Rau Ram

The Vietnamese name for laksa leaf, essential in pho, spring rolls, and laksa soup throughout Southeast Asia. This sprawling herb roots readily at stem nodes and can be grown in shallow water or very moist soil. Pinch stem tips regularly to encourage branching and prevent the plant from becoming leggy and sparse.

Rau ram rarely flowers or sets seed outside the tropics and is almost exclusively propagated vegetatively. Take stem cuttings 4 to 6 inches long from healthy plants, remove lower leaves, and place in a glass of water. Roots develop within 5 to 10 days in warm conditions. Once roots are 1 to 2 inches long, transplant to moist potting soil or directly into the garden. Cuttings can also be rooted directly in moist soil by burying 2 to 3 leaf nodes. New plants from cuttings establish quickly and can be harvested within 3 to 4 weeks.

Rau ram, also known as Vietnamese coriander or laksa leaf, is a tropical herb that thrives in warm, humid conditions with consistent moisture. Unlike cilantro, which bolts quickly in heat, rau ram actually prefers hot weather and maintains its flavor throughout the hottest months, making it an ideal summer substitute. Plant in partial shade to full sun in rich, moist soil with a pH of 6.0 to 7.0.

This trailing herb roots easily at stem nodes and spreads vigorously in favorable conditions. Start from cuttings placed in water until roots develop, then transplant to moist soil or grow directly in shallow water like a semi-aquatic plant. Container culture works excellently; use a pot without drainage holes or place a standard pot in a saucer kept full of water.

Pinch stem tips regularly to encourage bushy, branching growth and prevent the plant from becoming leggy. In tropical zones, rau ram is perennial and may become aggressive. In temperate climates, bring containers indoors before the first frost and place in a bright window. Reduce watering slightly in winter but never allow the soil to dry completely. Provide high humidity indoors with a pebble tray or regular misting.

Rau ram grows well alongside other Southeast Asian herbs including Thai basil, lemongrass, and galangal in a tropical herb garden. Its moisture-loving nature makes it a good companion for mint, which shares similar water needs. Grow near water features or in bog gardens alongside watercress and taro. Keep away from drought-tolerant Mediterranean herbs that require very different conditions.

Rau ram thrives in rich, moist to wet soil with a pH of 6.0 to 7.0. It can be grown in standard potting soil kept consistently moist or in shallow water like a bog plant. Add compost generously to garden soil before planting. Feed every 2 to 3 weeks with a balanced liquid fertilizer during active growth. In container culture, use a rich organic potting mix and feed more frequently since nutrients leach with constant watering. Reduce feeding in winter when growth slows.

Ideal Temperature

Hardiness Zone Compatibility

Harvest rau ram leaves and tender stem tips throughout the growing season once plants are well established with multiple branches. Pinch or cut stem tips 2 to 3 inches long, which encourages branching and new growth. The leaves have the strongest flavor when used fresh; harvest just before use for best results. Older leaves near the base have a stronger, more peppery flavor, while young tip leaves are milder and more aromatic. The characteristic V-shaped chevron marking on the leaves indicates healthy, vigorous growth.

Storage & Preservation

Fresh rau ram stores in the refrigerator for up to a week when wrapped in damp paper towels in a sealed container. Alternatively, stand stems in a glass of water in the refrigerator, changing water every 2 days. The herb does not dry well, as it loses most of its distinctive flavor when dried. Freezing is the best preservation method: chop leaves and freeze in ice cube trays with a little water or oil. Frozen rau ram retains good flavor for 3 to 6 months and works well in cooked dishes.

Troubleshooting Common Problems

The most common problem is drying out, which causes leaf wilting and tip burn almost immediately. This plant cannot tolerate drought even briefly. In temperate climates, cold is the main threat; any frost will kill the plant. Indoor plants often suffer from low humidity and insufficient light in winter, becoming leggy and sparse. Spider mites can infest indoor specimens in dry conditions. Overly vigorous spreading in tropical regions may require containment.

Growing Tips

1. Start rau ram from stem cuttings rather than seed. Seeds are rarely available and germination is unreliable. Fresh cuttings from an Asian grocery store or a friend's garden root readily in water within 5-7 days. Look for stems with healthy nodes and remove lower leaves before rooting.
2. Provide consistently moist soil — rau ram is a semi-aquatic plant that naturally grows along stream banks and in wet areas. It thrives in conditions that would rot most herbs. Standing water in saucers beneath pots is actually beneficial for this moisture-loving plant, unlike nearly all other herbs.
3. Grow in partial shade to full sun. In hot climates (zones 9-12), afternoon shade prevents leaf scorch and maintains tenderer, more flavorful foliage. In cooler climates, full sun is preferred to maximize growth rate and aromatic compound production during the shorter growing season.
4. Use rich, moisture-retentive soil amended with plenty of compost. Rau ram is a heavy feeder that benefits from fertile soil and regular applications of balanced liquid fertilizer every 2-3 weeks during the active growing season. Soil that drains too quickly causes stress.
5. Pinch off flower spikes as soon as they appear at the stem tips. Flowering diverts energy from leaf production and can change the flavor balance of the foliage. Regular tip harvesting naturally delays flowering and promotes bushier, more productive growth.
6. Contain the plant's spread in garden beds by growing in sunken pots, raised beds with barriers, or standalone containers. Rau ram roots at every node that contacts moist soil and can colonize large areas in a single season if left unchecked. A 30 cm deep root barrier is usually sufficient.
7. Overwinter rau ram indoors in zones 8 and below, since it has no frost tolerance. Pot up a section of the outdoor plant in September, cut it back to 15 cm, and place on a bright windowsill or under grow lights. It will continue producing modest harvests through winter with reduced watering.
8. Harvest by cutting stem tips back to a leaf node, taking 10-15 cm lengths. This encourages branching at the cut point, resulting in two or more new shoots for each one harvested. Avoid cutting into old woody stems at the base, which regenerate more slowly.
9. Mist indoor plants regularly or place pots on humidity trays, as rau ram evolved in humid tropical conditions and suffers in the dry air typical of heated homes during winter. Grouping tropical herbs together and running a small humidifier nearby helps maintain adequate humidity levels.
10. Watch for slugs and snails outdoors, as they are strongly attracted to the lush, tender foliage. Copper tape barriers around containers and organic slug pellets around garden plantings are effective controls. Indoors, inspect for aphids and whitefly, treating early with insecticidal soap.