How to grow Sweet William in the UK
Dianthus barbatus
Sweet William (Dianthus barbatus) is a flower that grows well in UK gardens. Treat as biennial — sow this year, flowers next year. Brilliant for cutting; lasts a week in vase. This guide covers when and how to sow Sweet William, the soil and position it likes, watering and feeding, companion planting, and when to harvest.
When to sow & grow Sweet William
Sowing and harvest window through the year (UK):
Jan | Feb | Mar | Apr | May | Jun Sow | Jul | Aug | Sep Plant | Oct | Nov | Dec |
Soil, position & care
- Soil
- Fertile, moisture-retentive but free-draining soil
- Soil pH
- 6.0–7.5
- Position
- Sun or part shade depending on species
- Sowing depth
- Plant at the same depth as the pot
- Spacing
- 30–60 cm apart
- Sowing
- Plant container-grown stock spring or autumn; divide established clumps in spring
- Growing
- Water well the first season until established; mulch in spring
- Harvest & upkeep
- Cut back faded foliage in late autumn or early spring; divide every 3–4 years
- Watch for
- Slugs and snails on new shoots; otherwise robust
Companion planting for Sweet William
No specific companion notes for this plant.
Add Sweet William to your free 12-month plan and get watering & sowing reminders — no sign-up needed.
Sweet William FAQs
When should I sow Sweet William in the UK?
In the UK, sow Sweet William in June. Sowing across these months gives the plant the right soil temperature and day length to establish well.
How much sun does Sweet William need?
Sweet William prefers full sun (6+ hrs direct).
Is Sweet William easy to grow?
Easy — good for beginners. Treat as biennial — sow this year, flowers next year. Brilliant for cutting; lasts a week in vase.