Carnations, sweet william, pinks! There’s such a wide diversity of dianthus plants out there, all of which are beloved by gardeners for their frilly flowers and their green foliage.
But with all this variety, how do you take care of them? Are there diseases or pests that are likely to prey on your plants, and most importantly, is deadheading really necessary?
I’ll answer all these questions and tell you how to keep these amazing plants thriving in your yard.
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|Common Name(s)||Carnations, pinks, clove pink, Sweet William, Green Trick Dianthus, maiden pink, Dianthus Kahori, Zing Rose, Deptford pink, grass pink, mountain pink, common pink, garden pink, wild pink, Cheddar pink, grandiflorus, Dianthus Firewitch, alpine pink, Joan’s Blood, and many more|
|Scientific Name||Dianthus caryophyllus, Dianthus barbatus, Dianthus armeria, Dianthus deltoides, Dianthus plumarius, Dianthus gratianopolitanus, Dianthus alpinus and many more|
|Origin||Originated throughout Europe & Asia, now worldwide|
|Height||From 10” to 3’ depending on variety|
|Water||Water at base of plant regularly|
|Temperature||Cold-hardy but prefers between 50-80 degrees|
|Humidity||Can tolerate humidity, but watch for diseases|
|Soil||Rich, well-drained soil with lots of compost blended through|
|Fertilizer||Regular compost applications or a 5-10-10 slow-release fertilizer|
|Propagation||By cuttings, division, or seed.|
|Pests||Aphids, spider mites, cutworm, cabbage moth. Also a host of plant diseases.|
Types of Dianthus
There are over 300 species of dianthus, and thousands of cultivars have been bred from those species. In hues of yellow, red, pink, and white, dianthus flowers are widely popular. Here’s a few of the basic species from which many cultivars have been bred, and some detail about those species!
Dianthus caryophyllus, ‘Carnation’, ‘Clove Pink’
The Royal Horticultural Society has given quite a number of different carnations its prestigious Award of Garden Merit, and for good reason. The carnation has become one of the most popular flowers in the world. The state flower of Ohio is a cultivar of dianthus caryophyllus. It’s the national flower of Spain, Morocco, and Slovenia as well.
The natural color of carnations is a pinkish-purple, but they’ve been cultivated to produce multiple other shades from true pink through reds, yellows, whites, and even green. There are a few crossbreeds with other plants that produce bluish-shaded flowers as well, although no true carnation can naturally produce a blue tone on its own.
Dianthus barbatus, ‘Sweet William’, ‘Green Trick Dianthus’
Sweet William is a popular garden plant, and it’s easy to see why. These flowers are beautiful! In the wild, they produce red flowers with a white base, but multiple cultivars have provided not just variations on color, but variegated patterns. In addition, the green trick dianthus produces bright green round blossoms instead of the normal ruffle-edged flower pattern. Dianthus barbatus is definitely a keeper!
Dianthus deltoides, ‘Maiden Pink’, ‘Dianthus Kahori’, ‘Zing Rose’
Another Award of Garden Merit winner, the Kahori cultivar of the maiden pink is incredibly beloved for its showy pink flowers on a rich green base. Other maiden pinks range from a pale hue to the vibrantly-bright tone of the Zing Rose cultivar shown above. It’s easy to see why these are popular!
Dianthus armeria, ‘Deptford Pink’, ‘Grass Pink’, ‘Mountain Pink’
The Deptford Pink is yet another award-winning cultivar of dianthus. These speckled, serrated petals form a little star shape that practically pops out of the garden at you. Other mountain pinks are available in 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, ‘Common Pink’, ‘Garden Pink’, ‘Wild Pink’
These plants are quite a show-stopper with their jagged edges and bright blooms! Often seen in both wild and cultivated landscapes, this ‘common pink’ is far from common in terms of its looks. Variegated colors are available, as well as single-color cultivars, but regardless of which you choose, you’ll have a miniature floral fireworks display at all times.
Dianthus gratianopolitanus, ‘Cheddar Pink’, ‘Grandiflorus’, ‘Dianthus Firewitch’
Yet another winner of the RHS’s Award of Garden Merit. Similar in flower shape to dianthus plumarius, the Cheddar pink is not named after cheese, but after the town in the UK where it was cultivated. Its flowers are fragrant as well as beautiful, and it adds a lot of color to the garden. The Firewitch cultivar is especially loved for its striking shade.
Dianthus alpinus, ‘Alpine Pink’, ‘Joan’s Blood’
If you can’t tell, the Royal Horticultural Society loves dianthus, as this is one more winner of the Award of Garden Merit. The Joan’s Blood cultivar is especially beloved. This smaller dianthus isn’t quite a dwarf species, but it does have a more compact growth pattern and tends to have smaller flowers.
While starting out might seem to be tricky, dianthus are actually quite easy plants to care for. Making sure that they have the right environment for growth is important. Read on to learn how to care for dianthus properly.
Full sun is ideal for most dianthus species. They can tolerate part-sun conditions as long as they get at least six hours of sun, but the flowers may be slightly less vibrant. If partial sun is the only choice available, try to allow them to be shaded during the hottest part of the day.
Watering should only be done at the base of the plant to keep the foliage dry. This helps to prevent mildew from forming on the leaves. Dianthus does not like to be overwatered, so be sure that there is no standing water around your plants.
Well-drained soil is essential for growing all dianthus plants, as they really don’t like to be overly wet. They prefer richer soils or soils with lots of compost worked in. 2-4 inches of compost worked through the top foot of soil prior to planting is perfect, with regular re-applications around the top of the plant.
Prior to planting, it’s good to mix a slow-release fertilizer into the soil in addition to the compost if you’re trying to stimulate flowering. A higher potassium level fertilizer will encourage lots of color. 5-10-10 slow-release granular fertilizer does well for most types of carnations and pinks. If you opt to use a liquid fertilizer, reapply every 4-6 weeks to encourage additional flowering.
Propagation By Cuttings
There are three ways to propagate dianthus plants: by cuttings, by division, or by seed.
Propagation by cuttings is the most common, as it ensures that the new plant has the same characteristics as its parent plant. Your cuttings should be taken in either June or July, after a thorough watering the day before and ideally on an overcast day to reduce shock to the parent plant. First, fill some small pots with a 50/50 mix of horticultural sand and vermiculite.
Examine your existing plant and select your cutting. It should have several well-developed leaf nodes. Cut about 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 carefully set the cutting into it, easing more of the planting medium around to support the cutting and keep it upright. Keep your cutting moist and in a sunny location until the roots form and new leaf growth has formed. You can use a dome to help keep it humid around the plant.
Propagation By Division
As a dianthus plant gets older, it will form large, spreading mounds that gradually creep outward. You can divide these every few years to create more plants. Before you begin, water the plant well the day before to help 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.
Propagation By Seed
Although dianthus will easily start from seed, the seedlings do not always share the same characteristics as the parent plant. Because of this, it’s best to start with purchased seed from a quality seed vendor. Make a growing medium of three parts potting soil, one part peat moss, two parts compost, and one part horticultural sand, and mix well. Fill your starter trays or starter pots with this mix, and then gently sprinkle seeds on the surface. Take care, as the seeds are quite brittle along their edges! Cover lightly with 1/8″ of your growing medium, mist with water, place in a sunny location and keep the plant moist until your seeds germinate (8-10 days). Transplant once your seedlings are 3-4 inches tall.
The night before repotting, water your plant thoroughly to help prevent transplant shock. Prepare the soil in your new pot or location, being sure to work a couple inches of compost throughout the soil. Add a slow-release granular fertilizer if you wish, then carefully remove your dianthus from its old pot. You do not want to plant it deeper than it was originally planted, as that can cause growth issues. Set it into place in its new pot, then carefully fill around the base of the plant with soil, and water it in.
Dianthus can tolerate some pretty harsh treatment once established. Here’s how to deadhead dianthus and how to encourage new growth!
As flowers fade and begin to wilt, pinch them off just above the topmost set of leaves. This stops the plant from forming seeds, and also may encourage a new flush of growth.
Once the first flush of flowering has ended (usually early summer), use a pair of clean garden shears to prune the plant down. You can remove up to half of the plant’s height. This tells the plant it needs to bush out more and stimulates a new set of flower buds. Throughout the summer, you can then trim off any leggy or overgrown stems to keep the plant’s shape visually appealing as needed.
In the fall, dianthus will begin to die back naturally. This is normal, so don’t panic! Trim the plant back to 1-2″ above the soil level and remove the old foliage. It will overwinter and start a fresh flush of growth in the spring.
One of the biggest problems for many is that their young seedlings die quickly and inexplicably. This is usually caused by a lack of moisture. Some dianthus species really require higher humidity to properly develop. This can be remedied by checking the status of the plant regularly, and misting it with a spray bottle. However, try to hold the spray bottle far enough away that the tender seedling doesn’t get blown around with the force of the spray, and so the mist will settle much like a fog might.
In addition, a number of pinks tend to self-seed rapidly. While this doesn’t seem like an issue, if you want flowering plants, it certainly can be! Deadheading your pinks aggressively once the flowers fade will help stop the plant’s progression into the seed-production phase and cause it to flower again. If left unchecked, the plants will spread seed everywhere and you’ll start finding volunteer plants scattered all over your yard.
Most of the pinks family has issues with the following four pests, all of which can be easily combatted using traditional measures.
Any cutting insect is an issue for dianthus. Cutworms are especially notable, but the cabbage moth can also be an occasional problem. For both of these, using bacillus thuringiensis, or BT, will successfully kill off any interlopers. I recommend Monterey BT, a liquid application which can be lightly misted onto the plants to repel cutting insects.
If you’re seeing superfine webs building up on your plants and you’re noticing brown or white spotting, you are seeing the 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.
Aphids are also a problem as they will literally suck the life out of your plant. In this case, neem oil is also beneficial. If you are finding that you have regular issues with aphids and spider mites elsewhere in your garden, you may wish to proactively spray plants that are in danger with a light misting every few days to once a week, just to keep these pests away.
Dianthus is susceptible to a number of different plant diseases. Some of these are fungal, others are bacterial.
Two fungal wilts, fusarium wilt and verticillium wilt, are particularly troublesome. These are soilborne fungal infections, and unfortunately, plants which have been impacted by these wilts should be removed and destroyed so as to not spread the infection further. In addition, you should avoid planting more dianthus in those locations until the fungus in the soil has died off. Look for plants which are resistant to those wilts.
There is also a bacterial wilt caused by psuedomonas. This is also non-repairable. As this bacteria can easily spread, it’s important to sterilize your tools after removing plants that have been impacted by wilts using either rubbing alcohol or bleach to clean them thoroughly. These plants should also be destroyed.
Root rots and crown rots can also be an issue. These can cause the plant to wilt and look generally droopy, and in time can cause browning or yellowing of the leaves and slowly progress on towards plant death. Avoid overwatering, and don’t water from above, only at the soil level. If you see the symptoms of a root or crown rot in your plant, it may already be too late, so prevention is important.
Both septoria leaf spot and alternaria leaf spot are regular diseases. These can be combatted with an antifungal spray such as Bonide Fung-Onil Fungicide, and it is also best if you remove leaves that you find that show signs of leaf spot diseases to help slow the progress. It’s important if you’re seeing leaf spot to water only early in the morning, which allows the plant’s foliage to dry before the sun sets.
If your flowers start to turn a papery brown and begin to develop grey, fuzzy masses, you are experiencing botyris flower rot. This is generally a problem during cloudy and humid or wet weather. Treat with a fungicide such as Bonide Fung-Onil and be sure to deadhead your spent flowers rapidly for a while to prevent further spread. Trim back any leaves which show signs of tan to brown streaks as well, as those are also susceptible to the flower rot.
Frequently Asked Questions
Q: Is dianthus annual or perennial?
A: That really depends on where you’re at. In areas like California it’s often a short-lived perennial, but it doesn’t tolerate hard freezes well. It can handle light frosts like a champ, though! If you opt to place a cold frame over your plant in the wintertime, it can likely act as a perennial even in colder environments. It is a very hardy annual otherwise.
But more importantly, it depends on the individual species of dianthus. Some dianthus plants are very strong perennials and have a tendency to self-seed if you don’t deadhead them quickly, causing them to spread rapidly. That’s in part why pinks are so commonly used for meadow restoration in parts of the world. With more than 300 varieties of dianthus, there’s going to be at least a few which you can grow no matter where you’re at.
Q: How big does dianthus get?
A: Again, it depends on the variety you get. While some, like sweet william, will stay in the 10-15″ range, others will grow to be 2-3 feet tall. Generally speaking, it’s best to check your plant information or the back of the seed packet for its anticipated size before purchasing, just to be sure you have the right space prepared for your plant.
Whether you’re trying to grow a pot of pinks, a cluster of carnations, or a wealth of Sweet Williams, you should incorporate dianthus into your garden just for its bright and showy color. What’s your favorite species? Tell me in the comments below.
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