Dahlias are the dazzlers of the late summer garden, pumping out their wonderfully flamboyant flowers for weeks on end, right through until the first frosts.
No London garden or patio should be without Mexico’s exuberant national flower that is surprisingly easy to grow. The tough part is choosing from the fantastic diversity of shapes, sizes, colours and petal formations.
Take your pick — the strong cut stems last for weeks in a vase, while large, showy blooms look fabulous floating in a bowl — from single daisy flowers and small, neat pompom heads to huge, blowsy dinner plate dahlias and pointy-petal cactus varieties reminiscent of retro swimming caps.
The colour range is sensational. You could dress a border in sumptuous jewel tones, as in deep garnet cactus Chat Noir and hot-red, spiky-petalled Indian Summer, or choose a cooler palette of sorbet shades, such as vanilla peony-flowered Classic Swan Lake and palest apricot, powderpuff Café au Lait, which is a favourite of florists and big — literally — in brides’ bouquets.
You can buy ready-to-plant dahlias right now, and Bishop of Llandaff is probably top of the list, with good reason. Possessing a more exotic appearance than its name suggests, the Bishop has vibrant, velvety red daisy flowers with golden centres and the bonus of exotic chocolate-black ferny foliage that makes it a handsome plant even before the flowers appear.
Broad and bushy with a height of one metre, the Bishop looks the business in a large terracotta pot as well as in the border, where it mixes with other fiery flowers and foliage, such as scarlet crocosmia, dark red banana leaves and tropical cannas. The Bishop’s equally worthwhile offspring include the more compact, crimson-flowered Bishop of Auckland and David Howard, which has full, burnt orange flowers and bronze foliage. Both are perfect for pots.
My number one favourite for containers, though, has to be Roxy, a deliciously flirty little number with deep bronze foliage and stunning bright magenta round-petalled flowers that just don’t let up for weeks on end if deadheaded daily.
Considering they are such beauties, dahlias have an ugly start in life, in the form of tubers, an unpromising bundle of sticks that look like a dried-up bunch of small bananas. Early spring is the time to bury the tuber in damp compost, leaving the stick-like stem proud, and keeping it in a light, frost-free place. Then all you do is wait for the stick to sprout.
In early summer, the young, leafy plants can be potted up or planted out. The larger varieties will need staking. Once buds are forming, and right through flowering, treat them to a liquid tomato feed every week.
In late autumn, when the foliage has blackened, lift the tubers from their pots, clean them and leave to dry, then store them back in compost until the following spring. In London’s micro climate, dahlia tubers can stay in the ground, provided it is well-drained but, for insurance, give the tubers a deep, protective mulch.
If you buy dahlias now, you can treat them in the same way, so they will produce flowers for years to come. But for the best selection, buy or order dahlia tubers in February — www.sarahraven.com has one of the best catalogues, as well as colour co-ordinated collections.
Best policy of all is to see them in all their summer finery now and for weeks to come, at large gardens such as Great Dixter, West Dean, Arundel Castle and Chenies Manor, as well as at Kew and RHS gardens Hyde Hall and Wisley, where you can see the National Dahlia Society’s stunning displays at the Wisley Flower Show from September 8-13. Be warned — you will want to take plenty of pictures, and will have some tough choices ahead.