How to grow native thyme
Overview
Native thyme (Prostanthera incisa) is an aromatic Australian shrub in the mint family, grown for its edible, thyme-like leaves and ornamental purple flowers. It thrives in part shade with well-drained soil and responds well to light pruning after flowering.
Varieties
- Prostanthera incisa 'Edna' — A compact, bushy form with dense foliage and strong thyme-like aroma, ideal for small gardens and containers.
Soil Preparation
Native thyme prefers slightly acidic to neutral soil (pH 5.5–7.0) with excellent drainage. Amend heavy clay with sand or fine gravel to improve drainage. Avoid high-phosphorus fertilisers; use a native-specific blend. Add a thin layer of organic mulch to retain moisture without waterlogging.
Growing Guide
Plant native thyme in a position with morning sun and afternoon shade, in well-drained sandy or loamy soil. Space plants 60–80 cm apart for good airflow. Water deeply but infrequently once established, allowing the soil to dry slightly between waterings. Apply a low-phosphorus native fertiliser in early spring and autumn. Mulch lightly to keep roots cool, but avoid wetting the crown.
Sowing
Sow native thyme seed in spring or early autumn, 2–3 mm deep in a seed-raising mix. Keep moist and warm (18–22°C); germination takes 14–28 days. Transplant seedlings when 5–8 cm tall. Direct sowing is less reliable; use punnets for best results.
Care
Feed with a low-phosphorus native fertiliser in early spring and autumn. Prune lightly after flowering to maintain shape and encourage bushiness. Remove any dead or congested stems to improve airflow. Avoid heavy pruning into old wood as it may not regrow.
Companion Planting
Native thyme pairs well with other low-growing aromatic shrubs like lemon myrtle, rosemary, and prostrate grevillea. Avoid planting near heavy feeders or plants that need high phosphorus, as native thyme is sensitive to phosphorus toxicity.
Common Pests & Risks
Scale insects and root rot can affect native thyme in humid or poorly drained conditions. Control scale with a horticultural oil spray in early spring. Improve drainage and avoid overwatering to prevent root disease. Monitor for fungal leaf spots in wet weather and remove affected foliage promptly.
Harvesting
Harvest native thyme leaves from late spring through autumn, picking sprigs as needed for fresh use. For best flavour, pick leaves in the morning after dew has dried. Regular light harvesting encourages bushier growth and prevents the plant from becoming leggy.
In the Kitchen
Use fresh native thyme leaves as a substitute for common thyme in savoury dishes, especially with lamb, chicken, or roasted vegetables. The leaves have a milder, slightly citrusy flavour. Store fresh sprigs in a sealed bag in the fridge for up to a week, or dry for longer storage.
Troubleshooting
Yellow leaves: overwatering or poor drainage; reduce watering and improve soil. Brown leaf edges: too much sun or heat stress; move to part shade. Leggy growth: insufficient light or lack of pruning; move to brighter spot and prune after flowering. Stunted growth: phosphorus toxicity; use native fertiliser only. Leaf drop: root rot from wet soil; check drainage and avoid overwatering.