Propagating Persicaria odorata (Vietnamese Coriander) from Cuttings

A practical step-by-step guide to propagating aromatic Persicaria odorata from stem cuttings, which root readily at the jointed leaf nodes in water or moist substrate.

Overview

Persicaria odorata, the Vietnamese coriander or rau ram, is an aromatic Asian persicaria of the Polygonaceae family, valued as a culinary herb and grown emersed or semi-aquatic in paludariums. The plant is a relatively compact grower, reaching roughly 15-30 cm in height and spreading up to about 60 cm under favourable conditions. Submerged growth produces pointed olive leaves with reddish margins; it prefers warmth and is sensitive to cold, requiring temperatures above roughly 7 C.

A key structural feature makes this species exceptionally easy to multiply: the stem is jointed at each leaf, and these joints (nodes) readily produce roots when in contact with water or moist soil. This makes cuttings the standard, fastest way to expand a stand.

Propagation Method (Cuttings)

Propagation is by stem cuttings. Semi-ripe cuttings root so readily in water that North American growers recommend simply re-rooting rather than overwintering old plants indoors. The principle is the same whether grown emersed or semi-submerged: take a healthy top section, expose a node, and let that node form new roots before establishing the cutting in substrate.

Step-by-Step

1. Select a vigorous, healthy stem and cut the top 5-10 cm just below a leaf node using clean scissors.
2. Strip the lower leaves to expose one or two bare nodes; these are the sites where new roots will emerge.
3. Place the cutting in water or insert it into moist substrate so the bare node is covered.
4. Keep the cutting warm and brightly lit while roots develop at the node.
5. Once roots are established, plant the rooted cutting into its final emersed or semi-aquatic position; harvestable plants form within roughly two months.

Conditions for Healthy Growth

As a warmth-loving species it does best in warm, well-lit conditions; in the open it prefers full sun and well-drained soil. In aquarium terms it grows well under medium lighting and does not strictly require added CO2, accepting a broad pH range. Keep it above cool thresholds, as it is not frost hardy and suffers below roughly 5-10 C.

Trimming & Maintenance

Trim regularly, on the order of every two weeks, to keep growth dense and to harvest the aromatic tops. Each trimmed top is itself a ready cutting, so routine maintenance and propagation are effectively the same task. Removing tall shoots encourages bushier regrowth from the remaining base.

Common Challenges

The main risk is cold: this species will not tolerate frost and must be kept warm. When transitioning between emersed and submerged forms, expect some adjustment as the plant produces new leaves suited to the new conditions. Otherwise it is undemanding and roots very willingly.