Dianthus Pinks | Ultimate Australian Growing Guide

What is a Dianthus?

Dianthus, also known as pinks, and carnations, are Mediterranean plants, native to Greece, Croatia, Albania, Italy, Sicily and Spain. Quite how their native spread is so wide is unknown, but they are easy self-seeders and were most likely spread around Europe by migrating birds.

Carnations thrive in well-drained soil, and while they benefit from feeding once a month during the growing season, are really quite happy in poor soil, and even heavy grit mixes, as long as there is some moisture retentive compost somewhere in the mix.

Dianthus come in a massive range of sizes and some cultivars are up to 60cm tall at the height of the season, sending towering flower spikes up above other Mediterranean alpines that grow alongside them in the borders. 

Dianthus flowers have a distinct almost vanilla sweetness to them and have traditionally been used as lapel flowers for that exact reason (and Sean Connery did them a few favours in his many years as James Bond).

5 Best Dianthus Species to Grow in Australia

How to Grow Dianthus

Dianthus need good drainage and full sun. They are very susceptible to root rot and hate sitting in heavy clay soils, but you can easily improve the soil with horticultural grit as they don’t need any particular nutrients to thrive.

They are most often sold as perennial bedding plants but make excellent additions to rockeries and alpine beds.

In our garden, we have a few different cultivars, including Sweet William (the classic bedding dianthus), Dianthus plumarius (with its gorgeous purple hues), but it’s Dianthus carthusianorum that really takes the prize in our borders, reliably towering over the other edging plants at 60cm tall.

We’ll cover individual aspects of dianthus care and maintenance later, but as a very basic guide, they need well-drained soil, full sun, and a big drink every few weeks in dry spells. Once you know those basic rules, you know how to grow dianthus.

How to Propagate Dianthus Flowers

Dianthus are incredibly easy to propagate from seed, cuttings or division - although dianthus cuttings and dianthus division are basically the same processes.

For gardeners looking to understand alpine plants, and gain experience, dianthus are very representative of Mediterranean alpines in their habit despite not actually being alpines.

Because they grow in clumps from a single rootstock, they are easy to divide by basal cuttings, and as you’ll no doubt have seen if you already grow dianthus, they have incredibly generous seed heads, packed with potential new plants.

Propagating Dianthus from Seed

How to Propagate Dianthus Outdoors

To propagate dianthus outdoors, simply prepare the ground by mixing grit or sand into any clay soil, or raking over well-drained soil for an even texture.

When the ground is prepared, sow thinly where you want them to flower, and water them in. With any luck, you’ll have plenty of new carnations next year.

Propagating dianthus outdoors in spring will give wonderful silvery foliage in the first year but flower the following year, so it's best to propagate outdoors in late summer so they have a chance to establish and flower early the following year.

How to Propagate Dianthus Indoors

Dianthus grow easily from seed, with a good germination rate, and can be sown either directly into the garden in appropriately well-drained soil, or a mix of seed compost and vermiculite on the kitchen windowsill.

Dianthus take around 7-14 days for germination and should be planted indoors 7-8 weeks before the last frost. If there is a risk of frost in your part of Australia, make sure to propagate them 8 weeks before the last frost, indoors, at the very latest, which will give you some chance of flower the same year.

How to Take Dianthus Cuttings

Cuttings are commonly known as pipings, and they’re not strictly cuttings. Because they are clump-forming perennials they spread slowly from the centre of the plant.

This means you can simply take a firm hold of a non-flowering stem at the base, and pull gently but firmly upwards. 

Dianthus stem should come out with small roots attached, and they will quickly root either directly in the garden or in a pot filled with a standard cutting compost, Keep them well watered and in 3-4 weeks you should see small roots poking out of the bottom of the pot.

Caring for Dianthus

Caring for mature dianthus plants is really quite easy, mostly because they’re already much stronger than their young counterparts, but also because they need little water, no mulch and while they benefit from dead-heading, they don’t require it, so as long as you've got your soil mix right in the first place you can’t go far wrong.

Best Soil Conditions for Dianthus flower

Dianthus need well-drained soil and are happiest in neutral, or slightly alkaline conditions. While soil can be confusing, most gardens have a pH of 7 (neutral) to 8 (slightly alkaline) but its cheap to buy a soil pH meter if you’re at all worried about the average pH in your garden (they can be really useful on new build properties where the gardens are a mix of topsoil & rubble).

See our article on soil moisture meters for some useful multi-tasking ph testers. You can buy great alpine composts that will work perfectly for pots of solely dianthus or use horticultural grit to add to planting holes in the ground to help with drainage. 

In particularly heavy clay soils, mi horticultural sand and/or grit through the planting hole to improve conditions for dianthus.

Does Dianthus Need Mulching?

Dianthus should never be mulched, even if they're planted in a general border that gets routinely mulched, make sure to avoid any overwintering dianthus foliage, as the raised humidity around the lower parts of the plants will kill them off completely.

Dianthus hate being wet so any added moisture, while they are dormant, is unnecessary.

Dianthus Fertiliser

Dianthus don’t need fertilising. They're always happy in basic soils and will continue to thrive as long as they don’t stay completely dry for too long.

If you're worried that they're underfed, using a basic garden pour-and-feed fertiliser won’t hurt, but the best option is slow-release fertiliser granules which give the soil a general boost without adding moisture to the mix.

How to Water Dianthus

Dianthus are drought-tolerant plants, but do benefit from water in dry spells or particularly warm summers. There is no point giving them a routine watering every week as this is much more likely to kill them than feed them, so avoid watering dianthus unless the soil is visibly dry.

Dead-heading Dianthus

Dianthus don’t need pruning or cutting back. If there is a risk of frost, it can kill off a lot of top growth, but it will grow back in spring.

Throughout the flowering seasons though, it is important to keep dead-heading dianthus, as it prolongs their flowering seasons and prevents them from putting all their energy into seed production.

If your plants do go to seed though, make the most of it and try sowing them when the seed heads dry out. You’ll have dozens more plants for next year that way.

Repotting 

Dianthus spread very slowly so need repotting very rarely. If you need to move them, simply dig the entire plant out with a trowel and place it in a new pot filled with well-drained compost, improved with grit.

If the plant is outgrowing its container, one simple option is to tip the entire plant out of the pot (root-ball and all) and split it right down the middle.

It’s that simple, that’s two plants from one. Really mature dianthus can be split into four new plants if you’re brave.

Light Requirements

Dianthus need full sun, and won’t tolerate shade at all. If you have a South facing garden, consider where the sun falls in the afternoon.

Any spot with more than 6 hours of direct sunlight will be perfect for dianthus plants but the more sunshine you can give dianthus plants, the better.

Common Dianthus Pests and Diseases

Aphids and spider mites are the only common dianthus pests. They don’t attract slugs and snails, and there are no animals that have developed a taste for them so they are really quite safe in the garden.

If you ever notice aphids or spider mites on dianthus, just blast them off with a hose in dry weather or plant flowers that attract ladybirds in the surrounding area.

The only diseases that will actually kill dianthus are caused by over-watering and high humidity, so in most parts of Australia, leaving to their own business and letting nature take care of them is enough care.

However, if you do notice brown patches or spots on the leaves these can be the signs of serious problems that need to be dealt with before they take over the plant. Here’s our guide to dealing with the most common dianthus diseases:

Bacterial Leaf Spot on Dianthus

There are a few different causes of bacterial leaf spot, and dianthus leaf spot, but the most common is wet foliage. Tiny scratches and scraps to leaf surfaces aren’t visible to the naked eye but are enough to let bacteria in, so when you water leaves and raise the humidity, bacteria spread by insects takes hold and causes even brown spots across the leaves. 

To prevent leaf spots from spreading to other parts of the plant, keep the leaves dry and water only from the base, and remove any spotted leaves so they don’t have the opportunity to spread to other healthy growth.

Dianthus Fusarium Wilt / Stem Rot

Fusarium wilt will lead to all the new growth in spring and summer turning yellow and dropping to the floor. Also called dianthus stem rot, this fungal disease spreads through airborne spores, and grasps onto damp plant material or settles into damp soil. 

You’ll quickly begin to see that patches of the plant turn yellow together and the stems become misshapen. There is no way to cure fusarium wilt once it has set in, but you can remove the affected parts of the plant and change the soil to prevent it from spreading.

Using organic fungicides and slightly raising the soil pH can help kill the fungal spores too.

The same symptoms are present in other causes of stem rot, including Rhizoctonia fungus which, again, needs to be cut out of the plant and disposed of, before cleaning the rest of the plant to prevent cross-contamination.

Common Problems & Tips for Planting Pinks

Aside from problems caused by pests and diseases, dianthus can suffer if they are left in damp conditions. If you ever notice yellowing leaves without any other signs of rot (like wonky stems, or black patches), the best solution is to dig them up and move them somewhere brighter.

If you love your dianthus in their current position though and want to help drainage rather than increase light and heat then try digging them up, pouring a layer of horticultural grit into the base of the planting hole, and then pop your plant back into the hole.

Within a few weeks, it should start to respond positively to the improved drainage.

Frequently Asked Questions About Dianthus 

Does dianthus grow back every year?

Dianthus are perennial plants that grow back every year. They are sold as tight clump-forming plants and for the first few years they will work well in formal gardens, but after about four years they will start to look leggy.

You can either cut them back to the ground to sprout or move them to a more naturalised part of the garden.

Does dianthus grow well in pots?

Dianthus are perfect for pots and containers and are much easier to grow for most gardeners when you have control of the soil mixture for container planted dianthus.

They love good drainage, and full sun, so by planting pinks in containers you can perfectly control their soil, light and moisture.

Do dianthus spread?

Dianthus spread very slowly, but will eventually form a carpet of evenly coloured flowers on top of delicate silvery foliage. Because they’re slow to spread, you can easily control them and keep them neatly restricted to just one part of the garden though, and they certainly won’t become uncontrollable.

Will dianthus bloom all summer?

Dianthus are one of the most reliable flowering plants in the garden, blooming all spring, all summer and even into the early autumn once they have fully established.

To get the most out of their flowers, you need to dead-head spent flowers as soon as they start to fade. This lets new flowers shoot up and take their place.