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Herbaceous Perennial

Dahlia 'Sarah' (S-c)
  • RHS Plants for pollinators

A tuberous-rooted perennial to about 70cm, with dark bronze-green foliage, blooming from mid-summer until the first frosts. Single flowers have broad, rounded, bright red petals, with a dark brown central disc opening to orange

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Size
Ultimate height
0.5–1 metres
Time to ultimate height
1 year
Ultimate spread
0.1–0.5 metres
Growing conditions
Clay
Loam
Sand
Moisture
Moist but well–drained
pH
Acid, Alkaline, Neutral
Colour & scent
StemFlowerFoliageFruit
Spring Bronze Green
Summer Red Bronze Green
Autumn Red Bronze Green
Winter
Position
  • Full sun
Aspect

South–facing or West–facing

Exposure
Sheltered
Hardiness
H3
Botanical details
Family
Asteraceae
Native to the UK
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

Not established

Horticultural Group
Semi-cactus dahlias have fully double flowerheads with narrow, pointed, straight or incurved ray florets broader at the base

How to grow

Cultivation

Grow in full sun, in fertile, humus-rich, well-drained soil enriched with organic matter and general-purpose fertiliser. Pinch out growing tips to encourage bushy plants, and stake. Water freely in dry periods. Lift and store tubers in autumn to replant, or use as a source of cuttings, in spring. See dahlia cultivation

Propagation

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

Suggested planting locations and garden types
  • City and courtyard gardens
  • Cottage and informal garden
  • Wildlife gardens
  • Cut flowers
  • Flower borders and beds
Pruning

Deadhead to prolong flowering. Cut back to near ground level in autumn, once frost has damaged foliage, before lifting and storing for the winter

Pests

May be susceptible to aphids, capsid bugs, caterpillars, earwigs nibbling flowers, glasshouse red spider mite and slugs

Diseases

May be susceptible to powdery mildews in dry conditions, fungal rots including grey mould in wet conditions and in storage, and a virus that causes stunting, leaf markings and distortion

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