Can you grow Vietnamese coriander hydroponically? Yes. Vietnamese coriander hydroponics is one of the easiest herb projects, because rau ram (Persicaria odorata) roots readily from stem cuttings in water and loves constant moisture. UC Master Gardeners say the easiest start is rooting grocery-store stems in water, and PROSEA reports cuttings start rooting after 3–5 days in warm, humid conditions.
Key takeaway: Vietnamese coriander is a moisture-loving, cilantro-flavored perennial that does not bolt like cilantro. Root 3–4 inch (8–10 cm) tip cuttings in water, move them into DWC, NFT or Kratky, give bright light, and harvest every few weeks. Keep it warm; it is frost-tender.
| Factor | What sources report | Source |
|---|---|---|
| Botanical name | Persicaria odorata (Polygonaceae) | RHS |
| Other names | Rau ram, Vietnamese mint, laksa leaf | UC Master Gardeners |
| Propagation | Stem cuttings with 4–6 internodes, 8–10 cm long | PROSEA |
| Rooting time | Starts after 3–5 days in warm, humid conditions | PROSEA |
| Water | High; prefers moist to wet soil | UC Master Gardeners |
| Harvest | First at about 2 months; then every 3–4 weeks in the US | PROSEA |
What Is Vietnamese Coriander?
Vietnamese coriander is Persicaria odorata, a spreading herbaceous perennial in the knotweed family (Polygonaceae). It is also called rau ram, Vietnamese mint, laksa leaf and phak phai. The RHS describes lance-shaped leaves with a dark purple-brown chevron and a pungent, coriander-like aroma that grows more biting as leaves age.
UC Master Gardeners note it is often grown in warm climates where cilantro would quickly go to seed. Only the leaves are used, raw or cooked, in salads, rice, soups and stews. PROSEA notes the flavor is destroyed by prolonged cooking, so add it at the end.
Why Is Vietnamese Coriander Hydroponics So Easy?
Vietnamese coriander hydroponics is easy because the plant naturally roots at its nodes and thrives in wet ground. UC Master Gardeners list its water needs as high, preferring moist to wet soil, and PROSEA notes it is even planted directly in muddy rice fields in lowland Vietnam. A hydroponic root zone matches those conditions closely.
- Roots in water: UC Master Gardeners root store-bought stems in plain water.
- No bolting: unlike cilantro, it keeps producing leaves.
- Indoor friendly: UC Master Gardeners say it can be grown as an indoor plant.
- Year-round: PROSEA notes greenhouse plants in the US can be harvested year-round.
How Do You Root Vietnamese Coriander Cuttings in Water?
Root Vietnamese coriander by taking tip cuttings with several nodes, stripping the lower leaves and standing them in water. PROSEA describes cuttings with 4–6 internodes, about 8–10 cm (3–4 inches (7.6–10 cm)) long, taken from the tops of mature stems. Under warm, humid conditions roots appear within days and new growth follows in about a week.
- Buy fresh rau ram bunches or cut tips from an existing plant.
- Trim to 3–4 inches (8–10 cm) with 4–6 nodes.
- Remove leaves from the lowest two nodes.
- Stand stems in a jar of clean water in bright, indirect light.
- Change the water every few days.
- Move rooted cuttings into net cups once roots are about 1 inch (2.5 cm) long.
Our humidity dome guide for cuttings helps in dry indoor air.
What Conditions Does Vietnamese Coriander Need?
Give Vietnamese coriander warmth, constant moisture and bright light with some protection from harsh sun. PROSEA says it grows best in partial shade but tolerates full sun with ample moisture. The RHS rates it H1C, meaning it can only grow outdoors in summer in the UK, so keep hydroponic plants indoors through winter.
| Condition | Target | Basis |
|---|---|---|
| Root zone | Constantly moist; well aerated | UC Master Gardeners; PROSEA |
| Light | Bright; partial shade to full sun | PROSEA; RHS |
| Temperature | Warm; frost-tender | RHS hardiness H1C |
| Nutrients | Standard herb solution | General herb practice |
For feeding guidance, see hydroponic nutrients for herbs. PROSEA notes that under dry conditions the stem base becomes woody and leaves yellow, which a hydroponic system avoids.
What Is the Best System for Vietnamese Coriander Hydroponics?
The best system for Vietnamese coriander hydroponics is deep water culture or NFT, since the plant enjoys wet roots. Kratky works for one or two plants. Because stems trail and root at the nodes, give space to spread and trim runners that creep over the edge of net cups.
| System | Fit | Notes |
|---|---|---|
| Deep water culture | Excellent | Wet, oxygenated roots |
| NFT | Excellent | Easy to cut long rows |
| Kratky jar | Good | Top up as level falls |
| Ebb and flow | Fair | Media may dry too often |
How Do You Harvest Vietnamese Coriander?
Harvest Vietnamese coriander by cutting stem tips above a node. PROSEA reports the first harvest when plants are nearly 2 months old, with later harvests every 3–4 weeks in the US. Cutting back stems also rejuvenates the plant. UC Master Gardeners advise using young leaves, which have the best flavor.
In Vietnamese coriander hydroponics, pick in small amounts for home use, and cut whole tops when plants get leggy. Add leaves to dishes at the end of cooking to keep their aroma.
What Problems Affect Vietnamese Coriander Hydroponics?
Problems in Vietnamese coriander hydroponics are usually leggy growth in low light, yellow leaves from cold, and fungal spots in stagnant, humid air. PROSEA notes fungal diseases and slugs sometimes affect rau ram in the US, and more sunlight can reduce damage. Good airflow and bright light prevent most issues.
- Leggy stems: increase light and cut back.
- Yellow leaves: check temperature and nutrient strength.
- Leaf spots: improve airflow and light.
- Woody bases: take fresh cuttings and restart.
How Do You Use Vietnamese Coriander From Your System?
Use Vietnamese coriander raw in salads, spring rolls, noodle soups and rice dishes, or add it at the end of cooking. PROSEA notes prolonged cooking destroys the flavor, and that leaves are often added to brined cabbage in Vietnam. With Vietnamese coriander hydroponics, you can cut small amounts every week. For more herb ideas, see our best herbs for hydroponics.
FAQ About Vietnamese Coriander Hydroponics
Is Vietnamese coriander the same as cilantro?
No. It tastes similar, but it is Persicaria odorata, a different plant family.
Can I start Vietnamese coriander hydroponics from grocery-store rau ram?
Yes. UC Master Gardeners say this is the easiest way to start.
How fast does Vietnamese coriander root in water?
PROSEA reports rooting after 3–5 days in warm, humid conditions.
Does Vietnamese coriander hydroponics need full sun?
No. It grows best in partial shade or bright, filtered light.
Can Vietnamese coriander survive frost?
No. Keep plants indoors in cold weather.
Sources
- UC Master Gardeners of Santa Clara County — Vietnamese coriander
- Royal Horticultural Society — Persicaria odorata
- PROSEA (Plant Resources of South-East Asia) — Persicaria odorata
- Photo credits (Wikimedia Commons, edited with titles): Laksa Leaf by Mokkie (CC BY-SA 3.0)