Delphiniums

Delphinium elatum

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verifiedReviewed by the GreenScout Team

Delphiniums are iconic tall perennials with spectacular columnar flower spikes in shades of blue, purple, white, and pink. These majestic plants can reach 4–6 feet tall and create dramatic focal points in borders and cutting gardens. They require cool climates and careful staking for best results.

Common Problems

Select the problem your Delphiniums is experiencing to get a treatment guide.

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Powdery Mildewchevron_right

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Root Rotchevron_right

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Yellow Leaveschevron_right

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Wiltingchevron_right

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Black Spotschevron_right

Care Guide

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Light

Full sun (6–8 hours daily) for optimal flowering; afternoon shade beneficial in hot climates.

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Water

Keep soil consistently moist but not waterlogged; excellent drainage essential. Water at base to prevent foliar diseases.

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Soil

Rich, well-draining soil amended with compost or leaf mold. Prefers slightly alkaline to neutral pH (6.5–7.5).

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Fertiliser

Feed monthly with balanced or slightly lower-nitrogen fertilizer during growing season. Avoid excessive nitrogen.

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Temperature

Prefers cool climates (50–70°F); struggles above 75°F. Hardy to zone 2 (–50°F) but often short-lived in hot regions.

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Humidity

Moderate humidity with excellent air circulation to prevent powdery mildew and crown rot.

Toxicity

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All parts are highly toxic, containing cardiac glycosides and other alkaloids. Dangerous to cats, dogs, and children; avoid ingestion.

Common Diseases

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Common Pests

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Seasonal Care

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Resume regular watering and feeding as growth picks up.

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Peak growing season. Water and feed regularly.

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Reduce watering as growth slows. Stop heavy feeding.

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Minimal watering and feeding. Protect from frost if needed.

Frequently Asked Questions

Why do my Delphiniums struggle in hot summers?

They prefer cool climates and struggle above 75°F — in warmer regions they're often short-lived even though they're hardy to zone 2 in cold weather.

Is it safe to grow Delphiniums around children or pets?

No — all parts are highly toxic, containing cardiac glycosides and other alkaloids, so site them away from areas where kids or pets might handle or chew the plants.