How to grow Sweet William

Dianthus barbatus · Dianthus barbatus, bearded pink

Sweet William (Dianthus barbatus) — a biennial or short-lived perennial grown for dense, flat clusters of fringed, often fragrant flowers in white, pink, red and purple, often two-coloured. Traditionally it is sown one year to flower the next; quick-flowering varieties bloom the same summer from an early sowing.

Checked against sources: October 3, 2026

Quick facts

Type	Flower
Family	Caryophyllaceae
Light	Full sun
Soil pH	6–8
Frost	tolerates light frost
Soil for sowing	from 10 °C
Germination	10 days
Seedlings ready	40 days
Where it grows	Open ground, At home

When to plant

Sow for seedlings about 7 weeks before planting out.

It tolerates light frost: plant out in open ground about three weeks before your last spring frost.

Frost dates · When to plant

Care

Open ground

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	10…18 °C	—
Growth	every 7 days	—	—
Flowering	every 7 days	—	—

At home

Stage	Watering	Temperature	Feeding
Seedlings	every 2 days	10…18 °C	—
Growth	every 3 days	—	—
Flowering	every 3 days	—	—

Growing notes

Light

Full sun gives the most flowers; it tolerates partial shade and likes some afternoon shade where summers are hot.

Soil

Rich, well-drained loamy or sandy soil, neutral to slightly alkaline, pH 6.0–8.0. In poorly drained soil it is prone to crown rot and rust.

Care

For flowers this year, sow indoors 6–8 weeks before the last frost and press the seed lightly into the mix; it comes up in 1–2 weeks at 18–22 °C. Move seedlings into small pots about three weeks after sowing, keep them cool (10–13 °C) and plant out 6–8 weeks after sowing, 15–30 cm apart. For the traditional biennial way, sow in late spring or early summer and plant out in late summer or early autumn — it flowers the following year. Water until the plants are established, and plants in pots regularly. After flowering cut the stems to the ground — that improves the chance of flowers again next year. Watch for slugs and snails, especially in shade. Mildly toxic if eaten, including to cats, dogs and horses.

Pests and diseases of Sweet William

Rust

Sources

Figures checked against these sources.