Mandy Bradshaw looks at the different varieties and explains why there is a dazzling bloom for everyone
It’s often said that if you don’t like dahlias, it’s just because you haven’t found the right one. So extensive is the range of available shapes, colours and sizes of this summer star, there really is bound to be a choice that works for you.
‘Thomas A. Edison’ is a sumptuous mass of dark purple, while ‘Wizard of Oz’ is a tightly packed dainty ball of pink and white. Single-flowered varieties such as the yellow ‘Bishop of York’ are fantastic for pollinators, the long-stemmed ‘Karma’ range have been bred for cutting, and ‘Honka’ dahlias have flowers reminiscent of childhood beach windmills.
When it comes to size, the tree dahlia, Dahlia imperialis, can reach a towering 4m (13ft) while dwarf varieties including ‘Gallery Art Nouveau’ get to around 35cm (14in), making them perfect for the front of borders or containers.
“There’s definitely one for everyone,” says Louise Danks, who holds a National Collection of Dahlias, “whether it’s one of the big, bold, blousy blooms, looking like it’s escaped from the Rocky Horror Picture Show-types, or something a bit more sophisticated like Dahlia merckii, which is perfectly at home in a mixed herbaceous border. Then there’s everything in between.”
Dahlias are divided into 15 different classifications that include paeony, stellar, star, cactus, pompon, waterlily and collarette. Within that there is every colour except a true blue, from clear whites and pinks through to orange, yellow, dark purple and red.
“I think you would be hard pushed to leave my field without thinking ‘That one was okay. I would grow that in my garden’,” says Louise.
How to grow these beauties
Most gardeners either buy potted plants in summer, which can be planted on to bloom, or grow their dahlias from tubers, which should be potted up in early spring in peat-free multipurpose compost in a one-litre container. The key with tubers is to keep them moist but not waterlogged and protect from frost.
“When you get to about four pairs of leaves, pinch out the top so you get a bushy plant,” advises Louise, who grows 1,700 varieties and 22 species dahlias at Camborne, Cornwall.
When to plant out
Once the risk of frost has passed, dahlias can be hardened off and then planted in the garden – either into borders, or containers if you’re growing a smaller variety.
They come originally from Mexico and Central America so need a sunny spot in soil that retains moisture but doesn’t get waterlogged. Make sure the ground is well prepared as they are fast-growing, hungry plants. Add plenty of good organic matter
