plants that have flowered usually die; first-year rosettes stay green all winter.
• Cinnabar moth pupae overwinter in the soil under the plants: do not dig there.
• Fully hardy.
• Remove dry stems with fluff in autumn if you do not want seedlings.

Diseases and pests

• Poisonous to livestock: Especially dangerous to horses and cattle when dried in hay. Keep it away from pastures and hay meadows and talk to neighbours who keep animals.
• Too many seedlings: On bare sandy soil it self-seeds freely. Cut the flowering stems before the fluff flies and keep the turf closed.
• Regrowth after pulling: Root pieces left behind regrow. Pull when the soil is moist, with gloves, or dig out the rosette.
• Stripped plants: Cinnabar caterpillars sometimes eat everything. No problem: that is nature at work, and the plant often regrows.

Through the year

• March: Rosettes grow. Dig out unwanted rosettes, wearing gloves.
• April: The rosettes get bigger.
• May: The flowering stems shoot up. Cinnabar moths fly and lay eggs.
• June: First flowers. Black and orange caterpillars appear.
• July: Full flower. Caterpillars sometimes strip the plant: leave them.
• August: Flowering. Cut faded stems before the fluff flies.
• September: Late flowers. Sow fresh seed in a safe spot or cut back the rest.
• October: Last flowers. New rosettes appear.
• December: Rest. Green rosettes and cinnabar moth pupae in the soil.

Did you know?

• Its Dutch and French names refer to Saint James: the plant is in full flower around 25 July, Saint James’s day.
• Cinnabar caterpillars absorb the plant’s toxins and become distasteful themselves; their bright orange and black stripes warn birds off.
• Senecio, the old genus name, comes from the Latin senex, ‘old man’, after the white seed fluff.