Dahlias for Late Summer Colour


For many years dahlias seemed to be the preserve of dedicated breeders and growers who were committed to developing perfect exhibition flowers that were often so top heavy they had to be supported by unattractive stakes. Recently, though, we’ve rediscovered the delights of single-flowered dahlias and these plants have regained their rightful place in the easy-care garden.

The dahlia comes originally from Mexico and is named after Swedish botanist Andreas Dahl. It is the national flower of Mexico and was originally used by the Aztecs as a food plant. As the plants were spread around the world, their edible qualities were largely unappreciated but they became much loved for their beautiful flowers.

Renowned New Zealand plant breeder Dr Keith Hammett has been in the forefront of the dahlia revival. He has introduced many new self-supporting varieties that flower in gorgeous shades of pinks, reds oranges, bicolours and more. Many of these have contrasting – and very fashionable – dark maroon leaves. Others are very dwarf, which makes them suitable for the smallest pot garden. Dr Hammett’s Mystic dahlia range includes a stunning collection of dark-leafed cultivars topped with vividly coloured flowers.

Dahlia ‘Bishop of LLandaff’ is an established favourite with blackish-red foliage and brilliant scarlet flowers. It can reach up to more than a metre tall, so does best in a sheltered spot with plenty of sun. It was bred in Wales in the 1920s and given an Award of Merit by the UK Royal Horticultural Society in 1928.

Dahlia imperialis is the tree dahlia, a giant that grows to more than four metres so must, of necessity, have a protected position to ensure that the thick, brittle stems aren’t broken by strong winds. It blooms in autumn with bunches of lavender (and, occasionally, white) flowers that are great talking points. Because of its height and its tendency to break, this is a plant for the enthusiast, but if you want to impress friends and neighbours, it’s worth hunting for.

Dahlias are relatively easy to care for but, because they die back to their underground tubers in cold weather, their annual treatment is governed by climate. Tubers can be left in the ground through winter if the soil doesn’t freeze or stay wet for long periods (although experts recommend digging and dividing them every few years). In cooler areas the tubers should be dug up after the above-ground parts of the plant have died back in autumn. Clean tubers can be stored in boxes or bags filled with well-drained sand or coarse potting mix.

Watch out for powdery mildew on the leaves. A Yates Rose Gun can help with control of this fungal disease and will also take care of common insect pests. Water plants well in hot, dry weather. Drooping leaves will soon indicate when they need a drink.


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Annual Garden Calender