Dianthus are making a welcome comeback, says Gillian Vine.
The release this year of a sweet-smelling dianthus called Memories sums up the twin attractions of these flowers: most of us recall them from childhood and almost everyone loves the clove-like perfume.
Although there are about 300 dianthus species, from a gardener's viewpoint they can be loosely divided into four groups - Sweet William (D. barbatus); those usually treated as annuals (D. chinensis); carnations and clove pinks (D. caryophyllus); and perpetual pinks (D. x allwoodii and mat-forming D. gratianopolitanus).
Mainly from Europe, although some come from Asia, gillyflowers (D. caryophyllus) were well-established in England by the 15th century and became known as clove pinks after it was found the flowers could be used by the less affluent to flavour wine, instead of prohibitively expensive cloves.
Generally, carnation cultivars have been developed from D. chinensis and D. caryophyllus, while the smaller border pinks are mainly hybrids from three other species.
The French developed several new strains, including the Chabauds and Malmaisons, and subsequent crosses resulted in better border carnations, as they were termed, as well as perpetual flowering varieties that built on the work of American breeder Peter Fisher.
Because they had tall stems (75cm-1m) that were strong enough to support flowers up to 6cm across, these varieties quickly found favour with florists and their descendants are still important cut flowers.
Today, India, China, Sri Lanka, Turkey and Colombia grow vast quantities of carnations for export.
They fell from favour, possibly because the carnations developed for the cut-flower industry looked good but tended to have little or no perfume.
Some, like the tree carnations that will grow 2m or more, have almost vanished, but smaller dianthus (''pinks'') are making a comeback, in part due to the efforts of breeders such as Dr Keith Hammett, of Auckland, whose Scent from Heaven series has the sweet perfume of the old gillyflowers.
Pink, white and plummy reds are the main colours in the clove pinks, while carnations also come in yellow and apricot tones, as well as the grey-mauve of the old variety Maori Chief.
Except for Emile Pare, a ''mule'' that can be grown only from cuttings or by layering, all dianthus can be grown from seed sown in late summer and autumn.
They can also be propagated from cuttings or by dividing large plants. Less commonly, layering is used.
This involves pinning stems to the ground to encourage them to root, after which the rooted pieces are cut from the main plant.
Dianthus grow best in a sunny spot in well-limed and manured soil with the best possible drainage to prevent root rot.
For larger, better-shaped flowers on carnations, nip out all side buds and leave just the main one at the top.
Colour coded
- Carnations are subdivided according to colour.
- Self-colours have no other colours on the petals, while flakes have a clear background, ''flaked'' with one colour. Those with more than one colour are known as bizarres, while picotees are white or yellow with a narrow band of colour (usually red) on the margin of each petal.
- ''Fancies'' are multicoloured blooms outside the standard for picotees and bizarres.
