How to grow vietnamese mint in Australia
Also known as: Vietnamese Coriander, Hot Mint, Laksa Leaf, Rau Răm
Vietnamese mint is one of those herbs that every Australian gardener who cooks Southeast Asian food eventually grows — and then wonders why they waited so long. It's not a true mint at all (it belongs to the knotweed family) but it shares that vigorous, spreading habit. Unlike common mint, it thrives in summer heat, handles the wet tropics, and doesn't mind humidity. The leaves have a sharp, peppery, almost citrusy flavour — essential in Vietnamese fresh rolls, laksa, Malaysian soups, and as a garnish for pho. It's sold under many names at garden centres: rau răm, laksa leaf, hot mint, Vietnamese coriander.
When to plant
Vietnamese mint is planted from cuttings or runners year-round in warm climates, and from spring through summer in cooler zones. It goes dormant in cold winters.
One of the best climates for Vietnamese mint — grows almost like a weed in tropical wet season conditions. Plant any time. It will need occasional trimming to stay productive rather than flowering and going woody. In Darwin this is a near year-round harvest herb.
Excellent conditions. Plant spring through summer for best establishment. In SE QLD it grows enthusiastically from September through April. Light frost events in the Hinterland can knock it back but it regrows from the roots in spring.
Plant October through February. In Sydney's warmer western suburbs it performs well all summer. In coastal Sydney and Perth it's reliable through the warm months. Goes dormant in winter but returns from the roots reliably each spring.
Plant October–November. Gets cut back to the ground by Melbourne winters but regrows each spring — treat it as a semi-perennial in Melbourne. Give it a warm, sheltered spot and a pot will allow you to bring it under cover. Much harder to keep through Ballarat or Bendigo winters.
Container growing is the right approach. Bring the pot under cover or inside for winter. It will die back completely but regrow when warmth returns in spring.
Grows well in the warm months if given consistent moisture and some afternoon shade from the harshest heat. Struggles in the combination of intense heat and low humidity without irrigation. A pot near a water source works well.
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Vietnamese mint is almost never started from seed — it rarely flowers, and when it does the seeds are not reliably fertile. Always buy a pot from a garden centre or take cuttings from an established plant. A 10cm cutting stuck in moist potting mix or placed in a glass of water will root within a week in warm weather.
Spacing: 30cm apart. It spreads via runners so give it room, or confine it in a pot.
Depth: Plant so the root system is covered — about 5cm of stem below the soil surface is ideal for cuttings.
Soil: Moist, well-draining soil rich in organic matter. Unlike Mediterranean herbs, Vietnamese mint doesn't want dry conditions. It's more tolerant of wet soil than most herbs.
Containment: Like true mint, it spreads via runners. If planting in a garden bed, sink a root barrier or an old pot with the bottom cut off to contain it. A pot on a paved surface prevents escape entirely.
Pots, raised beds, or in-ground?
Pots are the most practical way to grow Vietnamese mint for most Australian gardeners — they contain the spreading habit and can be moved to a sheltered spot in winter. A 30cm pot gives a productive plant. Water frequently — pots dry out fast in summer heat.
Raised beds work well with a buried barrier to prevent runner escape into the rest of the bed. Give it a corner or edge position.
In-ground in dedicated herb garden areas is fine, but Vietnamese mint will attempt to colonise surrounding space. Plant in a contained section or accept that you'll need to trim back runners regularly. In tropical and subtropical gardens where it's always in growth, this is manageable.
Sunlight & water
Vietnamese mint handles more shade than most herbs — 4–6 hours of sun is enough for good production, and afternoon shade is appreciated in hot climates. In full tropical or summer sun the leaves can scorch at the tips.
Water consistently — Vietnamese mint does not tolerate prolonged dry periods. It's accustomed to the moist, humid environments of Southeast Asia. In pots, daily watering may be needed in summer. In the ground, a good layer of mulch helps maintain the consistent moisture it prefers.
Pinch out flower spikes as they appear to keep the plant producing fresh, flavourful leaves. Once allowed to flower, plants put energy into seeds (rarely viable) and the leaves become smaller and less flavourful.
When and how to harvest
Harvest young tip growth — the top 10–15cm of stems — by pinching or snipping. This encourages bushy growth and prevents the plant from getting leggy. You can harvest heavily in warm weather; the plant will regrow quickly.
For best flavour, use leaves fresh. Vietnamese mint loses its sharp, peppery character when cooked — add it at the end of cooking or use it raw as a garnish. It's best in cold dishes: rice paper rolls, cold noodle salads, as a garnish for pho, in laksa, and in fresh spring rolls.
Don't let the plant flower if you can help it — flowering signals the end of the productive season and flavour drops off.
Common problems
Root rot is the most common problem — Vietnamese mint needs moisture but not waterlogging. In heavy clay soils or pots without drainage holes, the roots rot rapidly. Ensure free drainage.
Tip burn in hot, dry conditions shows as browning at the leaf tips. Increase watering and provide afternoon shade. This is common in dry, inland Australian summers.
Legginess — the plant stretches and becomes woody with fewer leaves if not regularly harvested. Hard prune in early spring (cut back to 10cm above the ground) to rejuvenate the plant.
Winter dieback — normal in cool temperate and cool/cold zones. Don't remove the plant if it dies back; it will regrow from the roots in spring. Mark the pot clearly so you don't accidentally discard it.
Companion planting
Vietnamese mint integrates well into an Asian herb garden alongside Thai basil, coriander, lemongrass, chilli, and ginger — plants that share its moisture preferences and warm-season growing window. It's a natural companion to eggplant, which is used in many of the same cuisines.
It doesn't have well-documented allelopathic effects, but its runner-spreading habit means it competes for space rather than nutrients. Keep it away from delicate or slow-growing herbs it might overwhelm. Unlike true mint, it doesn't have a reputation for suppressing neighbours through chemical means.
Australian varieties
Persicaria odorata (standard Vietnamese mint) — the common form sold in Australian garden centres and Vietnamese/Asian grocery stores. Green leaves, sometimes with a dark blotch in the centre. This is what you want.
Red-stemmed Vietnamese mint — a form with reddish stem colouration. Flavour is essentially identical. Sometimes sold as an ornamental variant. Growing requirements are the same.
A note on labelling: plants sold as "laksa leaf", "rau răm", "hot mint", and "Vietnamese coriander" are all the same species. Don't be confused by the different names — check the leaf shape (elongated, slightly pointed, pale underside with a distinctive peppery scent when rubbed).
