How to Grow Vietnamese Coriander (Rau Răm)

What Rau Răm Is and Where It Grows Well

Rau răm (Persicaria odorata) is a creeping herb from Southeast Asia. The leaves are narrow and pointed, often with a darker mark near the middle, and the young leaves have the sharpest flavor.

It likes the warm, wet conditions many herbs hate. The catch is cold: it is frost-tender and struggles below about 7°C (45°F). Missouri Botanical Garden lists USDA zones 9–11, while ECHO says zones 8–10, so treat the cold edge of either range with caution. In cooler climates, grow it in a pot you can move indoors.

Likes warmth, humidity and steady moisture
Partial shade is the sweet spot
Roots easily from stem cuttings
Grows about 15–45 cm (6–18 in) tall and wide

Starting From Cuttings

Cuttings are the practical way to start rau răm, since it roots at the nodes along its stems. Fresh stems from an Asian grocery or market often work if they are green and not wilted.

Choose 4–5 healthy stems about 10–15 cm long, each with several nodes (the small joints where leaves attach).
Strip the lower leaves so none sit under water, then stand the stems in a glass of room-temperature water in bright, indirect light.
Change the water every few days. Roots usually appear at the nodes within one to two weeks in warm conditions.
Pot the cuttings into soil once the roots are a few centimeters long, and keep the soil damp.

Water gives roots but no nutrients, so do not leave cuttings in the glass for weeks. Whether in water or soil, keep at least one node below the surface, as the Pono plant profile advises.

Rau răm cuttings with long white roots in a glass jar of water on a kitchen counter — Illustration: cuttings with well-developed roots.

Pot, Soil and Feeding

Rau răm creeps outward more than it digs down, so a wide, shallow pot with drainage holes suits it. A pot around 30 cm (12 in) across gives the stems room to sprawl.

Use a loose, rich mix that holds moisture but drains, for example potting soil with some compost and coconut coir. It does not need heavy feeding. A weak liquid fertilizer every month or two is usually enough, and over-feeding tends to give soft, weak growth.

Dark potting mix poured from a bag into a wide, shallow terracotta pot on a wooden table — Illustration: a wide, shallow pot suits rau răm. Make sure yours has drainage holes.

Light and Water

The Pono profile says rau răm tolerates anything from partial sun to full shade, but needs regular water in full sun. A good starting point is a few hours of morning sun and bright, indirect light for the rest of the day.

Moisture is the real story here. Missouri Botanical Garden says full sun is fine where the soil stays reliably wet, so "give it shade" is really advice about water, because shaded pots dry out more slowly.

Keep the soil consistently damp, not soggy. In hot weather a pot can dry out in a day, so check it daily.

Bushy rau răm plant growing in a shady tropical garden bed among ferns and other leafy plants — Illustration: rau răm growing in the ground in partial shade. This guide is about pots, but the shade-and-moisture rule is the same.

Soil moisture matters more than shade. If your pot dries out fast, a hot spot is not the only problem. The water is.

Harvesting and Keeping It Healthy

Snip the longer outer stems with kitchen shears and leave the center to keep growing. Regular harvesting keeps the plant bushy.

The Pono profile lists slugs and fungal disease as possible problems and recommends catching them early, so check the leaves and the soil surface when you water.

Rau răm roots wherever its stems touch moist soil, so a pot keeps it tidy. Plants get leggy with age, and the Pono profile suggests renewing them from cuttings about every two years.

Kitchen scissors cutting a bundle of rau răm stems from a dense, leafy plant in a wooden planter — Illustration: cutting a bundle of outer stems with kitchen shears.

Common Problems and What to Check First

Conditions vary, so treat these as things to check, not fixed rules.

Wilting or scorched leaf edges: check the soil first. If it is dry, soak the pot thoroughly and check it daily during hot weather.
Weak, stretched stems: the plant may be too shaded or too old. Give it brighter light and renew it from fresh cuttings.
Yellowing leaves with wet soil: check the drainage holes and avoid standing water in the saucer.
Holes or slime trails on leaves: look for slugs or caterpillars in the evening and remove them by hand.
Spots or mold on leaves: improve airflow, water the soil rather than the leaves, and remove affected leaves.
Cold weather: bring the pot indoors before temperatures approach 7°C (45°F).

Using Rau Răm in the Kitchen

Rau răm is best used fresh. Long cooking dulls its flavor, so add it at the end or raw. It is commonly used in Vietnamese salads, noodle dishes and soups, and with hột vịt lộn (fertilized duck egg).

Strip the leaves from the tougher stems and chop finely, or tear them over the dish just before serving.

What to Do Next

If you can find a bundle of fresh stems, put a few in a glass of water today. Pot them up once the roots are a few centimeters long, keep the soil damp from day one, and watch how the plant responds to the light where you live.

Sources

Rau răm roots easily. All you need to start is a few stems and a glass of water.