Sweet William
Dianthus barbatus
An ornamental plant, sown May to July.
In September: nothing to do. It can be planted out now. Wear gloves: it can cause a skin allergy.
Your first month is free. No card. Then £4.99 a month or £39.99 a year. You sign in with a link we email you, with no password.
Sweet William, month by month
Bar: the usual months. Sprout: this month.
| Sowing, planting or job | Sep | Oct | Nov | Dec | 2027Jan | Feb | Mar | Apr | May | Jun | Jul | Aug |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Sow under cover. | none | none | none | none | none | none | none | none | usual | usual | usual | none |
| Sow outdoors. | none | none | none | none | none | none | none | none | usual | none | usual | none |
| Plant out. | usual | usual | usual | none | none | none | none | none | none | none | none | none |
| Clear away the dead sweet William stems and leaves. | none | none | none | none | none | none | none | none | none | usual | none | none |
| Deadhead the sweet William. | none | none | none | none | none | none | none | none | none | usual | usual | usual |
What to do, and when
The usual months for a UK garden. Your own plan gives the week.
Handle it with care
Wear gloves: it can cause a skin allergy.
Strong source: RHS.
Sowing and planting
Sow under cover May to July, on the surface. Moderate source: Sarah Raven.
Sow outdoors May, and July, 0.5cm deep, 15cm apart, rows 30cm apart. Strong source: RHS.
Plant out September to November, 30cm apart. Strong source: RHS.
Clear away the dead sweet William stems and leaves
Clear the whole plant once its seed pods start to brown, and plant half-hardy annuals in its place.
Usually June. Moderate source: Sarah Raven.
Deadhead the sweet William
Usually June to August. Moderate source: Sarah Raven.
What the source words mean
Strong: the RHS page for this plant is among them.Moderate: another trusted UK source, or the RHS on its group.
Every line above names the page it comes from. Where we found no good source for a job, we left it out. Where the name “Sweet William” comes from.