1. Crop Overview

• Common names: Sunflower, surajmukhi
• Scientific name: Helianthus annuus L.
• Crop type: Warm-season annual oilseed; day-neutral; frost-sensitive; tap-rooted
• End-use types: Oilseed (35–50% oil), confectionery / hulling (large striped seed), bird-feed, ornamental cut-flower
• Heliotropism: Young flower buds and heads track the sun east-to-west during the day; at full bloom the head fixes facing east and stays there until harvest.
• Pollination: Largely cross-pollinated by honey bees and other insects; modern hybrids are partially self-fertile but yield far more with bee activity.

2. Climatic Requirements

• Temperature: Optimum 20–25 °C; grows in the range 15–30 °C. Above 35 °C at flowering causes pollen sterility and poor seed set; below 8 °C growth stalls.
• Daylength: Day-neutral — can be grown in spring, kharif (monsoon) and rabi (winter) wherever frost-free.
• Sunshine: Needs full sun; partial shade reduces head size, oil content and seed fill.
• Rainfall: 500–800 mm well-distributed; sensitive to waterlogging but also drought-tolerant once the tap root is established.
• Wind: Strong wind at flowering and grain-fill can cause lodging of heavy heads — avoid very exposed fields or use windbreaks.

3. Soil & Field Preparation

• Soil: Well-drained deep sandy-loam to clay-loam; tolerates a wide pH range of 6.0–8.0 but optimum is 6.5–7.5.
• Avoid heavy waterlogged soils and highly acidic (<5.5) or strongly saline soils.
• Plough deeply once (the tap root grows 1.5–2 m), followed by 2–3 harrowings to a fine, level tilth.
• Incorporate 10–15 t/ha well-decomposed FYM or compost at the last ploughing.
• Form ridges or raised beds in rainfed and irrigated systems for drainage and easy hoeing.

4. Sowing & Crop Establishment

• Sunflower is direct-sown; no nursery is required.
• Sowing depth: 3–5 cm; deeper sowing in dry soil, shallower in moist or heavy soil.
• Method: Dibbling, seed-drill or precision planter. Maintain 1 seed per hill at the correct depth and spacing for uniform stand.
• Ensure adequate soil moisture at sowing; a pre-sowing irrigation 4–5 days before planting gives the best germination.
• Optimum germination: 4–7 days at soil temperature above 18 °C.

5. Seed Rate & Seed Treatment

Seed rate

• Hybrid: 5–6 kg/ha
• Open-pollinated varieties (OPV): 8–10 kg/ha
• Confectionery / large-seeded types: 6–7 kg/ha (lower plant population, larger seed)

Seed treatment

• Treat seed with Trichoderma viride @ 4 g/kg or Thiram / Captan @ 2–3 g/kg to control damping-off, seed rot and seedling blight.
• For downy-mildew-prone areas, use Metalaxyl @ 6 g/kg of seed.
• Add a biofertilizer (Azospirillum + PSB @ 25 g/kg seed) before sowing in low-fertility soils.

6. Spacing & Plant Population

• Oilseed hybrids: 60 × 30 cm or 45 × 30 cm (about 55,000–75,000 plants/ha)
• Confectionery types: 75 × 30 cm (about 45,000 plants/ha) — lower density gives larger heads and seed
• Rainfed / low-rainfall areas: wider spacing (60 × 45 cm) to reduce moisture competition
• Irrigated / high-input: tighter spacing (45 × 30 cm) for maximum yield per hectare
• Thin to one plant per hill 12–15 days after emergence; fill gaps within the first 10 days.

7. Pollination Management

This is the single most important section for sunflower yield. Even the best hybrid and the best agronomy will under-perform if bee activity is low at flowering, because seed set on the outer ring of the head and overall seed fill depend on bee visits.

• Honey bee colonies: Place 4–5 colonies / ha at the field edge, 3–5 days before flowering begins.
• Hand pollination: Where bees are scarce, rub two heads together gently or pass a soft pad / cotton ball across the disc flowers in the morning (8–11 am) every other day during flowering.
• Avoid insecticide sprays during flowering hours. If a spray is essential, apply only in the late evening with a bee-safe product.
• Provide a water source near the field for bees during peak flowering.
• Maintain mixed flowering plants on the field bunds to keep pollinator populations year-round.

8. Nutrient Management (per hectare)

Indicative dose — adjust to soil test report and local recommendation:

9. Irrigation

• Sunflower needs 4–6 irrigations in the irrigated rabi / summer crop; rainfed kharif crops need 1–2 protective irrigations during dry spells.
• Critical stages for irrigation: bud initiation (35–40 DAS), flowering (50–65 DAS), and seed-fill (70–85 DAS). Stress at these stages cuts yield sharply.
• Avoid waterlogging — the tap root rots quickly in standing water.
• Drip or furrow irrigation is preferable to flood irrigation, especially on heavy soils.
• Stop irrigation 10–12 days before harvest to help heads dry down.

10. Weed & Intercultural Care

• Keep the field weed-free for the first 35–45 days — this is the most critical period for weed competition.
• Two hand-weedings (at 20 and 40 DAS) plus an inter-row hoeing are usually sufficient.
• Earthing-up at 30–35 days strengthens the plant base against lodging when heads become heavy.
• Pre-emergence herbicide (e.g. pendimethalin 1.0 kg a.i./ha) can be used as per local recommendation in large-scale plantings.
• Avoid deep cultivation late in the crop — it damages surface feeder roots.

11. Plant Protection — Pests

12. Plant Protection — Diseases

13. Physiological Disorders

• Centre-seed sterility / unfilled head: caused by boron deficiency, poor bee pollination, or extreme heat at flowering — fix with boron application, place bee colonies, and shift sowing date away from the hottest window.
• Lodging: heavy heads on weak stems collapse in wind or after irrigation — manage with proper spacing, balanced N (excess N causes lodging), earthing-up and avoiding late heavy irrigation.
• Head bending / drooping: normal at maturity, but premature severe bending may indicate stalk weakness from nutrient imbalance or charcoal rot.
• Sun-scorch / scald on petals or seed: in extreme heat, especially in late-sown crops — choose heat-tolerant hybrids and shift sowing time.

14. Harvesting & Post-Harvest

• Maturity signs: back of the head turns lemon-yellow then brown; ray petals dry and fall; bracts turn yellow-brown; seed moisture is around 18–20%.
• Cut the head with 10–15 cm of stalk; stack with heads facing in to protect seed from birds and weather.
• Field-dry the heads for 4–6 days; thresh by gentle beating or with a sunflower thresher.
• Clean and dry seed to 9–10% moisture before storage; below 9% for long-term oilseed storage.
• Yield: hybrids 2.5–3.5 t/ha (up to 4 t/ha under best management); OPV 1.5–2.0 t/ha; confectionery 1.5–2.5 t/ha.
• Store cleaned seed in moisture-proof bags in a cool, dry, ventilated store; rotate stock.

15. Country-Wise Climate & Sowing Guide

Sunflower can be grown almost anywhere with a frost-free window of 90–120 days. The key is to schedule flowering away from extreme heat (>35 °C) and heavy rain, both of which damage pollination and the head. Windows below are indicative — adjust to local altitude and micro-climate.

16. Frequently Asked Questions