Sweet William (Dianthus barbatus) is a short-lived, herbaceous perennial or biennial with a height of about 2 feet that is often planted as an annual flower. The flowering plant, with average pointed green leaves, is 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 William is mildly toxic to pets and people.
|Common Name||Sweet William, bunch pink, bearded pink, pinks|
|Botanical Name||Dianthus barbatus|
|Plant Type||Herbaceous, perennial|
|Mature Size||1-2 ft. tall, 0.5-1 ft. wide|
|Sun Exposure||Full, partial|
|Soil Type||Moist, well-drained|
|Soil pH||Acidic, neutral, alkaline|
|Bloom Time||Spring, Summer|
|Flower Color||Red, Pink, White|
|Hardiness Zones||3-9 (USDA)|
|Toxicity||Toxic to pets and people|
Sweet William Care
Easy to grow when provided with filtered sun and rich, well-drained soil, these plants self-seed each year when given optimal growing conditions, so you might have a fresh batch of beautiful flowers to admire every summer. Space sweet William plants about 8 inches apart as bedding plants to allow for the dense foliage that appears during the first year. Sweet William plants are slow spreaders so there's no need to worry about this plant overstepping its boundaries.
Unless you live in a hot Southern region, sweet William likes a full sun position over any shade. They can tolerate light shade, but too much of it results in leggy, floppy plants. In hot regions, some afternoon shade is best to help prolong the bloom time.
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 neutral to slightly alkaline one. Some growers add lime to the soil before planting.
Water sweet William regularly through the growing season, but take care not to overwater. 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° Fahrenheit can result in dormancy.
Sweet William should be fed with an all-purpose fertilizer every 6 to 8 weeks while they are growing. For the amount to use, follow product label instructions.
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 to 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 overcrowded, 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 in cell packs or containers six to eight weeks before the last spring frost. Harden them off and transplant the seedlings outside once the danger of frost has passed.
Protect your sweet William plants from the winter cold by cutting back dead foliage and blooms after flowering, but don't prune in the fall. Let the rest of the dead foliage fall to the ground to create a layer of protective mulch. Add to this a few more inches of mulch to insulate roots. If your plants are in containers outdoors, move pots away from areas that suffer from wind, snow, and ice.
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 offers a splash of color right through the summer. Under the correct conditions, sweet Williams can flower from May through to October in their flowering year. Their bright range of colors includes reds, pinks, whites, purples, and bicolors. 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.
Is Sweet William easy to care for?
You might only get one flowering season out of these plants, but they are low-maintenance. Providing they are grown under the right conditions, sweet William offers 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 or annuals. 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.
Toxic Plants (by Common Name). University of California Agriculture and Natural Resources.
Sweet William. University of California Agriculture and Natural Resources.
Dianthus barbatus. Missouri Botanical Garden.