Dianthus barbatus (Sweet John, Sweet William) (2024)

FAQs

Will Sweet William come back every year? ›

No cottage garden would be without this old favorite, but it has a place in every garden. Growing up to 12-24 in. tall (30-60 cm) and 6-12 in. wide (15-30 cm), Sweet William will reseed each year in optimum growing conditions and remain in the garden.

Sweet William is best grown in deep, organically rich, well-drained soils in full sun, but generally appreciates some light afternoon shade in hot summer climates. In optimum growing conditions it will reseed each year and remain in the garden for many years as if it were a long-lived perennial.

Dianthus barbatus (Sweet William) is a biennial or short-lived perennial that is often grown as an annual. It thrives in loamy, slightly alkaline soil in sun or partial shade in hot summer climates. The flowers grow in rounded, dense clusters. Colors range from white through intense red and purple, often bicolor.

Sweet Williams are part of the dianthus family but the main difference is the type of plant they are. Dianthus plants are either annual or perennial but Sweet Williams are biennials or perennials. Wild Sweet Williams are known as phlox; they don't grow as high as Sweet Williams and are a shade loving plant.

You should ideally, plant your sweet williams in an area with full sun, though a partial or light shade can be tolerated. The soil conditions should be slightly alkaline, fairly rich, quite loose and well-draining. Make sure to mix in a general garden fertiliser before planting out, and then every 6 weeks.

Sweet William quickly produces an abundance of black seeds, which can be collected, or you can let the plants self-sow. With encouragement, sweet William will reseed for many years.

Deadheading Sweet William Flowers

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.

Dianthus need good drainage to avoid rotting and they work well in a gravel or alpine garden. They grow best in an open spot in full sun, in a neutral or alkaline soil.

Companion Planting with Dianthus

Often, other old-fashioned flowers, like roses or verbena, complement dianthus beautifully. Mild scented flowers, such as lavender or scented geraniums, work well, but be careful of strong scented plants that may detract from the aroma of dianthus.

The dianthus genus includes species that are annuals, perennials, and biennials, meaning they last for two years.

Is Sweet William invasive? ›

sweetwilliam: Dianthus barbatus (Caryophyllales: Caryophyllaceae): Invasive Plant Atlas of the United States. Dianthus barbatus L. This map identifies those states that list this species on their invasive species list or law.

If you want a wide scattering of Sweet William plants in your garden, simply let the flowers mature, die, and drop seeds on their own. Be aware that some flower varieties are hybrids of multiple plants, and may produce seeds that grow into plants with different appearance or characteristics than the parent plant.

Blue phlox, also called wild sweet William, is a perennial wildflower with lance-shaped leaves and showy, rounded clusters of (usually) lavender flowers.

SWEET WILLIAM CAN BE A GREAT BUTTERFLY AND HUMMINGBIRD PLANT | backyardwildlifeconnection.

Deadhead Sweet William when the flowers start to look tired. Don't wait too long, or the plant will begin seed production, which signals the end of the blooming cycle.

Cool-season bloomers larkspur (Consolida), sweet William (Dianthus), snapdragon (Antirrhinum majus), sweet alyssum (Lobularia maritima) and lobelia (Lobelia erinus) all are reported to be deer resistant annuals.