Our Dianthus Growing Guide

Perfect for containers, the edges of borders and even in rockeries, Dianthus provide perfect ground cover while also producing an abundance of flowers during the spring and summer.

There are hundreds of species of Dianthus but most good garden centres stock either Carnations, Pinks or Sweet Williams, although very similar there are some subtle differences between the three.

The good news is all three Dianthus species are easy to grow and maintain – just follow our growing guide.

What’s the Best Type of Soil/Compost for Dianthus?

All Dianthus prefer fertile, well-draining soil/compost so will perform well in raised flowerbeds/borders, rockeries and elevated areas of the garden.

Dianthus can be grown in containers, but we recommend adding coconut coir and either perlite or vermiculite to aid drainage and moisture control. Containers should have drainage holes at the base and preferably you should raise them off the ground with feet.

Compacted waterlogged soil can lead to stem and root rot so try to aerate heavy clay soils with additives where possible.

The Best Location For Dianthus

In addition to locating Dianthus in well-draining fertile soil, do place them in a sunny position if possible.

While Dianthus will cope with a partially sunny spot, they prefer at least 6 hours of sunshine per day.

Avoid areas of the garden with little or no sunlight as you’ll see fewer flowers.

Dianthus are generally considered frost-resistant but as with many plants, may suffer during a particularly hard frost.

Spacings

Most Dianthus species have a spread of between 6″ (15cm) and 12″ (30cm).

A good starting point for borders and flowerbeds is to space Dianthus around 12″ or 30cm apart.

You should plant more compact species of Dianthus between 6″ and 8″(15cm/20cm) apart, which is also an ideal spacing for plants in containers.

How Often Should Dianthus be Watered?

Dianthus should never be allowed to sit in waterlogged soil as rot root is the number one cause of plant failure.

After planting out, water the plant regularly until established and growing well.

Assuming the Dianthus has been planted in well-draining soil or compost, water weekly during the summer when it’s hot. You can water more frequently provided the soil is very well-drained.

Avoid overhead watering to prevent crown rot, which is a common problem across all Dianthus species. Water from the side and avoid splashing the centre of the plant. This is especially important if the Dianthus has been planted in a shaded location where the excess water may not evaporate. Shaded areas are fertile ground for fungal diseases which spread by overhead watering and splashing.

Dianthus are well-known by gardeners for their both heat and drought tolerance, so they can easily cope with a typical British summer, there’s no need to water them every day, even on the hottest of days.

How Much Fertiliser Do Dianthus Plants Need?

Dianthus prefer a fertile growing medium, so for optimal growth and blooming, apply a general garden fertiliser at the time of planting and then every 4 weeks during the spring and summer.

For plants grown in small containers, fertilise lightly every fortnight.

Dianthus are hardy plants, so while regular fertilisation helps with growth, it’s not essential. As an alternative, you can bed in well-rotted manure once a year in the spring.

How to Prune and Deadhead Dianthus

Most Dianthus plants will bloom from spring to late summer, but you can extend this with regular deadheading.

Many species of Dianthus, such as Passion (a Pink) suffer from heavy flowers (often several on the end of each stem) which causes the stems to bend right down to the soil. Regular deadheading and tidying up the plant by pruning back long stems should help to keep the plant looking neat and compact and may also extend the flowering period into the Autumn.

You can prune Dianthus anytime from mid-spring to Autumn if it needs a general tidying up. Aggressive pruning, down to a neat mound, can be done at the end of autumn.

The image above shows Dianthus “Passion” (a Pink) with large heavy red blooms on narrow stems.

Common Diseases and Pests

Dianthus plants are very resilient, and most garden pests tend to ignore them; however, problems usually arise when the plant is overwatered or located in a shaded location.

Stem, root and crown rot are the most common reasons for Dianthus to fail, but in general, Dianthus is easy to maintain and still a great choice for beginners or those with limited time for their gardens.

There are few pests to worry about, and most of them can be treated with commercial pesticides. Alan Titchmarsh once described Dianthus as “tough as old boots“, and we think his comment is spot on.

The team here at DIY Gardening hasn’t experienced any problems with pesky slugs or snails, but we have heard reports of spider mite, aphids and Carnation Fly maggots causing issues to other gardeners.

How Long do Dianthus Plants Live? 

Dianthus can be annual, which means they only live for one year, biennial, which means they live for two years or perennial; i.e. they live for several years.

The most popular Dianthus plants are perennials, and we’ve found they last between 3-5 years before they need to be replaced or split.

To keep your Dianthus collection looking healthy and producing plenty of colourful blooms, we suggest regular splitting and propagating.

Propagating and Splitting 

Every Dianthus species can be grown via propagation.

Start by pulling away or cutting off a non-flowering shoot, cut the stem to just below a leaf node and trim off the lower leaves, leaving only four top leaves. Then propagate as you would most plants; dip in hormone powder or gel and insert into a well-drained potting mix, water and kept sealed to increase humidity.

Once the roots have struck and appear at the bottom of the pot, it’s time to move them to larger containers.

Dianthus can also be split, and we recommend doing this every 3-5 years or when you notice dead spots at the centre of the plant.

Dianthus Companion Plants

Dianthus is a versatile plant often found towards the front of a border or flowerbed as they sit beautifully in front of taller companion plants such as roses, lavender and ornamental grasses.

Place them alongside popular annuals such as pansies, petunias and geraniums or if grown in a rock garden, choose alpine plants such as creeping phlox or stonecrops.

8 Recommended Dianthus Companion Plants

Try these companion plants, they go well with Dianthus:

Snapdragon:

Like Dianthus, Snapdragons require well-drained soil and a sunny or partially sunny spot in the garden.

Red Valerian:

Red Valerian grows up to 1 metre tall and sits perfectly behind a row or two of low-growing Dianthus plants. Img by Gittinsj | Img licence

Photos of Dianthus From Our Garden

We took these photos in 2020, the red Dianthus is a Pink called “Passion” while the white and red is another Pink called “Coconut Sundae”.

All of these plants were grown via propagation and are less than one year old. We expect them to fill out and cover the ground well by next summer:

More Photos

We’ve published more photos of Dianthus here, you are free to share them.

DIY Gardening’s Top Ten Dianthus Growing Tips

Here are our top ten quick tips for growing Dianthus:

Recommended Products

Below is a selection of products we recommend if you’re planning to grow Dianthus:

Inspiration and Ideas

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