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Herbaceous Perennial

Delphinium 'Sweetheart'

delphinium 'Sweetheart'

A deciduous, herbaceous perennial that reaches approximately 1.8m in height when in flower. It forms a mound of green, deeply lobed leaves and stately flower stems of numerous rich rose to soft pink flowers with contrasting white centres, from summer to autumn

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Size
Ultimate height
1.5–2.5 metres
Time to ultimate height
1–2 years
Ultimate spread
0.5–1 metres
Growing conditions
Chalk
Loam
Sand
Moisture
Moist but well–drained, Well–drained
pH
Alkaline, Neutral, Acid
Colour & scent
StemFlowerFoliageFruit
Spring Green
Summer Pink White Green
Autumn Pink White Green
Winter
Position
  • Full sun
Aspect

South–facing or West–facing or East–facing

Exposure
Sheltered
Hardiness
H5
Botanical details
Family
Ranunculaceae
Native to the UK
No
Foliage
Deciduous
Habit
Columnar upright
Potentially harmful
Humans/Pets: Harmful if eaten. Wear gloves and other protective equipment when handling. For further information and contact numbers regarding pets, see the HTA guide to potentially harmful plants
Genus

Delphinium can be annuals, biennials or perennials, with palmately lobed basal leaves and showy bowl-shaped flowers in spikes, racemes or panicles

Name status

Accepted

How to grow

Cultivation

Grow in fertile, well-drained soil in full sun. Shelter from strong winds and provide support. Divide every 2-5 years to maintain vigour. See staking: perennials and delphinium cultivation for further advice

Propagation

Propagate by division or by basal softwood cuttings in spring

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

Deadhead main stem after flowering to encourage side shoots to flower. Cut back to ground level in autumn

Pests

May be susceptible to aphids, slugs, snails, leaf miners and caterpillars

Diseases

May be susceptible to powdery mildews, delphinium black blotch, crown rot and viruses

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