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Brilliantly coloured Sweet William

Perhaps the best known of the Dianthus clan is Sweet William which bears its brilliantly coloured blooms in large clusters at the top of stout stems.

Perhaps the best known of the Dianthus clan is Sweet William which bears its brilliantly coloured blooms in large clusters at the top of stout stems.

Sweet William is a traditional cottage plant famous for its late spring and early summer colour and sweet clove-like perfume. Dense clusters of flowers are produced on sturdy self supporting well branched stems in a superb mix of complimentary colours.

Sweet William (Dianthus barbatus) is a biennial that belongs to the Dianthus family, which also includes Carnations and Pinks. There are over 300 species of Dianthus, and hundreds more of hybrid varieties. The group includes annuals, biennials and perennials.

Dianthuses belong to the Family Caryophyllaceae and the Order Caryophyllales, which makes them botanically related not only to the cottage garden stalwarts baby’s-breath, thrift and Maltese cross, but more distantly to amaranth.

Dianthus was named by Greek botanist, Theophrastus. He named them Dianthus from the Greek dios, ‘divine’ and anthos, ‘flower’. However, some writers have credited the naming to Carolus Linnaeus, the great 18th century Swedish botanist.

Sweet William features low mounds of grass-like foliage with cheery pink, red, purple, white or violet flowers which are often bicoloured.  There are both single and double forms of Sweet William and seeds can be obtained that will produce plant heights ranging from 10cm to 60cm tall.

Various seed companies feature their own varieties, with very low growing kinds in both singles and doubles that are especially suited to rock gardens and the edges of narrow perennial borders. The tall varieties belong in the middle ground of the flower border. It is also a wonderful plant containers, mass plantings and meadows.  It makes a long-lasting, fragrant cut flower, and is an excellent choice for dried flower arrangements.  It has a mild, sweet, clove-like scent when brushed.  The flowers are edible and also have a clove-like taste.

The soil conditions should be slightly alkaline, fairly rich, quite loose and well draining. Poor drainage or over-watering will kill the plants. Mix in a general garden fertiliser before planting out.  It prefers full sun in all but the hottest areas, where it should be given part shade. It does best in cooler weather, but given the right conditions it will survive a hot summer.  It appreciates a feeding every 6-8 weeks with a balanced fertiliser, and deadheading to prolong bloom.

For planting in a bed or border: Use a trowel to dig an individual hole for each plant, deep enough to submerge the root ball and keep the base of the stem at soil level. Position your plant and fill the hole back in. Gently firm down and water in. Leave a 15 cm space between plants, and bear in mind that the plants will grow to a height of between 20 and 40 cm.

Weed around the plants as weeds will compete with the Sweet Williams for nutrients and water. Apply a layer of mulch once the plants are established. Inspect the plants for any signs of aphids, nematodes or slugs, and remove or apply appropriate deterrents as necessary.

The nectar of Sweet William will attract bees, butterflies and birds to your flower beds – it’s a good choice for a wildlife orientated garden.