Red sweet William in a spring garden.
image by H.B. Dean
Sweet William is a part of the genus Dianthus, which includes many species of annual, biennial and perennial flowers. They range in height from 6 to 18 inches tall, producing flat, round petals that are 1 inch across with fringed edges in pink, white, red or multiple colors. Sweet William are easy to grow, but require protection from poor soil, over-fertilizing and pests.
Amend the soil about one month before planting sweet William. They thrive in rich, well-draining soil. Dig up the soil and incorporate generous amounts of well-rotted compost or manure. If the soil is heavy clay, add peat moss as well.
Apply a complete plant food in the early spring, when the begin active growth begins. Be careful not to over-fertilize, as these flowers are sensitive to excess nitrogen, which can cause brown leaf tips to develop.
Protect sweet William from aphids and slugs. Spray the flowers with malathion to treat for aphids. Spread a circle of crushed eggshells or diatomaceous earth to prevent slugs from attacking the flowers.