Dahlias in Trioslaig
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.
Growing Guide
Step-by-step instructions for growing Dahlia
Planting Calendar
Growing Guide for
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.
Start Tubers Indoors
5 May – 19 MayPlace tubers in trays with moist compost, eye-side up, and cover lightly. Keep at in a bright spot indoors from 5th May - 19th May. Water sparingly until shoots appear.
Pot On Shoots
2 Jun – 9 JunOnce shoots are tall, pot each tuber into individual containers with multi-purpose compost from 2nd June - 9th June. Grow on in a bright, frost-free place.
Harden Off Plants
23 Jun – 30 JunGradually acclimatise plants to outdoor conditions over 10-14 days from 23rd June - 30th June. Place outside during the day and bring in at night, avoiding frost.
Plant Outdoors
30 Jun – 14 JulTransplant into well-drained, fertile soil in full sun after frosts from 30th June - 14th July. Space plants apart and water in well. Use fleece if cold nights are forecast.
Support and Pinch
14 Jul – 21 JulInsert stakes at planting to support tall stems. Pinch out the growing tip when plants reach to encourage bushiness from 14th July - 21st July.
Feed and Water
18 Jun – 21 Julevery 2 weeksWater regularly to keep soil moist, especially in dry spells. Feed every 14 days with a high-potash fertiliser from 18th June to boost flowering. Stop feeding by 21st July.
Deadhead Regularly
25 Jun – 1 SeptRemove spent flowers weekly from 25th June to encourage continuous blooms. Cut back to a leaf joint to promote new buds.
Lift and Store Tubers
9 Jul – 23 JulAfter the first frost blackens foliage, cut stems back and carefully lift tubers from 9th July - 23rd July. Dry, label, and store in frost-free conditions in dry compost or sand over winter.
Companion Plants
Tap a plant to see why it works (or doesn't) with Dahlia.
Good companions
Plants to avoid
Why companion planting matters
Companion planting can deter pests, improve pollination, and make better use of space. Some plants confuse pests or attract beneficial insects; others improve soil or offer shade to neighbours that need it.
Suggested Varieties
Popular varieties of Dahlia to consider
Bishop of Llandaff
A classic variety with dark foliage and bright red flowers, ideal for borders and excellent for pollinators.
Café au Lait
Popular for weddings, with large, creamy-pink blooms that can reach up to 25cm across.
Happy Days
A compact bedding type, perfect for containers, with prolific flowering in mixed colours.
Related Plants
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Brussels Sprouts
Brussels sprouts are a hardy winter brassica (cabbage family) that form sturdy, leafy stems often around 60–90cm tall. They produce edible mini-cabbage buds along the stem from autumn through winter. Thanks to their cold tolerance, sprouts remain productive into late winter, and frost actually improves their sweetness.
Calabrese
Calabrese (broccoli) produces a large central head of tightly-packed green buds, followed by smaller side-shoots after the main head is cut. It’s a cool-season brassica crop. Grow it in full sun with fertile, well-drained soil and keep plants watered during dry spells. Harvest the heads while firm, then leave the stem in the ground to allow side-shoots to develop.