When to plant
Sow direct after last frost when soil is warm. Sunflowers grow quickly (60–90 days) and are frost-tender. For an extended display, succession sow every 3 weeks from late spring through early summer.
Soil & site
Sunflowers are undemanding and grow in most soils. They thrive in well-drained soil of average fertility — too rich soil produces more leaves than flowers. Full sun is essential. They are drought-tolerant once established.
Feeding
Light feeder once established. A single application of balanced fertilizer at planting is usually sufficient. Avoid high-phosphorus fertilizers which can limit micronutrient uptake in sunflowers.
Common problems
Cutworms at seedling stage — place a cardboard collar around the stem at soil level. Aphid clusters on stems — spray with water. Downy mildew in cool, wet weather. Birds attacking ripening seeds — cover the head with a paper bag or netting once petals fall.
When to harvest
For cut flowers, harvest when the bud is just beginning to open (showing colour but not fully open). For seeds, harvest when the back of the head turns from green to yellow to brown, the petals have fallen, and the seeds look plump and striped.
How to harvest
For cut flowers: cut stems at a 45° angle early in the morning, place immediately in water. For seeds: cut the head with 30 cm of stem when the back is brown. Hang upside down in a paper bag in a dry, ventilated spot for 2–3 weeks. Rub seeds out of the head when completely dry.
Storage & use
Dried sunflower seeds keep in an airtight container in a cool, dry place for up to a year. Roast at 160°C for 15–20 minutes for snacking. Store-bought sunflower oil can be made with a cold press but requires specialised equipment.
Companion planting
Sunflowers attract pollinators and provide beneficial shade for heat-sensitive crops.
Useful for growing sunflower
A few things that make this one easier — chosen for this plant, not a generic list.
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