How to Grow and Care for Sweet William

Sweet Williams plant with bright and light pink frilly flowers

The Spruce / Gyscha Rendy

Sweet William (Dianthus barbatus) is a short-lived, herbaceous perennial or biennial flowering plant ideal for use in cottage gardens, perennial beds, or containers. The flowers come in many vibrant shades and are attractive to pollinators like butterflies, bees, and hummingbirds.

Planting Sweet William in late spring will usually produce flowers the following year, although some new cultivars bloom in the first year if you start the seeds early enough. Research suggests that sweet Williams are mildly toxic to pets and people.

 Botanical Name Dianthus barbatus
Common Name Sweet William, bearded pink, pinks
 Family Caryophyllaceae
 Plant Type Herbaceous, Perennial
 Mature Size 1-2 ft. tall, 0.5-1 ft. wide
 Sun Exposure Full sun, part shade
 Soil Type Moist, Well-drained
 Soil pH Acidic, Neutral, Alkaline
 Bloom Time Late Spring, Summer
 Flower Color Red, Pink, White, and Bicolor
Hardiness Zones 4a-9b, USDA
 Native Area Europe
 Toxicity Toxic to pets and people

Sweet William Care

Easy to grow when provided with filtered sun and rich, well-drained soil. The plants readily self-seed each year under optimal growing conditions, so you will likely have a fresh batch of beautiful flowers to admire every summer. Space Sweet Williams about eight inches apart as bedding plants to allow for the dense foliage that appears during the first year.

Sweet Williams plant with circular and frilly pink and white flowers in sunlight

The Spruce / Gyscha Rendy

Sweet Williams plants with pink, white and red circular flowers in sun lit garden

The Spruce / Gyscha Rendy

Sweet Williams plant with circular pink and light pink flowers clustered together

The Spruce / Gyscha Rendy

Light

Unless you live in a hot Southern region, Sweet William appreciates a full sun position. They can tolerate light shade, but too much shade results in leggy, floppy plants. In hot regions, some afternoon shade is a good to help prolong the bloom time.

Soil

Sweet William can tolerate many soil types, except wet, heavy conditions. A well-drained, fertile, loamy site is ideal. The plants can survive in soils with various pH levels too but often do best in a slightly alkaline one. Some growers add lime to the soil before planting.

Water

Water Sweet William regularly through the growing season, but take care not to over-water. Waterlogged conditions promote fungal diseases in this species. A moist but not saturated substrate is best.

Temperature and Humidity

For a flowering plant, Sweet William is relatively cold-hardy. It can survive light frosts, but deep freezes will result in the plant dying down. This species doesn't do well with high humidity, and temperatures above 85° Farhenheit can result in dormancy.

Fertilizer

Sweet William should be fed with an all-purpose fertilizer every couple of months while they are growing.

Propagating Sweet William

Propagating Sweet William from cuttings is possible. However, because these plants are short-lived, many people simply purchase cold-treated plants during the spring to grow them as annuals.

How to Grow Sweet William From Seed

Sweet William is easy to grow from seed, but they don't typically bloom the first year. The seed can be sown into the ground in the late spring or early summer when there is no danger of frost. They prefer cool temperatures of around 50-55 degrees Fahrenheit and consistently moist soil for germination. Temperatures above 65 degrees Fahrenheit can result in weak, leggy growth.

These plants don't like to be over-crowded, so, as the seeds germinate, thin them out so there is adequate air circulation.

If you want to see blooms in the first year of planting, you could try sowing the seeds indoors six to eight weeks before the last spring frost. Harden them off and transplant the seedlings outside in cell packs or containers once the danger of frost has passed.

Common Pests & Plant Diseases

Fungal diseases like rust and crown rot can be a problem for Sweet William if it is planted in poorly drained soil or overwatered. It is also attractive to slugs and snails.

How to Get Sweet Williams to Bloom

With their small clusters of flowers, Sweet Williams offer a splash of color right through the summer. Under the correct conditions, these biennials can bloom from May through to October in their flowering year. Their bright range of colors includes reds, pinks, whites, purples, and variegates. Some flowers are fragrant, but many cultivars are scentless. Their fringed and bearded petals are what give them their alternative "bearded pink" name.

Ensuring Sweet William has moist but well-drained soil is crucial for healthy and abundant bloom production. Overly hot temperatures also impact flowering capabilities. Deadheading spent flowers will also encourage more blooms. However, stop deadheading in the late summer to encourage self-seeding for new plants the following year.

FAQ
  • Is Sweet William easy to care for?

    You might only get one flowering season out of these plants, but they are low-maintenance and easy care Providing they are grown under the right conditions, Sweet William provide a proliferation of blooms for minimal effort.

  • How long does Sweet William live?

    Although technically a short-lived perennial, these plants are usually grown as biennials. Generally, they will only produce foliage during their first year of growth and then an abundance of blooms in their second year before dying at the end of the bloom season. Occasionally, they will bloom again for the third season.

  • Does Sweet William make a good cut flower?

    This species is a popular cut flower because it is long-lasting, has a strong stem, and large, attractive flower heads. Healthy cut flowers can last several weeks.

Article Sources
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  1. University of California Agriculture, and Natural Resources. “Toxic Plants (by Common Name).” Ucanr.edu. N.p., n.d. Web.

  2. Dianthus barbatus. Missouri Botanical Garden