Sweet William is an herbaceous biennial or a short-lived perennial in the same family as Carnations and Pinks. Dianthus Barbatus grows wild in the mountains of southern Europe. It was only in the 1600s that it started being cultivated for its ornamental qualities in northern Europe.

The plants grow 6 to 18 inches tall and bear dense clusters of flowers at the top of their stems. Sweet William bloom in colours of pink, red and white, and each flower is 2-3 cm in diameter with five petals and serrated edges. The lush green foliage holds its space well even after flowering. Sweet William is an easy-to-care for plant that is suitable for beds, borders, containers, cut flowers and potpourris. A favourite with butterflies and bees.

GROWING INSTRUCTIONS

The short-lived perennial is often grown in cottage gardens, perennial beds and containers. Dianthus showcases bushy foliage and brightly coloured flowers of many shades. 

Seeds can easily be started indoors or outdoors. Sow directly outside in late spring or early summer after the danger of frost has passed. The first year of outdoor growth doesn’t typically produce flowers. However, seeds started indoors may flower in their first growing season. 

Six to eight weeks before the last frost, seeds can be started in flats or separate containers. Sow seeds on the surface of moist soil and mist well. Put them in a bright location, under lights or by a sunny window, and keep them moist. Dianthus prefers cooler weather when germinating. Maintain an ambient temperature of 10-13 degrees. When they start to sprout, thin them out to provide space and good air flow. Seedlings can then be hardened off and transplanted outdoors after the danger of frost has passed. 

Dianthus will do best in full sun, although in hot regions, afternoon shade will help extend the blooming window. Plant Dianthus in rich, well-drained, loamy soil. Keep the soil moist with regular watering, but don’t allow it to become waterlogged. Dianthus is tolerant to many climates, except extreme heat. It will withstand light frosts, but will be killed by hard freezes. To promote blooming and vigorous growth, fertilize Dianthus once every couple of months. 

Space Dianthus about 20 cm apart to make room for the dense foliage that is produced during the first season. The flowers will self-seed at the end of the growing season, providing gardeners with a fresh bunch of volunteers every spring. The plants themselves usually die off after a couple of years, so take advantage of its tendency to produce plenty of seeds to replenish your supply of fresh flowers. 

QUICK FACTS

- The exact origin of its English name is unknown but is said to honour either William Shakespeare, the Duke of York or William the Conqueror. 

- The term ‘’sweet’’ most likely comes from the distinctively fragrant clove-like and cinnamon scent of the blossoms.

- Dianthus seeds will remain viable for 2 years if stored in a cool, dark place, ideally between 4 and 10⁰C. After that, the germination rate may start to go down.