Silver ragwort

Silver ragwort: how do you recognise it?

Habit

Compact subshrub 30–50 cm tall and wide; usually grown as an annual in Belgium.

Leaves

Silvery white, felted, deeply cut and lobed, 5–10 cm long.

Flowers

Small, yellow, daisy-like flower heads in clusters, in July–August.

Hairs

The fine white hairs give the silver colour and protect the leaves from sun and evaporation.

Roots

A shallow root ball that copes poorly with wet soil.

Flowering: July–August · Sowing: February–March · Plants: April–May · Pruning: April and July

Why grow it?

• The silver-white foliage gives a calm note among colourful summer flowers and goes with blue, red and purple.
• Tolerates drought, full sun and sea wind: ideal for coastal gardens, gravel gardens and pots.
• Compact (around 40 cm) and lovely in edgings, containers and borders.
• Low maintenance: it needs hardly any water or feed.
• Stays attractive until the first frosts.

Silver ragwort: where does it grow best?

• Full sun.
• Well-drained, lean to moderately fertile soil: sand or loam, acid to chalky. Not in wet, cold clay.
• Dry to normally moist; in pots use sandy potting compost.
• Keep 25–30 cm between plants.
• The felted foliage dislikes long wet spells: choose a spot where it dries quickly.

Light

Sun

Soil type

Sand or loam

Acidity

Not fussy

Moisture

Dry or normal

Size

0.4 m tall, 0.4 m wide

Hardiness

Tolerates light frost (to -10 °C)

Goes well with

• Salvia: Blue flowers that stand out against the silver.
• Geranium (pelargonium): Red or pink flowers in the same sunny container.
• Lavender: Likes the same dry, sunny soil.
• Verbena: Purple or pink flowers against the silver foliage.

Silver ragwort: when and how to plant it?

Plant in April–May.

1. Sow in February–March indoors at 18–20 °C. The fine seed germinates in light: scatter it, press it in and barely cover it.
2. Prick out the seedlings into small pots as soon as they are big enough to handle.
3. Harden the plants off in April: outdoors by day, indoors at night.
4. Plant out in April–May, after the last night frost, 25–30 cm apart and at the same depth as in the pot.
5. Water in straight away, then sparingly.
6. A gravel or grit mulch keeps the foliage dry and suits the plant well.

Care

Water

Sparingly, at the base and not over the foliage. In pots only water when the surface is dry.

Feeding

Hardly needed. Too much feed gives floppy, green foliage that is less silver.

Removing flowers

Cut off the yellow flower stems as soon as they appear; this keeps the plant compact and silver.

Pots

Use a pot with drainage holes and sandy compost, and do not stand it in a saucer of water.

Tidying

Remove brown or rotting leaves, especially in a wet summer.

Tip: Cut the yellow flowers off as soon as they appear and the silver foliage stays compact and attractive. Put it in well-drained soil: wet feet and wet foliage are its worst enemies.

Silver ragwort: when to prune it?

Pruning months: April and July.

When: Flower stems as soon as they appear (June–August). A plant that has overwintered is cut back in April.

How:

• Cut the flower stems off at the base with scissors.
• Cut an overwintered plant back in April to about 10 cm above the ground; it shoots again.
• Remove brown, rotting or frost-damaged parts.
• Do not leave the clippings lying around: put them in the household or green waste bin.

Caution: All parts are poisonous. Wear gloves and do not leave clippings where horses, livestock or rodents can reach them.

Pruning: when and how · Pruning calendar and basic rules

Propagation

Sowing

February–March indoors at 18–20 °C (see planting). Seedlings grow slowly at first.

Cuttings

In August–September take 8–10 cm tip cuttings, set them in sandy potting compost and overwinter them frost-free and in good light; they usually root easily.

Silver ragwort: how does it get through the winter?

Hardy to −10 °C: protect in harsh winters.

• Hardy to about −10 °C on well-drained soil, but cold and wet together are fatal. In Belgium usually treated as an annual.
• Move potted plants to a frost-free, bright spot in hard frost and water hardly at all.
• Cuttings taken in August are a good insurance for next year.

Diseases and pests

• Rotting: Brown, soft foliage and a collapsing plant in wet soil and wet weather. Ensure drainage, water little and remove affected parts.
• Powdery mildew: White powder on the leaves in dry, still weather. Give plants room, water at the base and cut off affected leaves.
• Aphids: Colonies on young shoots. A jet of water is usually enough; ladybirds help.
• Slugs: May strip young plants. Collect them in the evening or spread a ring of coarse material.

Through the year

• February: Sow indoors at 18–20 °C.
• March: Prick out the seedlings.
• April: Harden off and plant out. Cut back overwintered plants.
• May: Plant, after the last night frost. Gravel mulch.
• June: Cut off the first yellow flower stems.
• July: Keep removing flowers. Water sparingly.
• August: Take cuttings.
• September: Put cuttings under frost-free cover.
• October: Bring pots in if frost threatens. Clear the plants.

Edible and useful

Not edible. These plants contain pyrrolizidine alkaloids, like the common ragwort along the roadsides: they damage the liver, even in small amounts taken in over a long time, and the damage is permanent. Horses and cattle are the most sensitive, also to dried plants in hay or silage, because they can no longer taste them: do not plant them in or beside a field, never throw mowings or trimmings near the feed, and do not cut them with grass for hay. Never make teas or herbal remedies from them, not even from hemp agrimony, which was once a medicinal herb. Keep children, dogs and cats away from the plant and wear gloves when cutting back. If any is swallowed, call a poison centre (in Belgium 070 245 245) or your doctor at once.

Did you know?

• You will also find it under the old names Senecio cineraria and Cineraria maritima.
• The felted white hairs protect the leaves from fierce sun and evaporation.
• In the wild it grows on rocks and cliffs along Mediterranean coasts; maritima means ‘of the sea’.