BLACK SUNFLOWER GREEN MANURE SEEDS
Botanical Name: Helianthus annuus
Black Sunflower is a fast-growing, deep-rooted green manure and cover crop ideal for Australian gardeners looking to improve soil structure and fertility. With its bold height, weed-suppressing foliage, and ability to attract pollinators, this annual sunflower is both beautiful and beneficial.
Perfect for breaking up compacted ground, adding organic matter, and protecting soil between crops, Black Sunflower green manure is a popular choice for home gardens, orchards, market gardens, and broadacre systems.
- Improves soil structure, aeration, and nutrient content.
- Suppresses weeds with broad-leaf canopy and dense growth.
- Attracts bees and beneficial insects during the flowering phase.
- Deep taproot helps to loosen and condition heavy soils.
- Excellent summer cover crop when slashed before flowering.
Plant Details
- Plant Type: Warm-season annual green manure
- Height: 1.5–2 m at maturity
- Best Use: Soil builder, weed suppression, pollinator support
Sowing Information
- Sow Time by Zone:
Temperate: October–December
Subtropical: September–November
Tropical: November–January
Cool: Late spring–early summer
Arid: Spring–early summer - Germination Time: 7–14 days
- Sowing Depth: 2–3 cm
- Position: Full sun
- Sow Method: Direct into prepared garden beds, paddocks, or rotation zones
- Soil Type: Well-drained, fertile soil (pH 6.0–7.5)
- Spacing: 35–45 cm between plants
🌿 When to Sow Black Sunflower in Your Climate
| Climate Zone | Best Planting Time | Tips |
|---|---|---|
| Temperate | October–December | Sow after final frost; cut back before seed set. |
| Subtropical | September–November | Plant early in spring for vigorous growth and weed control. |
| Tropical | November–January | Sow with start of wet season; monitor waterlogging risk. |
| Cool | Late spring–early summer | Wait for consistent warmth; protect seedlings from slugs. |
| Arid | Spring–early summer | Irrigate during establishment; mulch to retain moisture. |
⚙️ Quick Growing Guide
| Aspect | Details |
|---|---|
| Germination Time | 7–14 days |
| Sowing Depth | 2–3 cm |
| Watering | Moist during germination; low water needs when mature |
| Growth Period | 8–12 weeks |
| Incorporation Timing | Slash before flowering and dig in 3–6 weeks before next planting |
✅ Summary
Black Sunflower green manure seeds offer a dual benefit—improving your soil’s health while creating a beautiful summer display. Their deep taproots break up clay and compacted soils, while dense foliage naturally suppresses weeds. Perfect for regenerative gardening, permaculture plots, and sustainable land care.
Whether you’re growing for soil restoration, weed control, or seasonal fertility, shop our full range of green manure seeds here and add black sunflower to your summer planting rotation.
Looking for SUNFLOWER MICROGREEN SEEDS instead? Click here to purchase seeds suitable for microgreens.