How to Grow Sunflower
Helianthus annuus
Sunflowers are easy to grow and excellent for pollinators and children's gardens. Sow indoors in April or direct outdoors from May once the soil has warmed. Protect seedlings from slugs — they are the biggest threat and can destroy plants overnight. Stake tall varieties early to avoid root damage later, and water deeply once or twice a week rather than little and often. For seeds, cut heads when the back turns brown and hang upside down to dry.
When to Start
Sow indoors 3 weeks before last frost, or direct sow outdoors after frost risk has passed and soil reaches 10°C.
Don't know your frost date? Find it here →
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.
Growing Conditions
- Min. soil temperature
- 10°C+
- Germination temperature
- 18–25°C
Enter your last frost date to see your dates
- Sow indoors
- —
- Transplant out
- —
- First harvest
- —
Want your full season plan with reminders? Try Leaftide free
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).
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.
