How to Grow Dianthus barbatus Plants in your Garden

Gardener's HQ Guide to Growing Sweet William

Dianthus barbatus is a biennial member of the Dianthus genus and usually goes by the name of Sweet William.

Despite being a biennial or even a short-lived perennial it is usually grown as an annual in the garden. This is achieved by using cold treated plants from gardening centres and nurseries.

As the plant readily self-seeds, once it is in place more Sweet William plants will bloom each year. However these may not stay true to the original cultivar, so you may wish to remove these and grow purchased plants yearly.

The main Dianthus genus can come in many forms; annuals and perennials include the carnations, whereas the biennials include Sweet William. This page is dedicated to the biennial Dianthus barbatus, Go here for information on How to Grow Carnations and Pinks

Dianthus barbatus
Dianthus barbatus Harlequin Cultivar photograph by 阿橋 HQ; CC.

Sweet Williams and other Dianthus plants tend to have a bushy nature and grow from 30 to 75 cm in height.

Sweet William leaves


Flowers may be red, violet white or pink when one coloured; however Dianthus can often have double and triple coloured flowers, that are singular or double petalled; often with serrated edges.

Quick Growing and Care Guide

  • Scientific Name: Dianthus barbatus
  • Common Name (s): Sweet William, Bearded Pink
  • Growing Zone (USA / UK Hardiness): 3 to 9 / H7

Plant Details

  • Life Cycle / Plant Type: Biennial. Cold treated plants are grown as an annual in the garden.
  • Plant Height: One to two feet (30 to 60 cm)
  • Plant Spread: 6 to 12 inches (15 to 30 cm)
  • Blooms: Late Spring through summer.
  • Flower Details: Fragrant. Dainty. Umbel of up to 30 flowers. five petals. Serrated. Wild-type flowers are red with base of white. Cultivars include many colours such as pink, white, purples and bi-coloured. Double-flowered cultivars also available.
  • Leaf Foliages: Tapered. Lance-shaped. Blue-green. 1 1.2 to 4 inches long (4 to 10 cm).

Growing Conditions

  • Best Light Conditions: Full sunlight through to partial shade.
  • Suitable Soil Types: Well drained. Deep. Organic.
  • Suitable Soil pH: 6.0 -to 7.5
  • Soil Soil Moisture: Moist
  • Sowing, planting, and Propagation:
    Seeds do not stay true. Naturally reseeds. Sow seeds towards the end of spring and transplant to final location in autumn.
    Propagate cuttings in late spring or early summer from slips (side growth shoots). Remove leaves from the bottom inch (2.5 cm) of the slip. Dip in rooting powder. Cuttings should then be poked into seed starting potting soil in trays. Grow in the shade. Mist to keep moist. Cuttings can also be took from the root. Transplant in late spring. Cold treated plants can be planted in the autumn and will bloom the next year.
  • Care: Deadhead flowers. Water to keep soil moist. Do not get water on plant. Apply Feed to the soil surrounding the Sweet William plant (water-soluble fertilizer: once per month, or per fortnight in poorer soils).

Further Information

  • Best used for: Ornamental plant, Border, Massed planting.
  • Closely Related Species: Pinks, Carnations.
  • Miscellaneous: Deer Tolerant. Attracts wildlife such as birds and butterflies to the garden.

How to Grow Sweet William (Dianthus)

If sowing sweet William seeds outdoors then they should be sown at a depth of about 7 mm into a sunny part of the garden (from mid spring to July).

They should be grown with a spacing of 20 to 25 cm apart in a deep and rich slightly acidic to neutral soil (pH 6 to 7).

Sweet William is a biennial so will flower in the second year. If you prefer to start seedlings of Sweet Williams off indoors, then they should be started about eight weeks before they are transplanted into the garden in autumn (or late spring).

Germination at a temperature of about 20 degrees Centigrade takes from one to two weeks.

Caring for Dianthus

If you require more Dianthus plants then cuttings can be took from the root.

Common Questions

What genus and family does Sweet William belong to?

Sweet William belongs to the genus Dianthus, and the family Caryophyllaceae.

Does Sweet William make a good garden or landscaping plant?

Yes, Sweet William is a popular choice for gardens and landscaping. It adds beauty with its showy, fragrant flowers and comes in a variety of colors.

Are Sweet William plants fragrant?

Yes, these plants are known for their delightful fragrance, which adds to their overall appeal in gardens and flower beds.

What is the perfect location to grow Sweet William?

Sweet William thrives in a location with well-drained soil and full sun to partial shade. It is versatile and can be grown in borders, rock gardens, or cottage-style landscapes.

Is Sweet William invasive in the USA, if so in which states?

No, it is not considered invasive in the USA. It is a cultivated plant that is commonly grown in gardens, and does not pose a threat to natural ecosystems.

How do I remove Sweet William plants from my garden?

To remove Sweet William plants from your garden, simply uproot them carefully, making sure to remove the entire plant, including the roots. Dispose of the plant material properly to prevent any reseeding.


Sweet William, scientifically known as Dianthus barbatus, is a biennial or short-lived perennial flowering plant. It belongs to the family Caryophyllaceae and the genus Dianthus. Sweet William is native to Europe, and is highly valued for its showy and fragrant flowers. These come in a variety of colors.

To grow Sweet William, choose a location with well-drained soil and provide it with full sun to partial shade. Sow the seeds in spring or early summer, or plant nursery-grown plants. It is important to keep the soil moist during the germination and establishment period. Once established, Sweet William requires moderate watering and occasional fertilization. Deadheading spent flowers promotes continuous blooming. This versatile plant can be used in borders, rock gardens, or cottage-style landscapes, adding both beauty and fragrance to the garden.

I hope that you enjoyed this guide on how to grow Dianthus Sweet William plants. You may also enjoy the following Gardener's HQ Caryophyllaceae growing guides: How to grow Irish moss and Gypsophilia plants.