How to Grow Aconitum 'Bressingham Spire'

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Aconitum 'Bressingham Spire'

Aconitum napellus 'Bressingham Spire'

flower

A striking perennial featuring tall, dense spikes of deep violet-blue flowers that bloom in mid to late summer. This cultivar of monkshood is a classic cottage garden plant known for its architectural form and rich color. The plant is highly toxic and requires careful handling, but is rarely browsed by deer or rabbits.

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Example Aconitum 'Bressingham Spire' timeline · Pittsburgh, PA (Zone 6b)

  1. Plant Aconitum 'Bressingham Spire'

    Around Apr 17

    Near Pittsburgh's average last spring frost.

  2. Tend & protect

    Late spring–summer

    Watering, feeding, and pest-watch reminders.

  3. First Aconitum 'Bressingham Spire' blooms

    Mid-to-late summer

    Before the first fall frost (≈ Nov 8)

Sample dates for Pittsburgh, PA. Sign up to get exact Aconitum 'Bressingham Spire' dates for your own zip code.

Growing Conditions

☀️
Sun: Partial shade to full sun; 4-6 hours of sunlight daily; afternoon shade in hot climates
💧
Water: Consistent moisture; keep soil evenly moist but not waterlogged. Water deeply during dry spells. Mulch to retain soil moisture and keep roots cool.
📏
Spacing: 24 inches
📅
Days to maturity: Not applicable (perennial); flowers appear in second year from seed
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Planting depth: Plant crowns at soil surface level; plant seeds 1/4 inch deep

Soil

Type: Well-draining, humus-rich loamy soil
pH: 6.0-7.0
Amendments:
Compost or well-rotted organic matter Peat moss or coconut coir for moisture retention Bone meal for phosphorus

Growing Zones

Find your zone →

Thrives in zones 3-7; prefers cooler climates and may struggle in hot summers

3a 3b 4a 4b 5a 5b 6a 6b 7a 7b

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Growth Stages

1

Seedling/Establishment

First growing season (spring to fall)

Emerge as small seedlings with deeply lobed leaves. First-year plants develop a strong root system.

Keep soil consistently moist. Provide shade cloth in hot regions. Do not disturb roots. Be cautious with handling due to toxicity.

2

Vegetative Growth

Spring (weeks 1-8)

Plants develop clumps of deeply cut, dark green foliage. Stems elongate in spring, reaching 3-5 feet tall.

Stake tall varieties for support, especially in windy locations. Remove dead foliage in autumn. Provide consistent moisture and cool conditions.

3

Flowering

Mid-July to September (8-12 weeks)

Dense spikes of hooded, deep violet-blue flowers emerge on tall stems, creating striking vertical accents in the garden.

Deadhead spent flowers to encourage longer blooming. Support heavy flower spikes with stakes or cages. Keep soil moist during blooming.

4

Seed Development

September to November

Flowers fade and seed pods develop along the spikes if not deadheaded.

Leave some flowers for seeds if self-sowing desired. Cut back to ground level in late fall after frost blackens foliage.

5

Dormancy

November to March

Plant dies back completely to the ground, storing energy in the underground tubers.

Apply winter mulch (3-4 inches) in zones 3-5 for extra protection. No supplemental water needed. Avoid disturbing dormant roots.

Companion Planting

Plan your garden →

Plant with:

Avoid planting near:

Plants susceptible to shade competition (delicate alpines) Edible herbs or vegetables where skin contact occurs

Common Pests

  • Spray with strong water stream; apply neem oil or insecticidal soap in severe infestations

  • Spray with water; use insecticidal soap or neem oil; encourage beneficial insects like ladybugs

  • and

    Remove manually; use copper tape or diatomaceous earth barriers; apply slug baits cautiously around non-target plants

  • Ensure excellent drainage; avoid waterlogging; remove affected plants; do not overhead water

Uses

🍳

Not for consumption

Culinary

Aconitum is extremely toxic and should never be ingested or used in any food preparation. All parts of the plant are poisonous. [source]

🏠

Cut flower arrangement

Household

Tall spikes of deep blue flowers are prized for summer and late-season flower arrangements. The vertical form provides excellent structure and drama in floral designs. [source]

🎨

Garden architecture and design

Craft

'Bressingham Spire' is valued for its striking vertical accent in cottage gardens, border plantings, and Victorian-style gardens. The cultivar's dense spike form makes it a focal point in landscape design. [source]

🦋

Pollinator support

Wildlife

The tubular hooded flowers attract bumblebees and other long-tongued bees, providing late-season nectar when other flowers are scarce. [source]

💊

Historical pharmaceutical use

Medicinal

Aconitine has been studied in traditional medicine and modern pharmacology, though it is extremely dangerous and no longer recommended for home medicinal use. Handled only by professionals in controlled settings. [source]

This is not medical advice. LizPlants is not a medical resource. Always consult a qualified healthcare professional before using plants medicinally.

Harvest Tips

Cut flowers for arrangement when the bottom third of the spike has opened. Place cut stems in cool water immediately. Aconitum is not harvested for consumption due to extreme toxicity. Seeds can be collected in fall by allowing pods to dry on the plant, then storing in a cool, dry location.

Fun Facts

  • 🌱 Aconitum is one of the most toxic plants in temperate gardens—all parts contain aconitine alkaloids, sometimes called 'Queen of Poisons.' Even touching the plant with bare skin can cause dermatitis in sensitive individuals, and ingestion of tiny amounts can be fatal.
  • 🌱 'Bressingham Spire' was named after the famous Bressingham Gardens in Norfolk, England, where many superior plant cultivars were bred and selected by Alan Bloom.
  • 🌱 Monkshood gets its common name from the distinctive hooded shape of the flowers, which resembles a monk's cowl. In medieval times, it was used as a weapon poison on arrow tips.

Gardening Terms

New to gardening? Learn about terms used in this guide:

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