How to grow peppermint
Overview
Peppermint (Mentha x piperita) is a sterile hybrid grown for its strong, cool-flavoured leaves, used in teas, cooking, and fragrance. It spreads aggressively by underground runners and is best contained in a pot or isolated bed to prevent taking over the garden.
Varieties
- Mentha x piperita 'Black Mitcham' — The classic English peppermint with high oil content and strong flavour, widely grown in Australia for tea and distilling.
- Mentha x piperita 'Chocolate' — A popular Australian cultivar with a hint of chocolate scent; leaves are dark green with purple undersides.
- Mentha x piperita 'Lime' — A citrus-scented peppermint that adds a zesty note to drinks and desserts; grows well in subtropical gardens.
Soil Preparation
Peppermint prefers rich, loamy soil with a pH of 6.0–7.0; add well-rotted compost or aged manure before planting. Ensure the soil holds moisture but drains freely—heavy clay needs gypsum or raised beds to avoid waterlogging. In pots, use a premium potting mix with added water-retention crystals.
Growing Guide
Plant peppermint in a damp, part-shaded spot with morning sun and afternoon shade, or in a pot that can be moved. Space divisions or seedlings 30–40 cm apart; for in-ground beds, sink a bottomless bucket or use a solid barrier to limit root spread. Keep soil consistently moist but not waterlogged—mulch heavily with straw or bark to retain moisture. In hot zones, position near a tap or damp area to make watering easy. Divide every 2–3 years to keep plants vigorous and prevent root congestion.
Care
Feed every 4–6 weeks during active growth with a balanced liquid fertiliser (e.g., seaweed or fish emulsion) at half strength. Pinch stem tips weekly to encourage branching and delay flowering; cut back to 5 cm in autumn to tidy the plant. Divide clumps every 2–3 years to maintain vigour and prevent the centre from dying out.
Companion Planting
Peppermint repels ants, aphids, and some flea beetles, making it a useful companion near brassicas (cabbage, broccoli) and tomatoes. Avoid planting near parsley, chamomile, or other mints to prevent cross-contamination of flavour and to reduce competition for space.
Common Pests & Risks
Rust (orange pustules on leaf undersides) is common in humid, crowded conditions—improve air flow and remove infected leaves. Aphids and two-spotted mites can be hosed off or treated with neem oil; avoid overhead watering to reduce rust. Mint root rot (Phytophthora) occurs in waterlogged soil—ensure good drainage and don't overwater.
Harvesting
Harvest leaves from spring through autumn, picking before the plant flowers for the best flavour. Cut whole stems at 10–15 cm above soil level, leaving lower leaves to regrow; regular harvesting keeps plants bushy and prevents flowering. For the strongest oil content, pick in the morning after dew has dried.
In the Kitchen
Use fresh leaves in teas, salads, and sauces; they can be frozen in ice cubes or dried for later use. For the best flavour, add leaves at the end of cooking to preserve the volatile oils. Peppermint pairs well with lamb, peas, and chocolate.
Troubleshooting
Yellowing leaves: often caused by overwatering or poor drainage—check for root rot and reduce watering. Brown leaf edges: usually from underwatering or hot, dry winds—increase mulch and water more frequently. Stunted growth: may indicate root-bound pots or congested clumps—divide and repot. Rust on leaves: remove infected foliage and improve air circulation; avoid overhead watering. Leaves losing flavour: occurs after flowering—cut back hard and harvest before flowers appear.