Plant Care & Growing Guide

Perennial Dianthus Care

Here are the main care requirements for growing a perennial dianthus plant:

• Requires full sun, with at least six hours of light.
• Water once a week with at least an inch of water.
• Prefers a slightly alkaline soil that is well-draining.
• Thrives from 40 F to 85 F; otherwise, the plant will enter dormancy.
• Plant in compost-enriched soil; doesn’t need fertilizer.

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

If the soil in your dianthus plants doesn’t drain well, stem rot can be a problem. Consider containers or raised beds for your plants if your garden’s soil is heavy clay.

Dianthus plants like a neutral to slightly alkaline soil pH. If your soil pH is below 7.0, correct the acidity by applying 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 prevent 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 don’t need much traditional fertilizer. A shovelful of compost worked into the soil once a year nourishes the plants.

Types of Perennial Dianthus

Perennial dianthus varieties are native to Europe, Asia, and Africa. They feature lovely, colorful, and fragrant flowers. Some of the most common types include:

• D. deltoides ‘Arctic Fire’: A varietal that features a contrasting “eye” (center) more commonly found in biennial varieties
• D. gratianopolitanus ‘Firewitch’: A hot pink varietal that has been in cultivation since 1957
• D. ‘First Love’: A varietal that may have white and pink blossoms at the same time and often boasts repeat blooms
• D. plumeria ‘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. In the fall, prune back the plant until only 1 to 2 inches of stem remain 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, ensuring that the new plants have the same characteristics as the parent plant. To propagate by cutting, follow these steps:

1. Take a 2- to 3-inch cutting from an established mother plant that has bloomed for at least a full season. Cuttings should be taken in June or July after the plant has bloomed for the season.
2. Combine potting soil with vermiculite in a small pot—the mixture should be moist but not damp or soggy.
3. Dip the cut end of the cutting in a rooting hormone.
4. Plant the cutting into the potting soil, ensuring at least one node falls beneath the soil line.
5. Place the pot in a warm, sunny location.
6. Keep the soil moist—the cutting should take root within a month.
7. Once you spot new leaf growth, you can transplant the cutting and care for it as usual.

How to Grow Perennial Dianthus From Seed

Dianthus plants are easy to grow from seed, but there is no guarantee that the resulting plants will mirror that of the parent plant. 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 fully bloom in under three months.

1. Sow seeds in a seed tray indoors eight weeks before the final frost in your area. Place the seed on the soil surface and cover it lightly with soil. The seeds need light to germinate.
2. Situate the seed tray somewhere warm and sunny until the seedlings germinate, which should happen in approximately eight to 10 days.
3. Grow the seedlings indoors until they reach 4 inches tall. Once all risk of frost has passed, they can be planted outdoors.

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 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.

Dianthus plants are resistant to deer, though the same can’t be said for rabbits.

How to Get Perennial Dianthus to Bloom

Bloom Months

Dianthus blooms emerge in May through part of the summer, usually slowing down during peak heat. Blooms are heaviest in late spring, with some possible rebloom into fall once the high temperatures ease.

What Do Dianthus Flowers Look and Smell Like?

Dianthus blooms may be single or double, but all have the same jagged-edged petals. The flowers are five-parted and fragrant in pink, pink-purple, or white. They have a sweet, spicy scent with cinnamon and clove undertones.

Dianthus plants feature handsome bluish-grey foliage that is showy in its own right when the plants are not in bloom. The narrow, grass-like foliage may exhibit a mounded, erect shape, or trailing habit.

How to Encourage More Blooms

Dianthus plants are easy to care for and rarely have trouble blooming, but to encourage more blooms, you can do a few things:

• Give ample light: Dianthus plants should be planted in a location with at least six hours of bright sunlight daily. Too little light can impact the frequency and vibrancy of the blooms.
• Give more water: Ample water is essential for dianthus plants’ overall health and blooming. Frequent weekly watering ensures that the soil doesn’t dry out. You can also mulch over the soil around the plant’s roots to lock in moisture and prevent evaporation.
• Deadhead: Frequently deadheading the spent blooms invites the plant to ensure a second bloom later in summer or early in the fall by producing more buds and foliage rather than putting energy into turning the spent flowers into seeds.

Common Problems With Perennial Dianthus

Dianthus plants are easy to care for but a it can occasionally have a few problems.

Yellowing or Failing to Thrive

If your dianthus appears to be yellowing or dying, this dormancy behavior is natural during periods of high heat and when temperatures start to drop. Overwatering can also cause leaves to start yellowing. Ensure the soil is moist but not soggy.

Brown, Crispy Leaves

Plants that are underwatered can develop brown, crispy, or curled leaves. The leaves and stems may also start to become floppy.