Sweet William
Seed # 141
Basic Information
- Seed Number
- 141
- Seed Name
- Sweet William
- Variety
- Double Flowered mixed colors
- Category
- Flower
- Plant Family
- Caryophyllaceae
- Plant Type
- Sweet William (Dianthus barbatus)
- Planting Method
- Direct Sow or Transplant
- Seed Status
- In Seed Bank
- Created
- 2026-08-14 00:50:34
- Updated
- 2026-08-19 15:35:29
Planting Information
- Start Planting Date
- Mar 10
- Last Recommended Planting Date
- Jun 15
- Plantable Months
- March, April, May, June
- Indoor Start
- Mar 10 – Mar 24
- Direct Sow
- Apr 1 – Jun 15
- Transplant
- Apr 15 – May 31
- Indoor Start Weeks Before Frost
- 8 weeks
- Transplant Weeks After Frost
- Not recorded
- Germination Days
- 7–14 days
- Harvest/Maturity
- Not recorded
- Succession Planting
- Not recorded
Growing Conditions
- Ideal Soil Temperature
- 65-72°F
- Planting Depth
- Surface sow or press lightly into growing medium
- Plant Spacing
- 6 in
- Row Spacing
- 12-18 in
- Thin-To Spacing
- 6 in
- Sun Requirements
- Full sun to partial shade
- Water Needs
- Keep evenly moist but well drained
- Soil Preference
- Rich, sandy, well-drained soil; slightly alkaline soil preferred
- Minimum Container Size
- 1 gal
- Plant Height
- 12-24 in
- Perennial/Biennial Status
- Biennial
- Container Friendly
- Yes
- Trellis/Support Needed
- No
- Frost Tolerant
- Yes
- Heat Tolerant
- No
- Drought Tolerant
- No
- Pollinator Friendly
- Yes
- Medicinal
- No
Garden Uses
Container Cut Flower Pollinator Seed SavingCompanion Planting
| Plant | Relationship | Notes |
|---|---|---|
| Zinnia | Good Companion | Not recorded |
| Zinnia | Good Companion | Not recorded |
| Zinnia | Good Companion | Not recorded |
| Zinnia | Good Companion | Not recorded |
| Zinnia | Good Companion | Not recorded |
| Zinnia | Good Companion | Not recorded |
| Zinnia | Good Companion | Not recorded |
Storage
- Seed Source/Brand
- Johnny's Selected Seeds; Ferry-Morse; Redford frost dates
- Packet Year
- Not recorded
- Quantity Notes
- Not recorded
- Purchase Date
- Not recorded
- Expiration Year
- Not recorded
- Storage Box
- Not recorded
- Container
- Not recorded
- Envelope
- Not recorded
- Row
- Not recorded
- Slot
- Not recorded
- Storage Notes
- Not recorded
Notes
Original Planting Method: Start indoors for earlier bloom, or direct sow; transplanting gives an earlier, more controlled start.
Original Start Planting Date: Mar 13 indoors; ~Apr 10 direct sow
Outdoor / Direct Sow / Transplant Window: Direct sow ~Apr 10 – May 8; transplant ~May 1 – May 20. Summer sow Jun – Jul for next-year bloom.
Days to Harvest / Bloom: Often blooms year 2; early-started plants may bloom first year (~12–16+ weeks).
Container Friendly: Yes, 12–18+ in pot with drainage
Pollinator Friendly: Yes; bees and butterflies
Medicinal / Herbal Use: Mostly ornamental/cut flower; not recommended here as a home medicinal herb.
Perennial?: Biennial / short-lived perennial
Succession / Reusable Notes: Sow some yearly or allow a few plants to self-seed for more reliable yearly flowers. Deadhead for tidiness or leave seed heads to reseed.
Zone 6B Notes: Hardy in Zone 6B. Spring sowing can begin before average last frost; summer sowing can overwinter and flower the following year.
Companion Plants: Alyssum, zinnias, pollinator herbs, cottage-garden flowers
Avoid Planting Near / Watch Outs: Avoid soggy soil and crowding; poor airflow can increase fungal problems. May self-seed.
Sources: Johnny's Selected Seeds: https://www.johnnyseeds.com/growers-library/flowers/dianthus-sweet-william/dianthus-sweet-william-key-growing-information.html | Ferry-Morse: https://ferrymorse.com/products/sweet-william-tall-double-mixed-colors | Redford frost dates: https://www.almanac.com/gardening/frostdates/MI/redford
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Zone 6B: Sweet William is hardy in Zone 6B and is naturally biennial or short-lived perennial, although it is often managed as an annual cut flower. Cool temperatures promote compact growth.
Germination: Sow 6-8 weeks before the last frost or direct sow in early spring while light frost is still possible. Germination takes 7-14 days at 65-72°F.
Harvest: For bouquets, harvest when approximately 10-20% of the flowers in each cluster are open.
Seed Saving: Allow selected flower clusters to mature until capsules dry. Mixed double-flowered plants may cross and saved seed may not reproduce the original color proportions or percentage of double blooms.
Special Care: The packet describes a mixed double-flowered population rather than a named cultivar, so exact maturity and flower color proportions are not assigned.
Research Source: Johnny's Selected Seeds — https://www.johnnyseeds.com/growers-library/flowers/dianthus-sweet-william/dianthus-sweet-william-key-growing-information.html — 7-14 day germination, 65-72°F temperature, 6-8 week indoor start, early direct sowing, 6-inch spacing, soil and harvest
Research Source: NC State Extension Plant Toolbox — https://plants.ces.ncsu.edu/plants/dianthus-barbatus/ — Dianthus barbatus identity, biennial/short-lived perennial habit, double-flowered forms, color range, sun and soil preferences
Research Source: Missouri Botanical Garden — https://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?20=&bt=8&isprofile=0&taxonid=279027 — 12-24 inch height and perennial/biennial Sweet William culture
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