MONTY DON

Sweet williams have been the surprise of the season, says our gardening expert – plant them now for next year

One of the stars of my garden this year has taken me by surprise. Last year I sowed trays of sweet williams and planted the seedlings as much as border fillers as any kind of centrepiece. But they have stolen the show with a range of colours from the palest pink to a red so deep that it is almost black.

Sweet williams are easy to grow and hardy, although usually they do best in alkaline soil that is light and well-drained, and they do not thrive in warm, humid summers. My soil is neutral and heavy, and although not particularly warm, this summer has been humid to the point of soggy. Yet thrive the sweet williams most certainly have.

They are normally grown as a biennial, which means if you sow the seed now you’ll have a magnificent display starting next year in April or May and staying in flower to the end of July, although they are actually short-lived perennials and if you cut them back hard after flowering they will return the following year with just as good a show. Sometimes you see an old cottage garden with sweet williams that are years old, still flowering on a woody plant, albeit in a modest, limited way compared to those renewed every few years. The answer is to sow fresh seed every spring or summer and replace older plants as they become less and less productive. The seed germinates in quite low temperatures so does not need a greenhouse, let alone a heated mat. An outdoor seed bed protected by a cloche or a cold frame is ideal. Once they are large enough to handle the seedlings should be planted in rows to develop into sturdy plants over the summer months and then moved into their final position in the border in autumn.

They will complete their display by the end of July so need to be planted among something that will produce more blooms in late summer and autumn. I use dahlias and cosmos to accompany them and carry their flowering baton forward.

Sweet williams ( Dianthus barbatus) are related to pinks and carnations and come originally from the Pyrenees and Balkan moun- tains. However, since their introduction into northern Europe in the 16th century they have become one of the archetypal British cottage garden plants with their rather broad leaves and the flowers held upright on stiff stems, unlike many pinks that tend to flop.

The Latin name can roughly be translated as ‘bearded pinks’ and refers to the markings around the entrance to the pollen that the plant has to entice butterflies and moths to pollinate. So as well as being fragrant and vibrantly beau- tiful they are also an excellent flower to grow to encourage butterfly activity in your garden.

Although I love the carefree mix of all the shades of pink in my cottage garden, for the Jewel Garden – where we carefully select plants for the richness and intensity of their flowering – I am more selective, looking for the darkest reds possible. The darkest red of the sweet williams has to be ‘Sooty’, with leaves such a deep red they appear almost black and large flowers that are the darkest maroon. ‘Dunnett’s Dark Crimson’ is another variety that has especially velvet-rich flowers although with green foliage. Dianthus barbatus has been crossed with Dianthus plumarious to make a pink that is exceptionally long flowering – but sterile. However they, like all pinks, can be propagated from cuttings taken now from shoots that do not bear a f lower.

Dianthus plumarious will grow and flower in the crevices of old walls or paving and has glaucous foliage and the most fabulous fragrance. I have not grown it but just writing this certainly makes me want to for next year.

If you’d like more advice from Monty Don, visit www. mymailgarden.co.uk/monty.

Monty with his sweet williams