Sweet William — Growing reference
| Scientific name | Dianthus barbatus |
|---|---|
| Seed germination (days) | 7–14 |
| Soil temperature for germination (°C) | 18.3–21.1 |
| First harvest or flowering (days) | 60–80 |
| Measured from | Transplant |
| Plant spacing (cm) | 22.9–30.5 |
| Mature height (cm) | 30.5–61 |
| Mature spread (cm) | 22.9–30.5 |
| USDA hardiness zones | 3–9 |
| Light | Full sun |
| Water | Moderate |
| Sowing method | indoor-start |
Growing directions
Sow seeds 1/8 in deep in well-drained germination mix; germination is fast and reliable at 65–70°F. Plant in full sun in well-drained, neutral to slightly alkaline soil; sweet William is technically a biennial that flowers in its second year, but modern annual varieties bloom the first year from an early indoor start. The domed, fragrant flower clusters in vivid shades of red, pink, white, and bicolor appear in late spring and early summer. Deadhead spent clusters promptly to extend the blooming period; plants self-sow readily to maintain a colony from year to year.
Source and local conditions
Typical planning ranges from OpenPlantDB (CC0). Cultivar, climate, season and growing method can change these values. Confirm the seed label and local guidance before planting.
Source & verification
OpenPlantDB · CC0