Dahlias – the Barbara Windsor’s of the Flower World!
When I started my horticultural career as a jobbing gardener at Haringey Council in North London, much of the work was mundane and pretty unrewarding. However every day during the late summer and until the first frosts, my heart was lifted by the technicolor blooms of an astonishing collection of dahlia plants. Their serried military ranks filled one corner of the large nursery that was the base for our day's work and every day I made a detour to receive their joyous benediction before facing the harsher realities of removing rubbish from shrubberies along the Great Cambridge Road. I never did understand what, if any, their function was within the Parks Department, but I suspect it may well have been the Nursery Superintendent indulging his particular passion, this was a more easy going era before the chill wind of competitive tendering swept away any such indulgences!
Since that time I have always had a soft spot for their cheerful, "Carry on up the Border", brassy and flamboyant charms. For many years deeply unfashionable and frowned upon by the more sensitive Bloomsbury-like fashionistas of the gardening world they are now enjoying a revival and once more grace the gardens of those in the know. In my opinion, rightly so because nothing else has the floral firepower nor flaunts such brilliant, clear colours to brighten the season when so much else is descending into autumnal subfusc tones. The razzamatazz of their blooms is fortunate because frankly their foliage is not a selling point. Coarse, like the pinnate and potato, the only exception being the purple and dissected leaves of that most acceptable of dahlias, the semi-single and deep red "Bishop of Llandaff".
Dahlias can be used in the border and are strengthened and work best when combined with plants whose main feature is their foliage such as grasses, ricinus communis, the castor oil plant or cannas, but the traditional way has been as I first experienced them in my youth, grown as specimen plants in their own border. As a consequence that's how we grow them at West Dean Gardens, a whole bed of them in our cut flower area, because they make the most vibrant cut flower to light up the dullest room.
They are simple to grow requiring only a reasonable soil, generous feeding and lots of sunlight, they are definitely not a shade plant, some pretty heavy duty staking and tying before they start to produce flowers and most importantly rigorous and clinical deadheading every three to four days, without this they will soon look messy and stop flowering if allowed to produce seed. Generally, they are pest and disease free but can be susceptible to aphid infestation, easily controlled or more seriously virus attack which can't be controlled and sadly, affected plants should be destroyed. Some people suggest lifting plants each late autumn is unnecessary but we still lift ours after the first frosts have turned their tops to mush, wash the soil off the tubers, dry them upside down and then store them in a frost free shed covered in spent compost to stop them shrivelling too much. They are then brought out again at the end of April, soaked in water if they are dehydrated and then planted with the tops of their tubers four to six inches below ground and so the cycle begins again.