Dianthus lusitanus (Rock Carnation)

Dianthus lusitanus, also known as Rock Carnation or Portuguese Pink, is a charming small evergreen subshrub with a compact cushion shape formed by dense grey-green stems and leaves.

As spring unfolds, delicate wiry stems emerge and elegantly culminate in lovely pink flowers that appear to be suspended in mid-air.

Dianthus lusitanus is a drought-tolerant and hardy plant native to the Iberian Peninsula, and North West Africa. 

Dianthus lusitanus plant (Rock Carnation, Portuguese Pink)

Quick Overview

TYPE

HEIGHT & WIDTH

Dianthus lusitanus height and width

BLOOM TIME

Dianthus lusitanus bloom time

SUNLIGHT

full sun

HARDINESS

hardiness (-15ºC / 5º F)

DROUGHT TOLERANCE

drought tolerance aprox 5 months

ORIGIN

prigin Iberian Peninsula and Northwest Africa

Rock Carnation Scientific name

  • Botanical name: Dianthus lusitanus  (dee-AN-thus loo-si-TAN-us )
  • Family:  Caryophyllaceae (KAR-ee-oh-fil-AY-see-ee)
  • Common name:  Rock Carnation, Portuguese Pink
NameMeaning
DianthusDerives from a combination of two Greek words “Dios” meaning divine and “anthos” meaning flower. So Dianthus means “Divine flower” or “flower of the gods”.
lusitanusDerives from Lusitania, which was an ancient Roman province located in what is now modern-day Portugal and a part of Western Spain.

How to identify Dianthus lusitanus

Dianthus lusitanus plant (Rock Carnation, Portuguese Pink)

Plant

Dianthus lusitanus is an evergreen multistemmed subshrub that forms a compact cushion. It can be considered a subshrub because the stems are often very woody at the base.

It is densely branched, and the stems are covered with fleshy greyish-green to bluish-green narrow leaves and topped with delicate pink flowers.

The plant has an average height of 10 to 15 (0.3 to 0.6 ft) 40 cm  (1.3 ft) with flower and a width of 40 to 50 cm (1.3 to 1.6 ft)

Dianthus lusitanus stem (Rock Carnation, Portuguese Pink)

Stem

The stems are greyish-green and have a thin, rigid structure. Towards the base, they become woody, providing stability and strength to the plant.

Opposite narrow leaves emerge from the expanded nodes along the stems. 

The flowering stems are long and wiry and can be branched, bearing one to two pink flowers at the tips of the branches.

Dianthus lusitanus leaf (Rock Carnation, Portuguese Pink)

Leaf

The leaves are slightly fleshy and have a greyish-green to bluish-green colour growing opposite along the stem.

They are linear and entire (sometimes serrated at the base) without apparent veins.

The leaf length is, on average, 10 to 30 mm  (0.4 to 1.2 in) long and 0.5 to 1 mm wide.

Dianthus lusitanus flower (Rock Carnation, Portuguese Pink)

Flower

The flowers are usually pink and grow solitary or in pairs at the end of the branches.

Each flower is around 2 cm (0.7 in) in diameter and has 5 petals that are sharply toothed

The flower is held inside a long calyx (19 to 23 mm) that is progressively tightened on the upper end.

At the base of the calyx are 4 to 6 bracts with a lanceolate pointy shape, about ⅓ of the size of the calyx.

The flowers start blooming at the end of spring and continue until mid-summer.

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Dianthus lusitanus Habitat

Rock Carnation or Portuguese Pink, is native to the Mediterranean basin, specifically  Portugal and parts of Spain. It thrives in rocky or stony areas, hence the common name “Rock Carnation.” It is commonly seen growing in the crevices of rocks.

It can be found at altitudes up to 2000 m (6500 ft)

Dianthus lusitanus Usage

Ornamental

Rock Carnation is primarily grown as an ornamental plant due to its attractive pink flowers, compact growth habit, and evergreen foliage.

It can be used in the following ways:

  1. Borders and beds: It is well-suited for border plantings and bedding schemes. Its compact growth habit, attractive pink flowers, and evergreen foliage make it an excellent choice for creating borders that provide colour and visual interest.
  2. Rock Gardens: As its name suggests, Rock Carnation is particularly well-suited for rock gardens. Its ability to thrive in rocky and stony areas, along with its low-growing form, makes it a natural fit for adding beauty to rock gardens or other alpine-style planting areas.
  3. In containers: It can easily be grown in containers, making it a versatile choice for patio gardens, balconies, or other limited-space areas. Its low-maintenance nature and attractive flowers make it an appealing addition to container arrangements.
  4. Cut Flowers: The pretty pink flowers of Dianthus lusitanus can be cut and used as fresh flowers in floral arrangements. 
  5. Wildlife gardens: The flowers of Dianthus lusitanus attract pollinators such as bees and butterflies. By planting Dianthus lusitanus in your garden, you can help support local pollinator populations and create more pollinator-friendly habitats.

Biodiversity

The flowers of Dianthus lusitanus, like other Dianthus plants, are known to attract pollinators such as bees and butterflies.  This plant is a valuable addition to the biodiversity of your garden and is ideal for wildlife gardens.

Erosion control

Due to its ability to thrive in rocky and challenging conditions, Dianthus lusitanus is sometimes used for erosion control on slopes, banks, and other areas prone to soil erosion. Its dense mat of foliage helps stabilize the soil and prevent erosion.

How to care for Dianthus lusitanus

Cold exposure

This plant is frost-hardy and tolerates temperatures down to -15ºC (5ºF) or less as long as the soil is well drained. Cold and humid soil can be fatal to it.

Add a thick layer of mulch to shelter the roots from low temperatures. It is best to use gravel. Due to its cushion habit that hugs the ground, organic mulches may retain too much moisture and may cause the stems to rot.

Sun exposure

Dianthus lusitanus prefers full sun. It thrives in bright, direct sunlight and can tolerate intense heat. Providing it with at least 6 hours of direct sunlight per day is ideal for its growth and overall health.

In areas with extremely hot climates or intense sunlight, some protection from the afternoon sun may be beneficial to prevent leaf scorch. Partial shade during the hottest hours of the day can help protect the plant from excessive heat and intense sunlight.

Soil

It prefers well-drained stony, or sandy soils. It dislikes soggy soil, which makes it more exposed to fungal diseases that cause root rot. So avoid planting it in places where moisture is stagnant.

It prefers acidic to neutral soils.

Watering

Rock Carnation is drought tolerant and can go for an extended period without water once it is established (about 5 months of drought if the temperature is not too hot). 

Once established, it should not be watered during the summer to avoid creating hot and humid conditions that could potentially foster fungal infections. However, in cases of prolonged drought or exceptionally high temperatures, you should water it. Remember to allow the soil to thoroughly dry out between watering sessions.

In the first year after planting, it’s important to water the young Dianthus every two to three weeks during the summer. This is because the plant is still growing its roots and needs extra water until it can reach deeper into the soil to get water on its own. This helps the plant stay healthy and hydrated as it gets established.

When watering it, you need to do it abundantly, giving the soil a generous soak so the water can penetrate deeply into the soil to allow its roots to grow deeply. Deep roots will allow the plant to survive longer periods of drought because the lower layers of the soil keep moist for more time.
To preserve the soil´s moisture, you should add mulch around the root area of the plant. Gravel is the best option for mulching.

Pruning

Pruning Dianthus lusitanus helps maintain its shape, encourage new growth, and promote better flowering. 

  • Give it a cleaning prune in early spring. You should cut back the stems that are old, weak or overly crowded. This will allow for better air circulation and light penetration which will promote a healthy growth
  • Give it a hard prune (always cutting above a healthy set of leaves)  immediately after the flowering period typically mid to late summer to help maintain its shape and encourage new growth.
  • Give it a light prune (deadheading) during the flowering season to promote continuous blooming-

When to plant Dianthus lusitanus

The best season to plant is typically in the spring or autumn, depending on your climate. It’s advisable to avoid planting during periods of extreme temperatures.

If you live in a location with moderate weather, you should preferably plant in the autumn season. By doing so, the plant gets a chance to develop its roots during the cooler months before the arrival of summer’s hot temperatures. However, if you encounter severe winters, it’s better to wait until spring when the danger of frost has passed, and the soil has warmed up, creating a more favourable environment for the plant to thrive.

How to propagate Dianthus lusitanus

The best way to propagate Rock carnation is from seed or stem cuttings 

Stem cuttings: take softwood cuttings in spring or semi-hardwood cuttings, in late summer or early autumn.

  1. Cut the stem just below a leaf node
  2. Remove the lower leaves, leaving a few pairs of upper leaves intact. 
  3. Plant in a well-draining medium. Keep the medium consistently moist and provide indirect light. 
  4. Once the roots have developed, transplant the rooted cuttings into individual pots or desired garden locations.

Seeds: sow seeds in late winter or early spring.

  1. Sow the seeds in a well-draining medium. Lightly press the seeds into the surface of the soil without covering them. 
  2. Maintain consistent moisture and provide indirect light. 
  3. Germination typically takes 1-2 weeks. Once the seedlings have grown a few sets of true leaves, transplant them into individual containers or garden beds.

A good online source for plant propagation techniques can be found in RHS propagation article.

If you prefer books, I can recommend the following:

  • Creative propagation: a grower’s guide by Thompson, Peter,
  • RHS Propagating Plants: How to Create New Plants For Free by Alan Toogood, Royal Horticultural Society

Sources

Sources of information used for this article

Internet

Article from University of Evora

Article from Kew

Vol VIII from FloraIberica

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