Sunflower
Helianthus annuus
Also known asCommon sunflower · Helianthus · Girasol · Tournesol · Sonnenblume
Environment
The bounded range this crop tolerates.
Climate and zones
- USDA zones
- 2–11 (winter low around -46°C)
- Frost
- frost sensitive (dies at first frost)
- Season
- warm (summer, frost-sensitive)
Growing systems
Root mass: heavy. Thin-channel systems can't hold this crop.
Growing media
| Medium | pH effect | Retention | Bacterial surface |
|---|---|---|---|
| Soil-based mix (Potting soil) | varies | high | high |
Nutrient demand by stage
NPK ratios are relative weights. EC targets shift through the plant's life.
| Stage | N | P | K | EC (mS/cm) |
|---|---|---|---|---|
| seedling | 1 | 1 | 1 | 0.8 |
| vegetative | 3 | 1 | 2 | 1.6 |
| flowering | 1 | 1 | 3 | 1.8 |
| fruiting | 1 | 1 | 3 | 1.7 |
Companion-growing notes
- Heavy uptake of nitrogen, potassium. Co-grown crops with the same demand will end up deficient even at "correct" EC.
- Releases root compounds that can inhibit other crops in a shared reservoir.
- High transpiration. Regular reservoir top-ups needed during fruiting.
Aquaponics suitability
Not recommended
Fish waste alone doesn't supply enough of what this crop demands. Grows in hybrid systems with supplemental dosing, but expect active management.
Care notes
Primarily grown hydroponically as a microgreen rather than for seed production (mature sunflowers are too large for most indoor systems). For microgreens: soak black oil sunflower seeds (unhulled) for 8-12 hours, spread densely on a growing pad, keep moist in darkness for 2-3 days, then expose to light. Harvest at 7-12 days when cotyledons are fully expanded and the seed hull has been shed. The thick, crunchy microgreen is one of the most substantial and satisfying microgreen varieties. EC 1.0-1.5 mS/cm for microgreens. pH 6.0-7.0. Temperature: 18–25°C. Moderate light. For full-sized sunflower seed production: outdoor planting only (the plants grow 1.5–3 m tall). Each head produces 1,000-2,000 seeds. Harvest when the back of the head turns brown and seeds are plump. For sunflower sprouts served at restaurants: grow to 10–15 cm with the first true leaves emerging, producing a larger, more substantial product than cotyledon-stage microgreens.
Notable varieties
| Cultivar | Type | Days | Notes |
|---|---|---|---|
| Mammoth Russian | heirloom | 110 | Pre-1880 Russian heirloom, the classic giant-headed home-garden sunflower. Reaches 3-4 m with heads 25-35 cm across. Large striped edible seeds. The variety in every children's garden program. Single head per plant. |
| Giant Grey Stripe | heirloom | 100 | Similar to Mammoth Russian, slightly smaller plant (2.5-3 m), grey-and-white striped seeds. The traditional eating-seed variety in the central US, the kind sold roasted-and-salted at baseball games. Reliable producer. |
| Black Oil | open pollinated | 95 | Commercial oilseed type, the variety pressed for sunflower oil. Black-hulled, thinner-shelled, higher oil content than striped seeds. Also the seed that fills bird-feeder mixes. Plant size 1.5-2 m. |
| Sunspot | open pollinated | 85 | Dwarf cultivar, stays 50-60 cm. Full-sized 25 cm flower head on a short plant, good for borders, container culture, and small gardens. Edible seeds, smaller yield than Mammoth Russian but actually fits in a backyard. |