Dahlia 'AC Dark Horse' (D) | dahlia 'AC Dark Horse'

Herbaceous Perennial Bedding

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A bushy, tuberous perennial to around 1m high, with serrated green leaves. Decorative, double flowers to 20cm across, with deep pink petals touched with white at the tips and silvery violet on the undersides, are produced from late summer to early autumn

Position

Full sun

Soil Types

Chalk, Clay, Loam, Sand

Max Height

0.5-1 metres

Max Spread

0.1-0.5 metres

Size

Time to Maturity: 1–2 years
Max Spread: 0.1-0.5 metres
Max Height: 0.5-1 metres

Growing Conditions

Chalk Clay Loam Sand

Moisture: Moist but well–drained
pH: Acid or Alkaline or Neutral

Position

Full sun

Aspect: South–facing or West–facing
Exposure: Sheltered
Hardiness

Hardiness Ratings

All ratings refer to the UK growing conditions unless otherwise stated. Minimum temperature ranges (in degrees C) are shown in brackets

H1A: under glass all year (>15C)
H1B: can be grown outside in the summer (10 - 15)
H1C: can be grown outside in the summer (5 - 10)
H2: tolerant of low temperatures, but not surviving being frozen (1 to 5)
H3: hardy in coastal and relatively mild parts of the UK (-5 to 1)
H4: hardy through most of the UK (-10 to -5)
H5: hardy in most places throughout the UK even in severe winters (-15 to -10)
H6: hardy in all of UK and northern Europe (-20 to -15)
H7: hardy in the severest European continental climates (< -20): H3

Colour & Scent

Season	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Botanical Details

Family: Asteraceae
Native to GB/Ireland: No
Foliage: Deciduous
Habit: Clump forming, Bushy
Genus: Dahlia are tuberous rooted perennials with pinnately divided leaves and showy flowerheads, double in many cultivars, in summer and autumn
Name Status: Accepted
Horticultural Group

Horticultural Classification Codes

Horticultural Classification Codes are often given to genera which have a large number of species or cultivars. They are used to categorise cultivated plants based on specific, shared characteristics such as shape, colour, size or flowering time, and can be displayed as letters or numbers

For example:
Dahlia ‘Sunset Kate (Sin) = Single flower
Rosa ‘Marigold’ (HT) = Hybrid Tea: Decorative dahlias have fully double flowerheads with flat or slightly incurved florets

How to Grow

Cultivation

Grow in fertile, humus-rich, well-drained soil, in full sun. Pinch out growing tips to encourage bushy plants. Plants will need support, see staking perennials. Water if needed in dry periods. Lift and store tubers in autumn, particularly in heavy soils, or mulch well to protect from frosts. See dahlia cultivation, and our video How to plant dahlia tubers and care tips, for more advice

Propagation

Propagate by softwood cuttings, taken in spring from shoots from stored tubers, or by division, ensuring each tuber has at least one viable bud

Suggested planting locations and garden types

City and courtyard gardens
Cottage and informal garden
Patio and container plants
Bedding
Cut flowers
Flower borders and beds

Pruning

Deadhead to prolong flowering. Cut back to near ground level in the autumn

Pests

May be susceptible to aphids, capsid bugs, caterpillars, leaf miners, glasshouse red spider mite and slugs. Earwigs sometimes damage blooms

Diseases

May be susceptible to powdery mildews in dry conditions, and to grey moulds and other fungal rots in wet weather. Virus diseases may cause stunting, leaf markings and distortion. Fungal rots can also damage stored tubers