How to grow native river mint
Overview
Native river mint (Mentha australis) is a sprawling, moisture-loving shrub with a strong mint aroma. It is grown for its edible leaves and as a groundcover in damp, part-shaded areas. Keep it contained or it will spread via runners.
Soil Preparation
Prefers a slightly acidic to neutral pH (6.0–7.0) in rich, loamy soil with high organic matter. Before planting, dig in well-rotted compost or aged manure. Ensure soil stays moist but not waterlogged—add sand or grit if drainage is poor.
Growing Guide
Plant in part-shade with morning sun and afternoon relief. Space 40–50 cm apart in rich, consistently moist soil. Dig a hole twice the pot width, backfill with compost, and water in well. Mulch heavily to retain moisture and suppress weeds. Propagate by dividing clumps in early spring or by rooting stem cuttings in water.
Care
Feed with a balanced liquid fertiliser (e.g., seaweed or fish emulsion) every 4–6 weeks during active growth. Prune back leggy stems in early spring to encourage dense regrowth. Divide clumps every 2–3 years to maintain vigour and prevent overcrowding.
Companion Planting
Grows well with lemon balm, parsley, and watercress in damp beds. Avoid planting near lavender, rosemary, or other dry-loving herbs as they compete poorly for moisture. Keep it away from invasive grasses that will smother its runners.
Common Pests & Risks
Rust (orange pustules on leaf undersides) appears in humid, crowded conditions—improve air flow and remove affected leaves. Aphids cluster on new growth; blast off with water or apply a dilute neem oil spray. Avoid overhead watering to reduce rust.
Harvesting
Harvest leafy stems from late spring through autumn, cutting just above a leaf node to encourage bushy regrowth. Pick regularly—every 2–3 weeks—to prevent flowering and keep leaves tender. Use fresh or dry for later use.
In the Kitchen
Use fresh leaves in teas, salads, or as a garnish for lamb and peas. Dry leaves for a milder mint tea. Store fresh stems in a damp paper towel in the fridge for up to a week, or freeze chopped leaves in ice cubes.
Troubleshooting
Yellow leaves: overwatering or poor drainage—reduce water and check roots. Brown leaf edges: underwatering or salt burn—flush soil and water more consistently. Leggy growth: too much shade—move to brighter part-shade. Rust: poor air flow—space plants wider and remove infected leaves. Stunted growth: nutrient deficiency—apply balanced liquid feed.