By: Bonnie L. Grant, Certified Urban Agriculturist
Dianthus flowers (Dianthus spp.) are also called “pinks.” They belong to a family of plants which includes carnations and are characterized by the spicy fragrance the blooms emit. Dianthus plants may be found as a hardy annual, biennial or perennial and most often used in borders or potted displays. A quick tutorial on how to grow dianthus reveals the ease of care and versatility of this attractive flowering plant.
The dianthus plant is also called Sweet William (Dianthus barbatus) and has a fragrance with cinnamon or clove notes. The plants are small and usually between 6 and 18 inches (15-46 cm.) tall. Dianthus flowers are most often in pink, salmon, red and white hues. The foliage is slender and sparsely spread on thick stems.
Dianthus had a short blooming season until 1971, when a breeder learned how to grow forms that did not set seed and, therefore, had a prolonged their bloom period. Modern varieties will typically bloom from May to October.
Plant pinks in full sun, partial shade or anywhere they will receive at least 6 hours of sun.
The plants need fertile, well-drained soil that is alkaline.
Wait until the danger of frost has passed when planting dianthus and place them at the same level they were growing in the pots, with 12 to 18 inches (30-46 cm.) between the plants. Do not mulch around them.
Water them only at the base of the plant to keep the foliage dry and prevent mildew spotting.
Instructions on how to care for dianthus are very straightforward. Water the plants when dry and apply fertilizer every six to eight weeks. You may also work a slow-release fertilizer into the soil at planting, which will release you from the need to feed the plants.
Some varieties of dianthus are self-sowing, so deadheading is extremely important to reduce volunteer plants and to encourage additional blooming.
Perennial varieties are short lived and should be propagated by division, tip cuttings or even layering. Dianthus seed is also readily available at garden centers and may be started indoors six to eight weeks before the danger of frost has passed.
There is a dianthus plant for almost any garden space and region. The typical annual dianthus is the Dianthus chinensis, or Chinese pinks.
The perennial varieties include Cheddar (D. gratianopolitanus), Cottage (D. plumarius) and Grass pinks (D. armeria). The foliage on all of these is blue-gray and each comes in a rainbow of colors.
D. barbatus is the common Sweet William and a biennial. There are both double and single flowers and the variety reseeds itself.
Allwood pinks (D. x allwoodii) are long lasting with flowering extending at least 8 weeks. They are mostly double flowering and come in two sizes, 3 to 6 inches (8-15 cm.) and 10 to 18 inches (25-46 cm.) tall.
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Most varieties are hardy in U.S. Department of Agriculture plant hardiness zones 3 through 9 and come in shades of pink, red, white or bicolor. The flowers have a spicy scent and make excellent cut flowers. Pinks are classified as tender perennials. They generally begin to languish after two or three years. Some varieties will self-sow and you can extend their life by taking small cuttings or plugs.
Dianthus has long been beloved in Britain, where it was probably introduced by the Normans a millennia ago. Rochester Castle in Kent has a patch of dianthus growing on the castle wall that has possibly been there since the castle was built in 1100.
Dianthus is a genus of flowers that covers a lot of ground, so to speak. In addition to common garden pinks (the low-growing, candy-colored cultivars we most often associate with Dianthus, the taxonomic category includes carnations and sweet William (a species of pink that somehow managed to get its own horticultural nickname).
But don’t be confused. All kinds of Dianthus are useful garden flowers, with attractive grayish green foliage and adorable, starry blossoms. Carnations can be ruffled, pinks are often frilly, and sweet William is in a class by itself with its tightly packed balls of blooms.
Depending on the species and cultivar, Dianthus can be an annual, a tender perennial, or a biennial (looking at you, sweet William). But even in warmer growing zones (6 and higher), these are short-lived perennials and you probably won’t get more than two seasons of flowers out of them before they start to look scraggly. Replace them with impunity to keep a steady supply of flowers spilling over the front of the border of the edge of a path.
For some of our favorite varieties of pinks, see Gardening 101: Dianthus, for a closer look at D. alpinus (a delicate rock garden flower), D. plumarius (the one you think of when you close your eyes and envision pinks), and D. ‘Mrs. Sinkins’ (Vita Sackville-West’s favorite).
For more growing tips, see Dianthus: A Field Guide to Planting, Care & Design in our curated guide to Annuals 101. Read more:
Plant dianthus in full sun for best blooms from nursery transplants, divisions or cuttings. The plants prefer slightly rich, reasonably moist soil that is well-draining and alkaline. Dig 2 inches of compost into the soil before planting and add lime if your soil’s pH falls below 6.0. In soggy soils, the plants develop root rot. You may notice blackened stems and the plants fall apart.
Dig holes as deep and twice as wide as the young plants and space them 12 inches apart. Water the plants frequently during the first four weeks after planting to keep the soil consistently moist. Once the plants begin to show new growth, cut back watering so the soil stays slightly moist 2 inches beneath the surface. In general, watering once a week should suffice, although you might need to water more frequently during hot weather. If the plants sit next to an irrigated lawn, you probably won’t need to water as much.
Remove the flowers after they’re spent to encourage more blooms. Shear the plants back by one-third mid-summer. This practice keeps them looking tidy and encourages new growth and flowering. Dig the plants up every two years to divide them or cut off small pieces from the edges for new plantings. In this way, you can extend the life of your planting for many years.
Fertilize dianthus lightly in the spring with ¼ cup 10-10-10 fertilizer for every 20 square feet of garden space. Mulch the soil with 2 inches of wood chips or bark to conserve moisture and keep weeds down. Cut the plants to 3 inches above the ground after the first frost.
Softwood tip cuttings taken from your Dianthus plants in the spring or in early summer
will be ready to be planted in the garden by fall.
However, plants grown from cuttings will not flower until the following year.
Dianthus are easily propagated by digging and dividing established clumps.
Dividing your Dianthus plant has the additional benefit of rejuvenating older, non productive clumps.
Dig up an entire Dianthus clump and either pull it apart using your hands to separate the plant segments.
You can also use two gardening forks inserted in the center of the clump to gently pry the plant apart.
Replant each new division as you would a new perennial or annual, and water it in very well.