Floss flower

Floss flower: how do you recognise it?

Habit

Compact, rounded plant 20–25 cm tall and as wide; taller varieties reach over half a metre.

Leaves

Oval to heart-shaped, scalloped, opposite and softly hairy.

Flower

Clusters of fluffy flower heads about 1 cm across, from June to October. Each head consists only of tiny tubular florets with long, protruding styles.

Colour

Lavender to violet-blue; also pink and white.

Roots

Fine and shallow: the plant soon suffers in dry weather.

Flowering: June–October · Sowing: February–April · Plants: May–June

Why grow it?

• A rare soft blue for summer that goes beautifully with yellow, white and pink.
• Flowers non-stop from June to October.
• Stays low and compact: perfect for edging beds, in troughs and in pots.
• Attracts bees and butterflies.
• Taller varieties give pretty cut flowers for small posies.

Floss flower: where does it grow best?

• Sun or light partial shade; in full sun it stays most compact, but the soil must not dry out.
• Ordinary, humus-rich garden soil: sand, loam or clay, acid to neutral.
• Evenly moist: in dry weather the flowers soon turn brown.
• Plant 20–25 cm apart; a little closer as an edging.

Light

Sun and partial shade

Soil type

Sand, loam or clay

Acidity

Acid or neutral

Moisture

Normal

Size

0.25 m tall, 0.25 m wide

Hardiness

Frost tender: plant out after the last frost (mid-May)

Goes well with

• French marigold: Yellow and orange next to blue: a cheerful, classic contrast.
• Scarlet sage: Red spikes behind a blue edging.
• Sweet alyssum: A white, honey-scented edging next to the blue.
• Dusty miller: Silver-grey foliage that softens the blue.

Floss flower: when and how to plant it?

Plant in May–June.

1. Sow indoors in March (February–April also works) at 20–22 °C. Do not cover the fine seed: it needs light to germinate. Seedlings appear in 1–2 weeks.
2. Prick out the seedlings into small pots as soon as you can handle them and grow them on in good light, slightly cooler.
3. Harden the plants off outdoors for a week in May and plant out after mid-May, when night frosts are over.
4. Plant at the same depth as in the pot, 20–25 cm apart, and firm the soil.
5. Water in well and keep the soil moist for the first few weeks.
6. A thin layer of compost keeps the soil cool and moist.

Care

Water

Keep the soil slightly moist, especially in pots and troughs. Water at the base, not over the flowers.

Feeding

Compost at planting is enough in a border. In pots, give a liquid feed for flowering plants every two weeks.

Deadheading

The flower heads turn brown and stay on the plant. Cut off faded clusters for a tidy plant and longer flowering.

Weeding

Keep the soil around young plants weed-free until they form a closed edging.

Tip: Do not put floss flower in the driest spot in the garden: in evenly moist soil the flowers stay blue much longer.

Floss flower: when to prune it?

When: No pruning is needed. Do remove faded clusters regularly from July to October.

How:

• Cut brown, faded clusters back to just above the next leaf.
• Pinch out young plants of taller varieties once at 5–8 cm, for a fuller plant.
• Wash your hands after working with the plant: it is poisonous.

Pruning calendar and basic rules

Propagation

Seed

Indoors in February–April at 20–22 °C, seed left uncovered. Keep the compost moist under a clear lid.

Cuttings

Tip cuttings of about 5 cm root easily in summer in moist cutting compost; a good way to keep a favourite colour.

Floss flower: how does it get through the winter?

Hardy to 0 °C: protect in harsh winters.

• Not hardy: the first night frost kills the plant. It is grown as an annual.
• Clear away the dead plants in November.
• Overwintering is not worth it: sowing or buying new plants in May is easier.

Diseases and pests

• Brown flowers: In drought or heat the flower heads soon turn brown. Water evenly and cut off faded clusters.
• Powdery mildew: White powder on the leaves, especially in late summer in dry weather. Water at the base, give space and cut off affected parts.
• Whitefly: Tiny white flies under the leaves, especially in warm, sheltered corners. Spray off with water; yellow sticky traps help.
• Grey mould: Grey fluff on the flowers in wet weather. Remove faded flowers and do not water over the plant.

Through the year

• February: Early indoor sowing possible, warm and in good light.
• March: Sow indoors at 20–22 °C, seed uncovered.
• April: Prick out. Sow more for later flowers.
• May: Harden off. Plant out after mid-May.
• June: First flowers. Keep the soil moist.
• July: Remove faded clusters. Feed plants in pots.
• August: Water in dry spells. Watch for powdery mildew.
• September: In flower. Remove faded clusters.
• October: Last flowers until the first frost.
• November: Clear away dead 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.

Good for wildlife

Bees

Nectar and pollen for honeybees and wild bees.

Butterflies

Nectar for butterflies.

Did you know?

• The fluffy look does not come from petals: each head is made up of tubular florets with long, protruding styles.
• The name Ageratum comes from Greek and means ‘not ageing’: the flowers keep their colour for a long time.
• In the tropics floss flower is a persistent weed; in our climate it is killed by frost every winter.