Repotting guide

When & how to repot Vietnamese Coriander (Persicaria odorata)

Also called Vietnamese coriander, Vietnamese mint, rau ram, Cambodian mint, laksa leaf, Asian mint.

More about vietnamese coriander

About Vietnamese Coriander

Persicaria odorata · also called Vietnamese coriander, Vietnamese mint · herb

Vietnamese coriander (Persicaria odorata), or rau ram, is a heat-loving Southeast Asian culinary herb with a peppery, cilantro-like flavour that does not bolt in summer heat. Give it bright light, constantly moist soil and warmth. Not listed by the ASPCA, but related buckwheat-family plants are toxic, so verify with your vet.

Mature size: Roughly 15-45 cm (6-18 in) tall and a similar or wider spread; stems trail and root as they spread, so plants stay low and bushy rather than tall.

Watch for — Leaf scorch in intense sun: In very hot climates, harsh midday sun combined with any moisture stress can dry and brown the leaf edges. Provide afternoon shade and keep the root zone reliably moist.

How to tell vietnamese coriander needs repotting

Repotting on a calendar is less reliable than reading the plant. For vietnamese coriander, watch for these signs:

Roots circling the bottom of the module or pot, or poking out of the drainage holes.
The seedling dries out within a day and growth has visibly stalled.
Roots are white and matted in a tight spiral when you tip the plant out.
It has outgrown its current container for the stage of the season — pot vietnamese coriander on before it becomes hard root-bound.

For the underlying biology of a pot-bound root system and why it stalls a plant, see our guide to spotting and fixing a root-bound plant.

How often to repot vietnamese coriander

Pot on seedlings as they grow; not a perennial repot. Vietnamese Corianderis grown for one season, so the question is really “how often to pot on” — keep moving it up before the roots circle. Sprawling, mat-forming evergreen perennial herb with reddish jointed stems that creep along the ground and root freely at the nodes wherever they touch soil. Grown as a tender perennial in frost-free zones and as an annual or overwintered container plant in colder climates..

What size pot to step vietnamese coriander up to

Pot vietnamese coriander on gradually — a seedling jumped straight into a huge pot sits in cold, wet, airless soil and stalls. Step up one or two sizes at a time as the roots fill each container, finishing in a large final pot or the ground. The aim is roots that never circle and never check.

Not sure of the exact diameter? Our pot size calculator takes the current pot and root spread and tells you the right next size — it deliberately recommends a single step up, never a big jump.

The best time of year to repot vietnamese coriander

Pot vietnamese coriander on through the active growing season, whenever roots fill the current container — there is no single date, just "before it becomes root-bound". Avoid potting on during a cold snap.

Step-by-step: repotting vietnamese coriander

Pot on before it is root-bound. Check vietnamese coriander regularly; move it up as soon as roots reach the edge of the cell or pot, not after they have circled.
Step up one or two sizes. Choose the next container up — not a giant one. Cold, wet, unused soil around a small root system stalls seedlings.
Knock it out gently. Support the stem, tip the pot, and ease the rootball out without breaking it. A little teasing of circled roots at the base is fine.
Pot into rich mix. Set it into fresh rich, moisture-retentive but well-draining potting mix or garden soil at the same depth (tomatoes are the exception — they can go deeper to root along the stem).
Water in and grow on. Water well, keep it in good light, and resume feeding once it is established and growing again.

Aftercare

Water vietnamese coriander in well and keep it in bright light; a freshly potted-on seedling can wilt for a day while roots settle, so do not overcompensate by drowning it. Do not fertilise for about 1 week — fresh mix already carries nutrients and feeding freshly disturbed roots scorches them.

The right soil mix for vietnamese coriander

Vietnamese Coriander wants rich, moisture-retentive but well-draining potting mix or garden soil. Prefers fertile soil high in organic matter that holds moisture. Tolerates sandy, loamy or clay soils across mildly acidic to mildly alkaline pH. Enrich garden beds with compost; for pots use a quality mix amended with extra organic matter to retain moisture while still draining. Always use fresh mix when you repot — reusing old, broken-down soil reintroduces the compaction and poor drainage you are repotting to fix.

Repotting vietnamese coriander — frequently asked questions

How often should you repot vietnamese coriander?

Pot on seedlings as they grow; not a perennial repot for vietnamese coriander. Vietnamese Coriander is a seasonal crop, so you pot it on as a growing plant rather than repotting a perennial. Step seedlings up gradually into rich, moisture-retentive but well-draining potting mix or garden soil so the roots never circle the cell, ending in a large final container. A root-bound transplant stalls and never fully recovers.

What size pot does vietnamese coriander need?

When is the best time of year to repot vietnamese coriander?

Can you put vietnamese coriander straight into a much bigger pot?

No. Even a fast-growing vietnamese coriander should only go up one pot size at a time. A vastly oversized pot holds a reservoir of wet soil the roots cannot reach, which stays cold and soggy and rots the roots — the opposite of what you wanted.

Should you fertilise vietnamese coriander after repotting?

Not immediately. Wait about 1 week after repotting vietnamese coriander. Fresh mix already contains nutrients, and feeding freshly cut or disturbed roots burns them. Resume your normal feeding routine once you see new growth.