
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.
The most common UK method, starting tubers indoors in spring and planting out after frosts for summer blooms.
Place tubers in trays with moist compost, eye-side up, and cover lightly. Keep at in a bright spot indoors from 8th March - 22nd March. Water sparingly until shoots appear.
Once shoots are tall, pot each tuber into individual containers with multi-purpose compost from 5th April - 12th April. Grow on in a bright, frost-free place.
Gradually acclimatise plants to outdoor conditions over 10-14 days from 26th April - 3rd May. Place outside during the day and bring in at night, avoiding frost.
Transplant into well-drained, fertile soil in full sun after frosts from 3rd May - 17th May. Space plants apart and water in well. Use fleece if cold nights are forecast.
Insert stakes at planting to support tall stems. Pinch out the growing tip when plants reach to encourage bushiness from 17th May - 24th May.
Water regularly to keep soil moist, especially in dry spells. Feed every 14 days with a high-potash fertiliser from 24th May to boost flowering. Stop feeding by 14th September.
Remove spent flowers weekly from 5th July to encourage continuous blooms. Cut back to a leaf joint to promote new buds.
After the first frost blackens foliage, cut stems back and carefully lift tubers from 5th October - 19th October. Dry, label, and store in frost-free conditions in dry compost or sand over winter.
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.