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How to Grow Ranunculus

Ranunculus asiaticus

Half Hardy Cool Season Continuous Harvest

When to Start

Best started from plugs, corms, or slips. Pot up indoors 9 weeks before last frost, then plant out once soil reaches 5°C.

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Growth Stages

Flowering ~75d

Approximate days from start

Care Essentials

  • Balanced liquid feed fortnightly once growth is established. Switch to high-potash feed when buds appear.
  • Ranunculus grow from dried corms that must be soaked in cool water for 3-4 hours before planting. They prefer a cool start and flower best in spring before summer heat arrives. In mild areas, autumn planting gives the earliest blooms.

Companion Planting

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Growing Conditions

Min. soil temperature: 5°C+
Germination temperature: 10–15°C

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Spacing & Planting

Plant spacing 20 cm
Row spacing 30 cm
Sow depth 5 cm
Mature height 40 cm
Mature spread 20 cm

Space corms 15-20cm apart in rows 30cm apart. Plant with claws pointing downward, 5cm deep. Close spacing helps support stems and gives a fuller display.

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Care Guide

Feeding
Balanced liquid feed fortnightly once growth is established. Switch to high-potash feed when buds appear.
Watch for
  • Aphids
  • Slugs and snails
  • Botrytis
  • Powdery mildew

Pests & Diseases

Pest Aphids

Identification: Clusters of small green insects on shoot tips and developing buds, causing distorted growth and sticky honeydew.

Organic treatment:
  • Squash by hand or blast off with a gentle water spray
  • Spray with fatty acid-based insecticide
  • Encourage ladybirds, lacewings and hoverflies
Chemical treatment:
  • Spray with a contact insecticide containing deltamethrin
Pest Slugs and Snails

Identification: Irregular holes chewed in young leaves and shoots. Slime trails visible around plants, especially in the morning.

Organic treatment:
  • Apply organic slug pellets (ferric phosphate) around emerging shoots
  • Use copper tape barriers around containers
  • Encourage hedgehogs, frogs and ground beetles
Chemical treatment:
  • Ferric phosphate-based pellets
Disease Grey Mould (Botrytis) Botrytis cinerea

Symptoms: Fuzzy grey mould on petals, stems and leaves. Buds may rot before opening. Corms can rot in storage.

Treatment: Remove and destroy affected parts promptly. Improve ventilation and reduce humidity.

Prevention: Space plants well for airflow. Avoid overhead watering. Ensure corms are thoroughly dried before storage.

Disease Powdery Mildew

Symptoms: White powdery coating on leaves, causing yellowing and reduced vigour. Flowers may be smaller.

Treatment: Remove badly affected leaves. Spray with a fungicide approved for ornamentals if severe.

Prevention: Space plants well for good airflow. Water at soil level. Avoid drought stress.

Growing Conditions

Min. soil temperature5°C
Germination temperature10–15°C
Base growth temperature5°C
Photoperiod sensitivityday neutral

Frequently Asked Questions

How far apart should I plant Ranunculus?
Plant Ranunculus 20cm apart with 30cm between rows.
When does Ranunculus flower?
Ranunculus typically flowers approximately 75 days after transplanting.
Is Ranunculus frost hardy?
Ranunculus is classified as Half Hardy.

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