Native to Europe, Asia, and Africa, dianthus plants feature handsome bluish-grey foliage that is showy in its own right when the plants are not in bloom. The foliage is narrow—even grass-like—and plants may exhibit a mounded shape, an erect habit, or a trailing habit. When choosing varieties of dianthus for your landscape, don’t be confused by the name “pinks.” While many varieties do have pink flowers, this nickname comes from the fringed edges of the flower petals. Dianthus plants grow fast and are best started in the spring after all risk of frost has passed. Seedlings can emerge in as little as eight days, and a new plant can be fully in bloom in under three months. Blooms are heaviest in late spring, with some possible rebloom into fall. Dianthus blooms may be single or double, but all have the same jagged-edged petals. All dianthus plants are toxic to pets. The mounding shape and long blooming time of dianthus plants make them welcome additions to any container garden. In garden beds, place dianthus at the front and along borders so you can appreciate their pleasant clove fragrance. You can also add dianthus plants to a butterfly and hummingbird garden, as the flowers attract both with their nectar. Another option is to include dianthus in an alpine or rock garden, where they thrive in the fast-draining soil. Dianthus plants are resistant to deer, though the same can’t be said for rabbits.
Light
Full sun is important for thriving plants, so choose a location that gets at least six hours of light each day. Plants that don’t get enough light can see a reduction in blooms or flower vibrancy.
Soil
Stem rot can be a problem in dianthus plants if their soil doesn’t drain well. If the soil in your garden is heavy clay, consider containers or raised beds for your plants instead. Additionally, dianthus plants like a neutral to slightly alkaline soil pH. If your soil pH is below 7.0, correct the acidity with an application of dolomitic limestone (fireplace ashes can also increase soil alkalinity). It’s fine to use mulch to keep weeds under control but avoid letting the mulch crowd around the crowns of dianthus to avoid rot.
Water
Dianthus flowers need weekly watering. Aim to give plants 1 inch of water per week, but avoid water-logging the soil.
Temperature and Humidity
These plants can tolerate a light frost but don’t like a deep freeze. If temperatures will be dipping below 40 degrees Fahrenheit, cover plants with a frost blanket to protect them. The flowers can also go dormant in consistently hot summer temperatures above 85 degrees Fahrenheit.
Fertilizer
Dianthus plants are light feeders and won’t need much in the way of traditional fertilizer. A shovelful of compost worked into the soil once a year is enough to nourish the plants.
Types of Perennial Dianthus
There are several perennial dianthus varieties with lovely colorful and fragrant flowers. Some of the most common include:
D. deltoides ‘Arctic Fire’: A varietal that features a contrasting “eye” (center) more commonly found in biennial varietiesD. gratianopolitanus ‘Firewitch’: A hot pink varietal that has been in cultivation since 1957D. ‘First Love’: A varietal that may have white and pink blossoms at the same time and often boasts repeat bloomsD. plumarius ‘Rose de Mai’: A very fragrant heirloom varietal with lilac flowers, often used in perfumes
Pruning Perennial Dianthus
Properly pruning your dianthus plants can help increase the chance of repeat blooming and keep the plant tidy throughout the year. Flowers should be deadheaded once spent, especially on varietals known for repeat blooms. Throughout the year, remove any stems or leaves that look diseased or damaged. Come fall, prune back the plant until there are only 1 to 2 inches of stem remaining above the soil. The plant will go dormant for the season and regrow the following spring.
Propagating Perennial Dianthus
While dianthus plants are more readily started from seed, they can also be propagated using stem cuttings, which will assure that the new plants will have the same characteristics as the “mother plant.” To propagate, follow these steps:
How to Grow Perennial Dianthus From Seed
Dianthus plants are easy to grow from seed, but there is no guarantee that the plants that result will mirror that of the “parent” blooms. To grow from seed, plant into a seed tray indoors around 8 weeks before the final frost in your area. Keep the seed tray somewhere warm and sunny until the seedlings germinate, which should happen in approximately eight to 10 days. Continue to grow the seedlings indoors until they’ve reached 4 inches tall. They can be then planted outdoors once all risk of frost has passed.
Common Pests and Plant Diseases
One of the biggest issues dianthus plants have is vascular wilt. Characterized by dull green stems that droop and eventually dry out, wilt is technically a fungus that can eventually kill an entire plant. Treatment is difficult as fungicides are not effective—therefore, it’s important to rotate your plantings frequently and avoid planting in any soil that seems diseased. Additionally, dianthus plants may have issues with other common plant pests, such as spider mites and aphids. To treat, you can apply insecticidal soap or neem oil until all signs of an infestation are gone.
How to Get Perennial Dianthus to Bloom
Lucky for many gardeners, dianthus plants are easy to care for and rarely have trouble blooming. Still, if you’re having trouble getting your plants to show off, there are a few things to keep in mind. First and foremost, dianthus plants should be located somewhere that gets at least six hours of bright sunlight daily. Too little light can impact the frequency and vibrancy of the blooms. Additionally, ample water is important for the overall health and blooming of dianthus plants. Ensure that the soil doesn’t get dried out with frequent weekly watering—you can also mulch over the soil around the roots of the plant to lock in moisture and prevent evaporation. Finally, proper grooming is essential to encouraging dianthus plants to bloom. By frequently deadheading the spent blooms, you’ll invite the plant to produce more buds and foliage, rather than put energy into turning the spent flowers into seed.
