How to Grow Ranunculus
Ranunculus asiaticus
Ranunculus are stunning spring-flowering corms producing layers of papery petals in vivid colours. Soak dried corms in cool water for 3-4 hours before planting claws-down, 5cm deep. They thrive in cool conditions and flower best in spring. Start corms in pots under cover in autumn or late winter, then plant out into fertile, well-drained soil in full sun. Feed fortnightly and keep moist but not waterlogged. Cut flowers when buds show colour for excellent vase life. Lift corms after foliage dies back in summer.
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
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.
Growing Conditions
- Min. soil temperature
- 5°C+
- Germination temperature
- 10–15°C
Pet Safety
- Direct sow
- —
- First harvest
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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.
Pests & Diseases
Pest Aphids
Identification: Clusters of small green insects on shoot tips and developing buds, causing distorted growth and sticky honeydew.
- Squash by hand or blast off with a gentle water spray
- Spray with fatty acid-based insecticide
- Encourage ladybirds, lacewings and hoverflies
- 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.
- Apply organic slug pellets (ferric phosphate) around emerging shoots
- Use copper tape barriers around containers
- Encourage hedgehogs, frogs and ground beetles
- 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 temperature | 5°C |
| Germination temperature | 10–15°C |
| Base growth temperature | 5°C |
| Photoperiod sensitivity | day 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.
