How to Plant, Grow, and Care for Dianthus

The best thing about dianthus is you’ll find tons at your local nursery. Each variety is similar but different enough that you have choices. How you incorporate this easy-going variety into your landscape informs the type you choose. 

They aren’t native to North America, but they’re lovely and provide pollen for insects who stop off at your dianthus flowers as well as your pepper flowers, too. With over 300 species to choose from, chances are there’s one you’ll enjoy. 

In this piece, we’ll discuss caring for dianthus. We’ll identify some of the 300+ plus varieties, talk about dianthus care, and cover issues that dianthus gardeners might run into. After you’re done reading this, you’ll be fully equipped to add a dash of dianthus to your garden. 

What are Dianthus?

Dianthus (Dianthus spp.) is a genus of flowering herbaceous perennials, though some are annual or biennial. Some develop woody stems and a shrub-like growth habit. Dianthus flowers are hardy while they’re growing. They’re popular in floral arrangements. They’re perfect in a perennial garden, alongside annual vegetables, and in cottage gardens, too.

Native Area

They were named by the Greek philosopher Theophrastus in the 300s BC. Dianthus is native to Europe and Asia, with a few species hailing from Africa. They also have a history of use in Chinese, Japanese, and Korean medicine to treat mouth and gum diseases, as well as gastrointestinal conditions. 

Characteristics

All dianthus species have opposite leaves that are simple and green. They reach 10 inches tall to 36 inches tall, and one to two feet wide, depending on the variety. The sometimes-double flowers have five petals and come in arrays of colors and scents. Common varieties have frilled pink to fuschia petals that bloom from early spring to late fall. All self-seed or return annually. Their long roots remain in the soil throughout harsh winters. 

Varieties

Today, you’ll find some species of dianthus at your local nursery. Let’s discuss some of the most common species out there, so you can make your decision and grow perennial dianthus. 

Dianthus caryophyllus

The national flower of Spain, Monrovia, and one species is the state flower of Ohio. Commonly called carnation, clove pinks, carnation Pinks, red dianthus, their natural color is pinkish-purple. People have been growing carnations to select multiple shades: true pink, reds, yellows, whites, and even green. Some crossbreeds produce bluish-shaded flowers, although no true carnation can naturally produce a blue. The dianthus flower of the carnation is ruffled and light pink, to almost lavender. They thrive in cooler USDA zones and bloom from spring to summer.

Dianthus barbatus

Sweet William, or green trick dianthus, is a popular garden choice. In the wild, they produce red flowers with a white base. Multiple cultivars of sweet Williams have variations in color and pattern.

Dianthus deltoides

Kahori dianthus are beloved for their showy pink flowers. They are also called maiden pink or dianthus kahori. Other maiden pinks range from a pale hue to the vibrantly-bright ‘Zing Rose’ cultivar.

Dianthus armeria

Deptford pink, grass pink, mountain pink or sand pink are some of the common names for this variety. Speckled, serrated, frilly petals form a little star shape. Other mountain pinks have a mix of colors. These are used in parts of the world for wild meadow recovery but also look stunning in a garden environment.

Dianthus plumarius

These are called common pink, garden pink, wild pink or cottage pink. Jagged edges and bright blooms of garden pinks are both wild and cultivated. Common pink is far from common with variegated colors and single-color cultivars. These have the most stunning sweet fragrance of the dianthus family.

Dianthus gratianopolitanus

Other names for this dianthus species include cheddar pink, grandiflorus and Dianthus ‘Firewitch’ Similar shape to Dianthus plumarius, cheddar pinks are named after the town in the UK where they were cultivated. Cheddar pinks’ flowers are fragrant and beautiful, and their lovely blue-green foliage cools the landscape. The ‘Firewitch’ cultivar is loved for its striking shade.

Dianthus alpinus

The ‘Joan’s Blood’ cultivar of the alpine pinks species is highly admired. Alpine pinks are smaller dianthus pinks that aren’t quite a dwarf species but have compact growth and smaller flowers.

Dianthus chinensis

China pink blooms are great for cool-weather growers. This dianthus perennial blooms from late spring to early summer. The flowers are deep pink and white, with a dark pink center.

Planting

Choose either a large container with well-draining soil or a spot in full sun for planting dianthus. Dianthus are great cottage-style types and also do well in a cutting garden or in rock gardens. If you’re working with transplants, dig a hole slightly wider than the nursery pot and just as deep. Set your perennial dianthus or sweet William, so the crown is in line with the soil level. Then, cover them with fresh soil and water them in. 

To plant dianthus seeds, find a full sun area with well-drained soil, and wait until the last spring frost has passed. Alternatively, plant 12 weeks before the first frost in fall. Sow the seeds evenly on the soil surface and lightly cover them with fine soil. Water them in. In about a week, they’ll germinate. When the seedlings have two to three leaves, thin them to eight to twelve inches apart.

How to Grow

Once you’ve planted your dianthus among other cottage-style varieties or in planters, you’ll need to properly care for them. Let’s discuss the basic needs for mass plantings and mounding perennials alike. 

Light

Full sun is ideal for most species. They can tolerate partial shade as long as they get at least six hours of light per day. Too much shade may make flowers less vibrant. Members of the dianthus genus are hardy in zones 3 to 9.

Water

Water at the base of your dianthus to keep the foliage dry. This prevents mildew from forming on the lovely blue-green foliage. Dianthus does not like wet feet, so eliminate standing water around them. Water in the morning or at dusk with soaker hoses, drip irrigation, or a watering can. Give your dianthus at least one inch of water per week. I’ve found my well-established and well-mulched dianthus can handle less water than that. In times when there is ample rain, there’s no need to add more water. 

Soil

When it comes to dianthus, where to set it is an important question. Well-drained soil is essential to grow dianthus. They prefer rich soils or those with lots of compost worked in. Two to four inches of compost worked through the top foot of your garden beds prior to planting is perfect, with regular re-applications around the top in early spring before new growth begins. Sandy soil is best for your dianthus as long as it contains ample nutrients. They prefer acidic soil over alkaline soil, with a pH of 5.5 to 5.8.

Temperature

Dianthus isn’t a fan of very cold winters, and sometimes a light frost will cause it to die back. However, a thick layer of organic mulch not only helps suppress weeds but keeps the roots alive during even hard freezes and consistently freezing winters. In snap freezes of early autumn and early spring, cover your dianthus with leaves or with a shade cloth to keep new plants safe in extreme weather.

Most go dormant in temperatures above 85°F (29°C), but some of these flowering varieties continue to produce in hot weather.

Fertilizing

Prior to planting, mix a slow-release organic fertilizer into the soil in addition to compost if you want to stimulate flowering. Higher potassium levels in fertilizer encourage lots of color. Slow-release granular fertilizer is great for most types of carnations and pinks. For a balanced fertilizer in liquid form, reapply every four to six weeks to encourage additional flowering. Standard liquid fertilizers encourage deep rooting, whereas higher amounts of phosphorous and potassium encourage additional blooming and a longer bloom time. 

Maintenance

You may wonder how to deadhead dianthus. Pinch off spent blooms just above the topmost set of leaves. This stops it from forming seeds and also may encourage a new flush of growth and extend the bloom time. Once the first flush of flowering has ended (usually early summer), use a pair of clean garden shears or pinking shears to prune it down. Remove up to half of the height. This tells your dianthus they need to bush out more and stimulates a new set of flower buds.

Throughout the summer, trim off any leggy or overgrown stems to keep the shape visually appealing. Continuously remove spent flowers to prevent spreading and seeding. Or leave them if you want more dianthus flowers next year. In the fall, dianthus dies back naturally. Trim your dianthus plants to one to two inches tall and remove the dead foliage or evergreen foliage, depending on the variety. They’ll overwinter and start a fresh flush of dark green foliage in the spring.

Water thoroughly the night before repotting to prevent transplant shock. Prepare the soil in your new pot or location, working a couple of inches of compost throughout the soil. Add a slow-release granular fertilizer if you wish, and then carefully remove your dianthus from its old pot. Do not plant it deeper than it was originally planted, as that can cause growth issues. Set it into place in its new pot and carefully fill around the base of the plant with soil. Water it in, then wait for dianthus flowers and new blue-green leaves to emerge. 

Propagating

Propagation by stem cuttings ensures the dianthus has the same characteristics as its parent. Take cuttings in June or July after watering the day before. Propagate on an overcast day to reduce shock to the parent.

First, fill some small pots with a 50/50 mix of horticultural sand and vermiculite. Your cutting should have several well-developed leaf nodes. Cut a quarter-inch below a leaf node, and dip the cut end, including the leaf node, into rooting hormone powder. Then, with a pencil or stick, make a hole in your starter medium and set the cutting into it, easing more of the planting medium around to support the cutting and keep it upright. Keep the soil moist and in a sunny location until the roots form, and new green foliage has formed. Use a dome to keep the cutting humid.

As dianthus gets older, it becomes mat-forming, gradually creeping outward. Divide these every few years in early or late spring to grow dianthus in new areas. Water well the day before to reduce transplant shock. Then, gently dig up the dianthus and use your fingers to separate off three to six-inch segments. Replant these in prepared soil and water again to help them to settle into their new place. You’ll find the most success with perennial dianthus when it comes to this method. Generally, hardy perennials will have the easiest time getting established and flourishing.

Common Problems

Now that we’ve covered care for dianthus let’s talk about issues you may encounter. While there are plenty of pests and diseases to look out for, you may not have to deal with them at all. 

Growing Problems

One of the most common growing problems is when young seedlings die quickly and inexplicably. This is usually caused by a lack of moisture. Some dianthus require higher humidity to develop properly. Remedy this by checking the status regularly and misting it with a spray bottle. Hold the spray bottle far enough away that the tender seedling doesn’t bend with the force of the spray, and so the mist will settle much like a fog.

Pinks self-seed rapidly. Deadheading your perennial aggressively once the small flowers fade stops the seed-production phase. If left unchecked, dianthus perennials spread seed everywhere, and you’ll find volunteers scattered all over your yard.

If your bloom time is short, check to ensure you didn’t choose pinks or a short-lived perennial as opposed to a mat-forming variety that has a limited bloom time. Short-lived perennial dianthus, like sweet William or old-fashioned pinks, is great in cut flower arrangements instead of flower beds as opposed to garden pinks. 

Pests

Any cutting insect is an issue. Cutworms are especially notable, but the cabbage moth is an occasional problem. For both of these, use Bacillus thuringiensis or Bt spray to kill off any interlopers. I recommend a liquid application lightly misted onto the leaves to repel cutting insects.

Superfine webs ith brown or white spotting are signs of spider mite infestation. In this case, a light application of neem oil is your friend, again applied via a gentle misting. Neem oil will repel the mites and kill them off. Do not spray neem in temperatures above 90°F (32°C) or during peak pollinator periods. 

Aphids suck the life out of your dianthus. Spray them with a strong stream of water and follow up with neem oil to prevent further infestations. Regular issues with aphids and spider mites may warrant a regular light misting every few days to once a week, just to keep them away.

Sow bugs are much like pill bugs but not quite the same. They’re a related species and will sometimes eat dianthus when they’re in large numbers. Remove debris around your dianthus in the growing season to prevent these, and trim bottom leaves that touch the ground.  

Diseases

Fusarium wilt and verticillium wilt are soilborne fungal infections. Unfortunately, those that have been impacted by these wilts should be removed and destroyed to eliminate the spread of the infection. Avoid planting in those locations until the fungus in the soil has died off. Instead, grow fragrant flowers that are resistant to those wilts.

Bacterial wilt caused by pseudomonas is also non-repairable. Sterilize your tools after removing those that have been impacted by wilts using either rubbing alcohol or bleach to clean them thoroughly. They should also be destroyed.

Root rot, stem rot, and crown rot cause droopy flower petals, foliage, and a reduction of the spicy fragrance some offer. In time they cause browning leaves and eventually death. Avoid overwatering, and water only at the soil level. Prevention of rot is important.

Both septoria leaf spot and alternaria leaf spot may be an issue. Remove leaves that show signs of leaf spot diseases. If you’re seeing leaf spot water only early in the morning to allow the foliage to dry before the sun sets.

If your flowers turn a papery brown and develop grey, fuzzy masses, you are experiencing Botrytis cinerea flower rot. This is likely during cloudy and humid or wet weather. Deadhead spent flowers for a while to prevent further spread. Trim back leaves that show signs of tan to brown streaking.

Frequently Asked Questions