
Dahlia pinnata
Show-stopping tuberous perennials that provide a spectacular display of colour from mid-summer right up until the first frosts. Ranging from enormous 'dinner plate' blooms to intricate pompoms and open-centred varieties that bees adore, they are a staple of the late summer UK garden.
Step-by-step instructions for growing Dahlia
Change the guide to see different planting timelines and tips.
Growing dahlias from seed for bedding varieties, sown indoors in early spring for summer flowers.
Sow seeds thinly on the surface of moist seed compost in trays from 18th January - 1st February. Cover lightly and keep at in a bright spot. Germination takes 7-14 days.
Once seedlings have true leaves, transplant into individual pots from 8th February - 15th February. Handle by leaves to avoid stem damage and grow on in good light.
Acclimatise plants to outdoors over 10-14 days from 22nd March - 29th March. Increase exposure gradually, protecting from frost and strong winds.
Transplant into beds or containers after frosts from 29th March - 12th April. Space apart in full sun and water well. Use cloches if needed for early planting.
Pinch out the growing tip when plants are tall from 19th April - 26th April to encourage side shoots and more flowers.
Keep soil consistently moist. Feed with a balanced liquid fertiliser every 14 days from 11th November to support growth and flowering until 26th April.
Remove faded blooms regularly from 18th November to prolong flowering. Snip off just above a leaf node to encourage new buds.
Plants that grow well (or poorly) with Dahlia
Companion planting can help deter pests, improve pollination, enhance growth, and maximize garden space. Some plants release chemicals that repel pests or attract beneficial insects, while others can improve soil quality or provide shade for sensitive plants.
Popular varieties of Dahlia to consider
A classic variety with dark foliage and bright red flowers, ideal for borders and excellent for pollinators.
Popular for weddings, with large, creamy-pink blooms that can reach up to 25cm across.
A compact bedding type, perfect for containers, with prolific flowering in mixed colours.