With a wide choice of flower shapes and colours, dahlias are unrivalled for giving a showy display from summer into autumn. You can combine them with other late-flowering plants like salvias and grasses to boost late-season borders, add dwarf cultivars for colour in summer containers or grow them in rows to give lots of cut flowers for your home.
Flowers can be open-centred and daisy-like or multi-petalled spheres or jagged ruffles, from 10cm (4in) up to 30cm (1ft) across. Their colours are diverse too – from sedate pastels through to riotous reds and oranges. The foliage is usually green, but a few have dark leaves for added drama. They can range in height from a compact 30cm (1ft) up to a stately 1.5m (5ft) or more.
Dahlias like a warm, sunny, sheltered spot with free-draining soil and regular feeding and watering to ensure the best flowering display. Tie stems of taller cultivars, especially large-flowered ones, to sturdy canes for support.
Dahlias dislike shade, as well as cold, wet soil and very dry sites. They’re not hardy, so in all but the mildest areas of the UK it is best to dig up the root tubers and store them in a frost-free place over winter. These tall and often top-heavy plants don’t stand up well to strong winds, so need staking.
Did you know?
If you keep cutting flowers for indoor use, your plants will keep producing more until the first frosts. Only cut the flowers when fully opened, as closed buds don’t open after picking. Brown petals at the back of opened flowers are a sign of old age, so avoid these for the longest vase life.
The Royal Horticultural Society is the UK’s leading gardening charity. We aim to enrich everyone’s life through plants, and make the UK a greener and more beautiful place.