Sunflowers (Helianthus annuus) come in various sizes, from dwarf varieties (1-2 feet tall) to towering giants (12+ feet). For beginners, smaller or medium-sized cultivars like 'Sunspot' or 'Autumn Beauty' are easier to manage. Consider your space and sunlight availability—sunflowers thrive in full sun (6-8 hours daily).
Sunflowers prefer well-draining, loamy soil with a pH of 6.0–7.5. Amend heavy clay or sandy soil with compost for nutrients. Avoid waterlogged conditions, as roots are prone to rot. Loosen the soil to a depth of 2 feet for taller varieties to support deep root growth.
Sow seeds directly outdoors after the last frost, 1 inch deep and 6 inches apart (18 inches for large varieties). Thin seedlings to 12–18 inches apart once they reach 6 inches tall. For continuous blooms, stagger planting every 2–3 weeks in spring.
Water seedlings daily for the first 1–2 weeks to establish roots. Mature sunflowers need 1–2 inches of water weekly, focusing on the base to avoid fungal issues. Reduce watering as blooms form to prevent stem weakness.
Use a balanced fertilizer (10-10-10) at planting and again when plants are 2 feet tall. Avoid high-nitrogen fertilizers, which promote leafy growth over flowers. Organic options like compost tea work well for steady nutrient release.
Tall varieties may require staking to prevent wind damage. Tie stems loosely to stakes with soft cloth, allowing slight movement for natural strengthening. Plant near fences or walls for additional support.
Aphids, slugs, and birds are common threats. Use insecticidal soap for aphids, beer traps for slugs, and netting to protect seeds. Rotate crops yearly to avoid soil-borne diseases like mildew.
Sunflowers attract bees and butterflies, vital for pollination. Avoid pesticides during bloom. Leave some flower heads to dry on stalks—birds love the seeds, and they self-sow for next season.
Cut flower heads when the back turns brown and seeds are plump. Hang upside-down in a dry, ventilated space. Rub seeds loose once fully dry, and store in airtight containers for eating or replanting.
