Vietnamese Coriander

Vietnamese coriander is the herb that appears on every Vietnamese restaurant table in a pile alongside mint and bean sprouts, the one with long pointed leaves with distinctive dark chevron markings, and the one most non-Vietnamese diners can’t identify by name. It’s called rau răm in Vietnamese, and it’s the defining herbal note in Vietnamese cold dishes, green papaya salad, and the herb plates that accompany pho, bún bò Huế, and other soups.

The flavor is hard to describe precisely: it has cilantro’s aromatic pungency but is sharper, more peppery, with a finish that’s almost minty. It doesn’t taste like cilantro or like mint, though it suggests both. At Southeast Asian markets it sells for $8-15/lb. Outside areas with Vietnamese or Cambodian communities, it’s essentially unavailable commercially.

The plant is a tropical perennial that, unlike cilantro, does not bolt in heat. It grows through summer, roots at nodes like mint, and takes over a container or bed happily if not contained.

What it actually is

Persicaria odorata is in the buckwheat family (Polygonaceae), native to Southeast Asia. It has no botanical relationship to cilantro (Coriandrum sativum) - the similarity is purely flavor-based. The plant is more closely related to water pepper and knotweed than to any culinary herb in the carrot family.

The stems are reddish-tinged, jointed (like all Persicaria species), and root readily at nodes when they touch moist soil. The leaves are 2-3 inches long with a pointed tip and often show a distinctive brown or maroon chevron pattern in the center of the upper leaf surface - a useful identification feature.

In frost-free climates it’s a perennial ground cover that spreads slowly. In zones 5-8, it’s grown as a warm-season annual or overwintered as a container plant. It withstands more cold than ginger or lemongrass but still dies at sustained frost.

Also called: rau răm (Vietnamese), laksa leaf (Malaysian/Singaporean), daun kesum (Indonesian/Malay), hot mint (common English), Cambodian mint, Vietnamese mint.

The ROI case

Vietnamese coriander’s value is access. There’s no commercial equivalent outside Vietnamese markets. A single container planting produces enough for regular use through the warm months.

Planting	Plants	Seasonal yield	Value @$10/lb	Seed cost	Net
3 plants (container)	3	0.25-0.5 lb	$2.50-5.00	$1.50*	$1.00-3.50
Ground patch (4 sq ft)	6-8	0.5-1.0 lb	$5.00-10.00	$2.99	$2.01-7.01

*Estimated; often propagated from cuttings taken from a grocery store purchase.

Propagation from grocery store: fresh stems purchased at a Vietnamese market root easily in water within 1-2 weeks. This is the most common and cheapest way to obtain the plant.

Growing requirements

Climate: tropical perennial; frost-tender. Outdoor growing season is late spring through first frost in zones 5-8. In zones 9-11, grows year-round. Minimum temperature for outdoor culture: 45°F.

Starting: Vietnamese coriander is almost always propagated from cuttings rather than seed (seeds have low germination rates and are rarely sold commercially). Take 4-6 inch stem cuttings from any plant; strip the lower leaves; place in a glass of water. Roots develop in 7-14 days at room temperature. Transfer to soil once roots are 1-2 inches long. Plants purchased as starts from nurseries (rare outside specialty plant sellers) can be divided at the root.

Soil: adaptable; tolerates moist, even slightly boggy conditions - the plant grows naturally along stream banks in tropical Asia. In containers, use a moisture-retentive mix. Does not tolerate completely dry soil.

Spreading: like mint, Vietnamese coriander spreads by rooting at nodes. In ground plantings, contain it with buried edging or grow in containers to prevent it from taking over. In containers, it trails attractively over the edges.

Overwintering: bring container plants indoors before first frost. Keep in a warm (60°F+), bright location. Growth slows in low light but the plant survives. Alternatively, take cuttings in early fall and root indoors; discard the mother plant; grow on the rooted cuttings through winter.

Harvest: cut stem tips (last 4-6 inches with leaves) regularly. The plant branches at each cut, producing more tips. Harvest every 1-2 weeks during peak growth.

What goes wrong

Cold damage: leaves turn black and mushy below 40°F. The stems often survive light frost if covered, but don’t push the frost tolerance. Bring containers in early.

Leggy plants: results from insufficient light or not harvesting regularly enough. The plant stretches toward light and loses its compact form. Move to brighter conditions; cut back hard to encourage bushy regrowth.

Rooting failures: cuttings in water are almost foolproof, but failure happens if water isn’t changed regularly (stagnant water grows bacteria) or if stems are old and woody rather than young and green. Use new tip growth for cuttings.

Strong flavor overwhelming dishes: rau răm is potent. In dishes where it’s used as a garnish (pho herb plate), a few leaves per serving is appropriate. Cooked into a dish, it mellows considerably.

Harvest and use

Harvest the tender growing tips - the last 4-6 inches of each stem with the young leaves. The chevron-patterned leaves are the ones typically served whole as a garnish; the smaller tip leaves are the most tender for mixed preparations.

Fresh only: Vietnamese coriander doesn’t dry well - the flavor profile collapses. Use fresh, or freeze in oil for cooking applications. This is another reason growing your own matters: the herb exists for home cooks only as a fresh ingredient.

Core preparations:

• Pho herb plate: the classic context. Fresh rau răm leaves placed alongside bean sprouts, Thai basil, fresh chilies, and lime wedges on the herb plate that accompanies pho. Diners add leaves to the hot broth at the table; they wilt slightly and release their peppery-herbal aroma into the soup.

• Vietnamese green papaya salad (gỏi đu đủ): shredded green papaya dressed with fish sauce, lime, chili, and herbs including rau răm. The herbal sharpness cuts through the dressing and complements the papaya’s neutral crunch.

• Vietnamese duck salad: the classic use of rau răm in Vietnamese home cooking. Cold duck or chicken, shredded, with glass noodles, shallot, and a large quantity of rau răm leaves. The herb is not a garnish here; it’s a primary ingredient by volume.

• Laksa (Malaysian/Singaporean): in some regional versions of the spiced coconut noodle soup, laksa leaf (daun kesum) is simmered in the broth and added fresh as garnish. It’s what gives Sarawak laksa and Assam laksa their specific herbal character.

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Related reading: Culantro - tropical cilantro relative with similar heat tolerance; Thai Basil - fellow Southeast Asian fresh herb