Dahlia 'Great Hercules' (D) | dahlia 'Great Hercules'

RHS

Bedding Herbaceous Perennial

Buy this from Plant Nurseries
5 Suppliers

A tall, tuberous-rooted perennial to about 1.2m, with mid-green foliage. Large, fully double, slightly ruffled, pale orange flowers, up to 20cm across, with a hint of pink, are produced from midsummer until the first frosts, the long, slightly twisted petals creating a tousled effect

Position

Full sun

Soil Types

Clay, Loam, Sand

Max Height

1-1.5 metres

Max Spread

0.5-1 metres

Size

Time to Maturity: 1–2 years
Max Spread: 0.5-1 metres
Max Height: 1-1.5 metres

Growing Conditions

Clay Loam Sand

Moisture: Moist but well–drained or 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
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, moist but well-drained soil, in full sun. Pinch out growing tips to encourage bushy plants and stake taller dahlias, see staking perennials. Water in dry periods if needed. Lift and store tubers in autumn to replant, or use as a source of cuttings, in spring. See dahlia cultivation, and our video How to plant dahlia tubers and care tips This plant was included in the RHS Dahlia trial 2023-2024 https://www.rhs.org.uk/plants/trials-awards/plant-trial-results/dahlia

Propagation

Propagate by softwood cuttings taken in spring from shoots from stored tubers, or divide the tubers ensuring each division has a viable bud

Suggested planting locations and garden types

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

Pruning

Deadhead spent flowers to encourage further flowering. Cut back to near ground level in autumn, before lifting and storing for the winter

Pests

May be susceptible to aphids, leaf miners, glasshouse red spider mite and slugs. Earwigs sometimes damage blooms. Capsid bug and caterpillars are occasional pests

Diseases

May be susceptible to Powdery mildews in dry conditions. In wet weather grey moulds and other fungal rots can be a problem. Fungal rots can also damage stored tubers. A virus may cause stunting, leaf markings and distortion