Phlox are fragrant, five-petalled flowers native to North America. Early settlers admired them for their colour and resilience, and they quickly became a staple in cottage gardens. In Australia, phlox are grown for their generous flowering and ability to fill gaps in mixed borders with soft, pastel tones.
Sowing Calendar
Best Months to Plant – Phlox
Climate Zone
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Cool/Mountain
✓
✓
✓
✓
Temperate
✓
✓
✓
✓
Arid
✓
✓
✓
✓
✓
Subtropical
✓
✓
✓
✓
✓
Tropical
✓
✓
✓
✓
✓
✓
✓
Cool/Mountain – Phlox
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
Temperate – Phlox
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
Arid – Phlox
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
✓
Subtropical – Phlox
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
✓
Tropical – Phlox
Method
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Start in trays
✓
✓
✓
✓
✓
✓
✓
Plant out transplants
✓
✓
✓
✓
✓
✓
✓
Direct sow
✓
✓
✓
✓
✓
✓
✓
Where to Plant
Wildflower Areas
Wildflower Areas
• Spaces dedicated to growing mixed flowering species, often from seed
• Mimic natural meadows and support local biodiversity
• Typically low-maintenance and suited to poor or less cultivated soils
• Attract pollinators, beneficial insects, and birds to 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
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
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
High
• Requires consistently moist soil, particularly during warm or dry periods
• Best suited to shallow-rooted or leafy plants such as lettuces, leafy greens, and tropical herbs
• May need daily watering in hot, exposed locations or sandy soils
• Avoid letting soil dry out—wilting may occur quickly if moisture is lost
• Use mulch and drip irrigation to maintain even moisture levels
Fertilisation
Frost
Frost Tolerant
These plants can tolerate light to moderate frosts and may survive through cooler seasons.
Maintenance and Harvesting
Phlox should be deadheaded often to encourage new blooms. Cut back after flowering and divide every few years to maintain healthy growth and prevent mildew.
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.
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.
Growing Tips
• Phlox flowers poorly in shade; plant in full sun with good airflow.
• Phlox declines in drought; water consistently during hot spells.
• Phlox becomes floppy in rich soils; avoid high nitrogen.