Zinnias originated in Mexico and were once considered wild and unruly. With breeding, they became favourites for their bold colours, ease of care, and butterfly appeal. In Australia, zinnias flourish in hot summers, bringing a carnival of colour to borders and cut flower gardens.
Sowing Calendar
Best Months to Plant – Zinnia
Climate Zone
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Cool/Mountain
✓
✓
✓
✓
Temperate
✓
✓
✓
✓
Arid
✓
✓
✓
✓
✓
Subtropical
✓
✓
✓
✓
✓
Tropical
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
✓
Cool/Mountain – Zinnia
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
Temperate – Zinnia
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
Arid – Zinnia
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
✓
Subtropical – Zinnia
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
✓
Tropical – Zinnia
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
Hanging Baskets & Vertical Planters
Hanging Baskets & Vertical Planters
• Containers suspended above ground or mounted vertically to save space
• Ideal for trailing or compact plants such as strawberries, herbs, or flowers
• Enhance airflow and accessibility for tending
• Require more frequent watering due to increased exposure
In-Ground Garden Beds
In-Ground Garden Beds
• Traditional garden beds dug directly into the soil
• Suitable for deep-rooted crops and long-term plantings
• Offers natural soil ecology and drainage benefits
• Requires proper soil preparation and weed management
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
Low
• Suitable for drought-tolerant or Mediterranean-style plants
• Needs watering only during extended dry periods or heatwaves
• Prefers deep but infrequent watering to encourage strong root growth
• Ideal for well-drained soils and low-maintenance garden beds
• Mulching helps retain moisture and reduce watering even further
Fertilisation
Frost
Frost Tolerant
These plants can tolerate light to moderate frosts and may survive through cooler seasons.
Maintenance and Harvesting
Zinnias are low-maintenance but benefit from deadheading. Water at the base to avoid fungal issues and provide good air circulation to reduce mildew risk.
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.
Leaf spot
Leaf spot describes several fungal or bacterial diseases that create dark, often round lesions on foliage—sometimes with yellow halos. Severe infections cause premature leaf drop and reduced vigour, especially during warm, wet spells or when leaves stay damp.
Reduce spread by removing infected leaves, watering at the base, and spacing plants for airflow. Mulch to limit soil splash and rotate crops. Organic preventatives include copper and sulfur sprays applied early. If disease escalates, registered fungicides offer a chemical backup.
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.
Two-spotted spider mites
Two‑spotted spider mites are tiny sap‑suckers that stipple leaves, causing a speckled, yellow look and fine webbing—worst in hot, dry conditions. Unchecked, plants can defoliate.
Increase humidity around plants, hose undersides of leaves, and release or encourage predatory mites. Neem and horticultural oils suppress populations organically. Miticides exist for heavy outbreaks; rotate actives to reduce resistance.
Early blight (Alternaria)
Early blight (Alternaria) 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
• Zinnia stems become weak in shade; plant in full sun.
• Zinnia flowers are smaller in poor, dry soils; improve soil and water evenly.
• Zinnia petals spot after rain or overhead watering; water at the base.
