How to Grow Sunflower
Helianthus annuus
When to Start
Sow indoors 3 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 10°C.
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Growth Stages
Approximate days from start
Care Essentials
- Balanced feed at planting. Liquid feed weekly once flower buds form for giant varieties.
- Excellent for pollinators and children's gardens. Tall varieties need staking in exposed positions.
Companion Planting
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Growing Conditions
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- Sow indoors
- —
- Transplant out
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- First harvest
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Spacing & Planting
| Plant spacing | 50 cm |
| Row spacing | 75 cm |
| Sow depth | 2.5 cm |
| Mature height | 200 cm |
| Mature spread | 60 cm |
For large, single-stemmed varieties grown for seeds or large heads. Multi-branching or dwarf varieties can be planted closer (30-40 cm).
Care Guide
- Feeding
- Balanced feed at planting. Liquid feed weekly once flower buds form for giant varieties.
- Watch for
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- Slugs on seedlings
- Birds (eat seeds)
- Aphids
- Grey mould
Pests & Diseases
Pest Slugs and Snails
Identification: Seedlings eaten off at ground level; ragged holes in young leaves; slime trails around plants
- Apply organic slug pellets (ferric phosphate based) around seedlings from the moment they emerge
- Protect individual seedlings with cut plastic bottles as cloches
- Hand-pick at dusk; use beer traps
- Apply ferric phosphate slug pellets around vulnerable seedlings
Pest Aphids
Identification: Clusters of green or black insects on stems, leaf undersides, and developing flower buds; sticky honeydew; ants farming colonies
- Blast off with a strong jet of water
- Spray with insecticidal soap
- Encourage ladybirds, lacewings, and hoverflies
- Spray with a contact insecticide containing pyrethrins; avoid spraying open flowers to protect pollinators
Pest Birds
Identification: Seeds dug up after sowing; ripe seed heads stripped or damaged; birds perching on flower heads
- Net seed heads with fine mesh or old tights as seeds begin to ripen
- Cover newly sown areas with netting until seedlings are established
- Use bird scarers or reflective tape near plants
Disease Grey Mould (Botrytis) Botrytis cinerea
Symptoms: Fuzzy grey mould on flower heads, stems, and leaves; brown, water-soaked patches; flower heads may rot from the back
Treatment: Remove affected plant parts; improve air circulation; avoid overhead watering
Prevention: Space plants well; water at the base; avoid wetting flower heads; remove spent flowers promptly
Disease Powdery Mildew Golovinomyces cichoracearum
Symptoms: White, powdery coating on leaves; leaves yellow and die back; reduced plant vigour
Treatment: Remove badly affected leaves; spray with a sulphur-based fungicide or potassium bicarbonate solution
Prevention: Space plants for good airflow; water at the base; choose resistant varieties
Disease Sclerotinia Stem Rot Sclerotinia sclerotiorum
Symptoms: White, cottony fungal growth on stems; dark, hard sclerotia form inside stems; plants wilt and collapse above the infection point
Treatment: Remove and destroy affected plants; do not compost
Prevention: Rotate crops; avoid planting sunflowers in the same spot year after year; ensure good drainage
Growing Conditions
| Min. soil temperature | 10°C |
| Germination temperature | 18–25°C |
| Base growth temperature | 8°C |
| Min. daylength to start | 10.5h |
| Photoperiod sensitivity | day neutral |
Frequently Asked Questions
- How far apart should I plant Sunflower?
- Plant Sunflower 50cm apart with 75cm between rows.
- When does Sunflower flower?
- Sunflower typically flowers approximately 65 days after transplanting.
- Is Sunflower frost hardy?
- Sunflower is classified as Half Hardy.
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