Sweet William Growing Guide

Dianthus barbatus

Sweet William

Crop Rotation Group



Well-drained soil enriched with plenty of compost, with a neutral to slightly alkaline pH.


Full sun to part shade, which can prolong bloom time in hot summer areas.

Frost tolerant

Yes. Sweet William easily survives winter temperatures to 0°F (-18°C), and grows as a short-lived perennial in mild winter climates. Where winters are very cold it can be grown as a cool-season annual.


Drench with a liquid organic fertilizer when plants show vigorous new growth in spring.


Single Plants: 7" (20cm) each way (minimum)
Rows: 7" (20cm) with 7" (20cm) row gap (minimum)

Sow and Plant

Start seeds indoors in late winter and expect seeds to germinate after 7 to 10 days. Set plants out while the weather is still cool, under the protection of row cover (garden fleece). Exposing the seedlings to cool spring weather encourages first-year flowering. You also can start seeds in midsummer, sowing the seeds where you want the plants to grow. Sweet William that becomes established in late summer blooms very heavily the following spring.
Our Garden Planner can produce a personalized calendar of when to sow, plant and harvest for your area.


Varieties vary in color, size, fragrance and growth habit. Tall, long-stemmed varieties for cutting work well when grown with foxgloves or bellflowers.


Sweet William quickly produces an abundance of black seeds, which can be collected, or you can let the plants self-sow. With encouragement, sweet William will reseed for many years.


Slugs and snails can be aggravating in spring.

Planting and Harvesting Calendar

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Pests which Affect Sweet William