Dahlia

Photographs by Sabina Rüber

I never thought of growing dahlias from seed until quite recently, as I had always grown them from tubers. This is because the named hybrids we grow have been reproduced vegetatively (ie by cuttings) because they are so variable from seed. But actually, growing dahlias from seed is incredibly easy and they grow and flower satisfyingly quickly. Some seed companies sell mixed seed strains of bedding dahlias that tend to be gaudy and rather squat, growing to only about 50cm, but there seems to be a backlash against the more artificial-looking dahlias and a return to flowers nearer the original species – and in fact more and more of us are growing the species themselves. These single, delicate flowers bear no resemblance to the frilly confections that grace the show-benches or flower shops, and are much better at attracting the insects than the sterile hybrids.

One of the most attractive and easy dahlia seed strains is ‘Bishops Children’ (above) which produces single, daisy-like flowers in rich velvety shades of red, magenta and burnt orange. The seeds germinate readily and grow quickly to produce flowers within a matter of months, forming tubers that can then be lifted and replanted the following year. I have been experimenting with growing some of the species from seed, and so far all have been easy, including the crimson-orange D. coccinea and two pink-flowered species: D. australis and D. merckii. These species dahlias produce small, delicate flowers on wiry stems and are tall with an airy habit – they aren’t as showy as some of the others, but they are excellent border fillers for late summer, and will continue flowering until the first frosts. My final recommendation is for a seed mix called ‘Sunny Reggae’ (left) with a mixture of single and semi-double flowers in shades of rusty orange, apricot and pale peach, great for pots.

Dahlia seed is easy to germinate and should be treated in the same way as any other half hardy annual: in other words sown indoors in late winter or early spring, to be planted out in late spring or early summer. The seed is elongated like cosmos and zinnia, and can be sown in individual modules, germinating readily at temperatures of 18-20C. After germination, move the seedlings to an unheated greenhouse to grow on. If the module plugs get congested pot them on into 9cm pots, and eventually plant them out into a sunny, sheltered position into fertile, well-drained soil.

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