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Herbaceous Perennial

Delphinium 'Blue Lace'

delphinium 'Blue Lace'

A tall herbaceous perennial with flower spikes reaching up to 1.8m. In summer, densely-packed spires of semi-double sky-blue flowers, some with a lavender pink flush, are held above the deeply-cut, mounded foliage

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Ultimate height

1.5–2.5 metres

Time to ultimate height

2–5 years

Ultimate spread

0.1–0.5 metres

Chalk

Clay

Loam

Sand

Moisture

Moist but well–drained

pH

Acid, Alkaline, Neutral

	Stem	Flower	Foliage	Fruit
Spring
Summer
Autumn
Winter

Full sun

Aspect

West–facing or East–facing or South–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)

Botanical details

Family: Ranunculaceae
Native to GB / Ireland: 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 a fertile, well-drained soil in full sun; shelter from strong winds and stake well (see staking perennials). Apply a balanced liquid every couple of weeks in the growing season. For the best flower spikes thin shoots when 7cm high to leave a minimum of 2-3 shoots on young plants and 5-7 shoots on established plants. See staking: perennials and delphinium cultivation for further advice

Propagation

Propagate by taking pencil thick basal cuttings in early spring

Suggested planting locations and garden types

Cottage and informal garden
Cut flowers
Flower borders and beds
Wall side borders

Pruning

Deadhead spent flower spikes. After flowering, cut down all growth to ground level. If fed and watered well, a second flush of flowers may be produced in autumn

Pests

May be susceptible to aphids, earwigs, delphinium leaf miner, delphinium moth caterpillars, slugs, snails and caterpillars

Diseases

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

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