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How to Grow Ammi majus

Ammi majus

Hardy Cool Season Continuous Harvest

When to Start

Direct sow outdoors as soon as soil reaches 5°C — typically early to mid spring. Can also be started indoors 4 weeks earlier for a head start.

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Growth Stages

Sow seeds
Germination ~14d
Flowering ~85d

Approximate days from start

Care Essentials

  • Rarely needed. Thrives in average to poor, well-drained soil — rich soil produces lush leafy growth at the expense of flowers.
  • THE cut flower filler for florists and flower farmers. Caution — the sap is phototoxic and can cause skin irritation in sunlight; wear gloves when handling. Autumn sowing gives much bigger, earlier plants than spring sowing.

Companion Planting

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Growing Conditions

Min. soil temperature: 5°C+
Germination temperature: 15–20°C

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Spacing & Planting

Plant spacing 25 cm
Row spacing 35 cm
Sow depth 0 cm
Mature height 90 cm
Mature spread 30 cm

Tall plant reaching 90-120 cm. Pinch out growing tips when 15 cm tall to encourage branching and more stems. May need support with netting or grow-through rings in exposed sites.

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Care Guide

Feeding
Rarely needed. Thrives in average to poor, well-drained soil — rich soil produces lush leafy growth at the expense of flowers.
Watch for
  • Aphids
  • Carrot fly
  • Powdery mildew

Pests & Diseases

Pest Aphids

Identification: Clusters of small green or black insects on shoot tips and flower buds, causing distorted growth and sticky honeydew

Organic treatment:
  • Blast off with a strong jet of water
  • Spray with fatty acid-based insecticide
  • Encourage ladybirds, lacewings and hoverflies
Chemical treatment:
  • Spray with a contact insecticide containing deltamethrin or lambda-cyhalothrin
Pest Carrot Fly

Identification: Rusty-brown tunnels in stems near soil level; wilting and yellowing of lower leaves; small white maggots visible if stems are cut open

Organic treatment:
  • Grow under fine insect-proof mesh
  • Avoid sowing near carrots or parsnips
  • Delay spring sowing until after the first carrot fly generation (late May)
Chemical treatment:
  • Soil drench with an approved insecticide at sowing time
Disease Powdery Mildew

Symptoms: White powdery coating on leaves and stems, causing yellowing and reduced vigour, especially later in the season

Treatment: Remove badly affected leaves. Spray with a fungicide if severe. Improve airflow around plants

Prevention: Space plants well, avoid overhead watering, and water at the base in the morning

Growing Conditions

Min. soil temperature5°C
Germination temperature15–20°C
Base growth temperature5°C
Min. daylength to start10h
Photoperiod sensitivityday neutral

Frequently Asked Questions

How far apart should I plant Ammi majus?
Plant Ammi majus 25cm apart with 35cm between rows.
When does Ammi majus flower?
Ammi majus typically flowers approximately 70 days after transplanting.
Is Ammi majus frost hardy?
Ammi majus is classified as Hardy.

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