Dianthus: New Acclaim for an Old Favorite

Each year the National Gardening Bureau chooses an ornamental bedding plant to promote, and 2004 has been dubbed “The Year of the Dianthus” by that organization. The fact is Dianthus is hardly new to the gardening world. It has been a highly prized favorite of gardeners for centuries because it is (relatively) easy to grow and comes in a palette of bright colors including red, rose, lavender, pink, white and even yellow. Flowers that are bi-colored, picoteed (having petals with contrasting edges), “eyed” and streaked also are common among this popular garden plant, making it even more appealing. Add foliage that ranges from bright green to grayish-green, flowers with spicy sweet fragrance in many species and growth habit that ranges from a petite six inch dwarf suitable for edging to sturdy three foot giants suitable for borders and cuttings, and you can understand why avid gardeners get excited about this genus of plants.

Dianthus, commonly known as sweet william, pinks, maiden pink and carnation is derived from Greek words meaning “flower of the gods.” It belongs to the Caryophyllaceae family whose name is derived from the Greek for a clove tree, a reference to the above-mentioned clove-like fragrance of flowers in this family. The cultivation of Dianthus is quite ancient, dating to Greek and Roman times. Members of this genus traveled from Europe to England over the centuries and eventually found their way to colonial America, acquiring a variety of common names along the way. In addition to being planted for their ornamental value, Dianthus flowers were used for flavoring in wine, soups, sauces and jams

The genus Dianthus contains about 300 species, but only a few are considered worthy of being garden plants. The following is a description of several of them:

D. barbatus – This species is the familiar sweet william so common to old-fashioned cottage gardens. Sweet william does not refer to a person but (rather) alludes to the flower’s fragrance and a centuries-old mispronunciation of the French word for the flower: little eye or oiellet. A biennial or short-lived perennial, sweet william is winter-hardy to zone 4. It bears single and sometimes double flowers in dense clusters from late spring through summer. Plant height ranges from 5 inches to 2 feet depending upon cultivar.

D. chinensis – Commonly known as China pink, this species can be an annual, biennial or short-lived perennial, although most cultivars on the market today flower the first year and are treated as annuals. As its name suggests, this plant is native to China and tends to be short (6 to 10 inches). It produces mostly single, small scentless flowers in abundance intermittently all summer. Plants tend to be relatively carefree and do not require deadheading for continued bloom. Pink refers not to the color of the blossom but to the serrated edges of the petals, as if cut with a pinking shears. In fact, the word for the color pink comes from this flower. China pink is the most popular species of Dianthus, and plant breeders have provided us with a wide array of cultivars. All-American winners include ‘China Doll’ (1970), ‘Magic Charms’ (1974) and ‘Corona Cherry Magic’ (1993). Blooms of the latter are striking, combining solid cherry and lavender along with “tie dyed” flowers of these two colors all on the same plant.

D. chinensis x barbatus – A very common interspecific cross in this genus, this group combines the best of both species. This hybrid flowers more freely and tolerates more heat and frost than do either of the individual species serving as parents. Blooms tend to be larger and are borne in terminal clusters. Available as annuals or biennials, most flower the first year from seed if started early enough. Plant form resembles China pink more than sweet william in that they typically achieve a height of 8 to 10 inches.

D. hybrida – Members of the genus Dianthus cross-pollinate with one another quite easily, and this “species” actually represents various other interspecific hybrids. Many are thought to have D. barbatus as one parent with the other unknown. This species includes annuals, biennials or perennials and comes in a wide array of colors. Most are very free-flowering and endure heat and adverse conditions fairly well.

Lesser-known species include D. caryophyllus (carnation or clove pink), D. plumarius (cottage pink) and D. deltoides (maiden pink). The latter two are low-growing, hardy perennials suitable for edging and rock gardens, while carnation is a popular cut flower that comes in annual and perennial forms.

Most Dianthus prefer full sun and cool temperatures. This is difficult to provide in the midst of a typical Missouri summer but can be facilitated (somewhat) by giving Dianthus a bit of afternoon shade. Those Dianthus species that are annuals are cold-hardy to the point of surviving Missouri winters if given a protected location. For this reason annual Dianthus often are planted in the fall (especially in the South) and replaced in late spring before temperatures become overly hot. Dianthus also prefer soil that is slightly alkaline (pH or 7.0 or slightly above) and well-drained but moisture retentive. Dianthus are (relatively) pest free but have been known to suffer from root/crown rot in poorly drained soil. As mentioned above, dead-heading is not necessary for increasing flower production but does add to the aesthetic appeal of Dianthus.

Dianthus lends itself to many uses in the garden. Dwarf forms are popular as an edging for beds or borders and in containers. Medium-to-tall types mix well with other annuals and perennials in borders, giving good early- and late-season color in Missouri. They also are a valuable addition to any cutting garden. In the border, Dianthus combines well with other plants that complement its flower and foliage color. Coral bells, feverfew, lamb’s ear, larkspur, lavender, (perennial) geranium, petunia, poppy, (shrub) rose and sage are examples of plants that harmonize well with Dianthus.

Resource: National Garden Bureau

David Trinklein, Associate Professor, Horticulturist, UMC (573) 882-9631