Dianthus

Photographs by Sabina Rüber

Meaning ‘divine flower’, Dianthus is a group that includes old-fashioned carnations (D. caryophyllus) and pinks (D. plumarius) as well as Sweet Williams (D. barbatus). There are many hundreds, if not thousands of varieties of carnation and pink, and although both are easy to grow from seed, it is probably easier to buy them as plants as they are widely and cheaply available from nurseries and garden centres. Growing Sweet Williams, however, is more satisfying as they are useful for both borders and containers, and the range available from seed is superior to those found in garden centres. The other group worth growing from seed – and just as easy – are some of the species themselves, such as D. carthusianorum and D. superbus which have grown in popularity in the last few years.

Sweet Williams are short-lived perennials often grown like a biennial, to be sown in late spring or early summer and flowering the following year. Known for their sweet, spicy scent, they grow to around 40-60cm tall, forming domed clusters of cheerful little flowers in dolly-mixture colours. They are incredibly easy to grow; tough, hardy little creatures. There are dozens of cultivars, but ‘Auricula Eyed Mix’ is one of my favourites, with sparkling flowers in shades of cerise, pale pink and scarlet, each fringed with white and with a central white eye. ‘Sooty’ is another interesting and unusual variety, with the deepest purple blooms, as near to black as flowers can be, as well as red stems and dark leaves.

Of the dianthus species, D. carthusianorum was spotted at the Chelsea Flower Show a few years ago, and has been fashionable ever since. A perennial plant that flowers the same year if you sow it in early spring, it is incredibly easy to grow from seed, and perfect for a gravel garden. I have it all over my front garden in full sun, where it bobs around with Stipa tenuissima, pale yellow Digitalis grandiflora and loose-limbed Euphorbia oblongata. Growing 50-75cm tall, in June and July it produces sprays of small, intensely coloured magenta flowers in little clusters of six or seven that float above tussocks of grassy leaves on strong stems. D. cruentus is similar, with blood-red flowers (but more difficult to get hold of in seed form), starring in one of Cleve West’s Chelsea gardens (2011).

Sweet Williams won’t flower until the following year, so should be treated like biennials and sown in late spring or early summer. They can either be sown direct in the garden or under cover, but either way they need a period of cold to initiate the flower buds, so if you are initially sowing them in modules, germinate them in a cold frame rather than giving them too much heat, and then plant out in the garden in autumn so they have the winter outside. Perennial species such as D. carthusianorum and D. superbus will flower the same year if you sow them in late winter or early spring under cover. The seeds are big enough to plant in individual modules, sown on the surface of the compost or covering lightly with vermiculite, as they need light to germinate. Keep them warm initially at 18-21C, and then cooler as soon as they have germinated, planting them out in the garden as soon as any danger of frost has passed. All dianthus hate being wet, so ensure that they are planted in a free-draining area of the garden and don’t over-water.

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