Your year of dahlias
Carol shows how to give your borders the wow factor with dahlias
Dahlias are from Mexico and Central America – isn’t it obvious? Obvious is the right word for them as dahlias don’t know how to be subtle. Their big, blatant flowers strike up a carnival of colour that nobody can turn a blind eye to. Nothing is more vivacious. Their vivid f lowers bring the sound of a mariachi band right into the flowerbed and will fill the whole garden with energy. At one time, ‘refined’ gardeners would never have dreamt of growing dahlias. Too often they were the persona non grata of the f lower border, confined to the allotments and vegetable patches of enthusiasts, many of whom grew them exclusively for show. In modern times, thanks to such prestigious champions as Christopher Lloyd at Great Dixter, dahlias have found their place in garden society, but although they have been grudgingly accepted, they will never be regarded as respectable. Thank goodness. Those of us who love them, exult in them. Whichever dahlias you grow, have fun with them – it’s obligatory! Take a bright red like Dahlia ‘Alva’s Doris’. Put it in front of a canna with bright, lime-green leaves and the two zing together so beautifully, you hardly need anything for a show-stopping display. If you want a truly psychedelic surprise, incorporate a few magenta or purple blooms. Dahlia ‘Hillcrest Royal’ is not only arresting, with its spiky purple flowers, but its stature – around 1m – gives you no opportunity to ignore it.
Dynamic combinations
The most popular dahlia of all, ‘Bishop of Llandaff’, is the most blatant – its red is that of fresh blood! Opening in succession from late summer onwards, scores of flowers are set off by the strong, bronze foliage that embellishes its sturdy growth. To show this dahlia off at its most dramat ic, team it wit h subt le companions – molinia or miscanthus, Cotinus ‘Grace’, silvery artemisia or the grey leaves of Elaeagnus ‘Quicksilver’. If you’re up for it though, why not let it do battle. Confronting the tall lime-green heads of Euphorbia palustris or E. schillingii, it is at its ostentatious best: the red is more blatantly red, the green more vividly acidic. Mix in a few heads of Crocosmia ‘Lucifer’, light the blue touch paper and retire. ‘The Bishop’, and other members of the clergy, may have been accepted into pol ite society, but there are
hundreds, nay thousands, of other dahlias which deserve a chance to enter the mainstream. Of those with bronze foliage, ‘David Howard’ is one of the best. It produces double, soft orange flowers in profusion and, although not as ostentatious as some, is always arresting. It needs little attention, standing up for itself without the help of stakes or supports. Most of the singles and many of the more compact doubles can stand up without help, but some of the larger cactus blooms may need a stout bamboo cane per flower to hold their heads high. The single-flowered forms cope best with rain, whi le the heads of some doubles can become sodden or dishevelled in wet weather. The single ‘Moonfire’ is a favourite of mine for the really startling hues of its blooms. It has a yellow background colour and rings of orange and red around its central disc. It is lovely with some of the hot-toned achillea and with grasses such as Anemanthele lessoniana in olive and orange, throwing up its tall airy flowerheads, while the foliage creates ribbons of underlying colour. We grew it, and other singles grown from seed, in huge containers last year alongside orange Agastache aurantiaca and a single African marigold, Tagetes linnaeus.
Seed, tuber or ready-grown?
Of the three main ways of introducing new dahlias into your garden, the cheapest is to sow seeds. And there have been exciting developments in recent years in dahlia seed combos offered for sale. One of the best is ‘Bishop’s Children’ bred from ‘Bishop of Llandaff’. All the seedlings from this mix share the same dark foliage and the range of their flower colour runs from scintillating magenta and rich crimson through orange and red, to yellow and pink. Most are singleflowered – a huge benefit to bees and other pollinators, as the pollen and nectar is easily accessible. Once they have grown for a season, they can be lifted and their tubers stored like any other dahlia. Sow seeds from February to early April. Sprinkle them sparingly on the surface of half trays of seed compost, cover with grit and press down lightly. Stand trays in shallow water until the grit darkens, then lift out, drain and place in a bright, warm place. You can also buy dahlias as dormant tubers or ready-growing potted plants. You can source dormant tubers from January until May, and the earlier you buy, the wider the choice of varieties that will still be available. Potted plants are usual ly available to buy from May. They are much more expensive since they’ve been grown
There’ve been exciting developments in recent years in dahlia seed combos offered for sale
on and nurtured, whereas if you buy tubers, it’s you who has to do all the nurturing. However, this is a pleasure and demands little effort, apart from potting up the tubers. Do this somewhere frostfree, in good rich compost, preferably loam-based if they’re to stay in their pots for any length of time.
Good soil and a touch of grit
I prefer to start dahlias in pots for three reasons: firstly, they can be planted out when risk of frost has passed; secondly, they make strong plants that can withstand inevitable slug nibbling when they go out; and lastly, they make robust shoots that are perfect for basal cuttings (see panel p31). When planting from pots, whether into the ground or into big containers, they should be planted to the same depth as they were in their original pots. Dahlias need good, fertile soil, moist rather than dry. If you decide to plant tubers straight into the ground, enrich the soil with compost and a balanced organic fertiliser if your soil is poor. Dig a hole deep and wide enough to accommodate the tubers with at least 5cm of soil above them. It’s a good idea to use plenty of grit in the planting mix and also to sprinkle a thick layer of grit on top of the soil to deter slugs. Water well during the growing season and occasional ly feed with a highpotash food such as tomato feed, to maintain flower quality and production. Stake where necessary and deadhead regularly to keep flowers coming. If you’ve got single dahlias you may want to keep a few seedheads to try producing your own plants from home-saved seed. If you do, it’s probably better to let a few of the first flowers ripen and go brown rather than wait until the end of the season and use the left-over flowers. And that’s all that’s required to ensure your garden sizzles with colour this summer. Turn over for a glorious gallery of dahlias catalogued by colour
If you buy tubers it’s you who has to do all the nurturing. However, this is a pleasure