Sunflower

History

Sunflowers were cultivated by Indigenous people of the Americas for food, oil, and ceremony. Their heliotropic heads follow the sun—a trait that inspired their name. In Australia, they're grown for cheer, height, and wildlife appeal, whether in backyard plots or children's gardens.

Sowing Calendar

GeneralCool/MountainTemperateAridSubtropicalTropical

Best Months to Plant – Sunflower

Climate Zone	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Cool/Mountain	✓										✓	✓
Temperate	✓										✓	✓
Arid	✓	✓							✓	✓	✓	✓
Subtropical	✓	✓							✓	✓	✓	✓
Tropical	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓

Cool/Mountain – Sunflower

Method	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Start in trays	✓										✓	✓
Plant out transplants	✓										✓	✓
Direct sow	✓										✓	✓

Temperate – Sunflower

Method	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Start in trays	✓										✓	✓
Plant out transplants	✓										✓	✓
Direct sow	✓										✓	✓

Arid – Sunflower

Method	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Start in trays	✓	✓							✓	✓	✓	✓
Plant out transplants	✓	✓							✓	✓	✓	✓
Direct sow	✓	✓							✓	✓	✓	✓

Subtropical – Sunflower

Method	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Start in trays	✓	✓							✓	✓	✓	✓
Plant out transplants	✓	✓							✓	✓	✓	✓
Direct sow	✓	✓							✓	✓	✓	✓

Tropical – Sunflower

Method	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
Start in trays	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Plant out transplants	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
Direct sow	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓

Where to Plant

Shady Spots & Herb Gardens

Shady Spots & Herb Gardens
• Areas receiving dappled or indirect sunlight, often near trees or buildings
• Best for shade-tolerant herbs like mint, parsley, or greens like spinach
• Helps prevent sun stress and conserves moisture
• Often used in cooler corners of the garden

Containers & Pots

Containers & Pots
• Portable planting vessels suited for patios, balconies, and small areas
• Provide complete control over soil composition and drainage
• Great for herbs, greens, compact vegetables, or ornamental plants
• Allow plants to be moved to follow sun, shade, or seasonal conditions

Edges

Edges
• Narrow growing spaces along borders, fences, or pathways
• Perfect for low-growing or decorative plants like alyssum or herbs
• Helps soften garden boundaries and attract beneficial insects
• Makes efficient use of underutilised garden space

Borders & Companion Rows

Borders & Companion Rows
• Found along the edges of garden beds, paths, or between main crops
• Ideal for herbs, flowers, or pest-repelling plants that support the main crop
• Helps attract pollinators and beneficial insects
• Makes good use of smaller spaces and improves overall garden health

Pre-treatment

None Identified

There are no pre treatments required for germination.

Sowing Method

Start in Trays

• Fill seed trays or punnets with quality seed-raising mix
• Sow seeds at the correct depth—refer to seed packet for guidance
• Place trays in a warm, sheltered location with good light
• Mist or bottom-water to avoid disturbing small seeds
• Transplant seedlings once they develop 2–4 true leaves

Direct Sow

• Sow seeds directly into prepared garden soil or outdoor containers
• Best for plants that dislike transplanting, such as root vegetables and beans
• Loosen soil and remove weeds before sowing
• Sow at the recommended depth and spacing, then water gently
• Keep the area moist until germination and thin seedlings if needed

Watering

Medium

• Benefits from regular watering, especially during active growth or flowering
• Soil should remain moist but not soggy—allow topsoil to dry slightly between waterings
• Ideal for most vegetables, herbs, and flowering annuals
• More frequent watering may be needed during hot or windy weather
• A layer of mulch can reduce water loss and improve consistency

Fertilisation

Frost

Frost Tolerant

These plants can tolerate light to moderate frosts and may survive through cooler seasons.

Maintenance and Harvesting

Sunflowers need staking for taller varieties and benefit from removing side shoots for larger central blooms. Deadhead to prolong flowering or leave heads for seed collection.

Pests and Diseases

Aphids

Aphids are tiny, soft-bodied insects that cluster on new growth and the undersides of leaves. They suck sap from plants, causing leaves to curl, yellow or become distorted. As they feed, they excrete sticky honeydew that encourages sooty mould, and colonies can build quickly in warm weather.

Start with organic controls: blast colonies off with a firm jet of water, encourage beneficial insects like ladybirds and lacewings, and spray neem oil or insecticidal soap to disrupt feeding. Keep plants well watered and avoid excess nitrogen that promotes soft growth. If pressure remains high, selective chemical sprays can be used sparingly, taking care to protect pollinators and beneficials.

Powdery mildew

Powdery mildew appears as a white, talc‑like coating on leaves and stems. It thrives in warm days, cool nights, and still air, and can weaken plants by reducing photosynthesis, leading to yellowing and early leaf drop.

Prune for airflow, avoid overhead watering, and remove badly affected foliage. Organic sprays such as milk solution, potassium bicarbonate, sulfur, or neem help suppress outbreaks. Chemical fungicides are effective when started early, but use sparingly to preserve beneficial organisms.

Downy mildew

Downy mildew causes pale yellow blotches on upper leaf surfaces with grey‑purple fuzz beneath, spreading fast in cool, moist weather. Heavily infected leaves collapse, slowing growth and yield.

Choose sunny, well‑ventilated positions, water early so foliage dries quickly, and remove infected leaves promptly. Organic options include copper and bio‑fungicides (phosphorous acid salts). For severe pressure, rotate chemical fungicide modes to prevent resistance.

Caterpillars & chewing larvae

Caterpillars and chewing larvae are moth and butterfly young that devour leaves or bore into stems and fruit, reducing growth and spoiling harvests.

Hand‑pick where practical and protect young crops with fine netting. Encourage parasitic wasps and birds. Apply Bacillus thuringiensis (Bt) for an organic, caterpillar‑specific control. Broad‑spectrum insecticides can work but may harm beneficials, so reserve for severe cases.

Rust

Rust diseases produce raised orange‑brown pustules on leaves and stems. Spores disperse easily on wind and water, causing repeated reinfection and gradual weakening of plants.

Remove infected material and avoid wetting foliage. Grow resistant varieties where possible and rotate crops. Organic sulfur or copper sprays can protect new growth; systemic fungicides are a chemical fallback if rust persists.

Sclerotinia (lettuce drop)

Sclerotinia (lettuce drop) can affect plant health and yields in home gardens. Typical symptoms include slowed growth, discolouration, and reduced productivity, often triggered by weather, nutrition, or cultural conditions.

Start with cultural fixes: rotate crops, improve soil with compost, water consistently, and choose resistant varieties. Organic sprays or amendments can reduce severity; chemical options are a last resort and should be used carefully and in accordance with labels.

Growing Tips

• Sunflower leans in wind; stake taller varieties and sow in blocks for support.
• Sunflower develops small heads in poor soils; prepare ground with compost.
• Sunflower slows growth in cold soil; sow after frosts for rapid growth.