Vietnamese coriander
Persicaria odorata
Unrelated to coriander and to mint despite both names, and the one herb here that solves a real problem: it tastes close enough to coriander to replace it and does not bolt, because it is a spreading tender perennial rather than an annual that runs to seed. The catch is that a frost kills it outright.
- Position
- Partial shade or Full sun
- Water
- high demand
- Drainage
- Moisture-retentive, Tolerates wet ground
- Grows to
- 25–40 cm × 40–60 cm
- Hardiness
- H1C
- Harvest
- May to October
- Difficulty
- Some care needed
August
Harvest · Take cuttings
Vietnamese coriander’s year
Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.
| Activity | J | F | M | A | M | J | J | A | S | O | N | D |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Harvest | May. | June. | July. | August. | September. | October. | ||||||
| Take cuttings | April. | May. | June. | July. | August. | |||||||
| Protect | October. | November. |
Timing that travels
The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.
What kind of herb this is
Herbs are a kitchen grouping rather than a botanical one, and the plants in it want opposite things. This is the one distinction that decides how to treat it.
Tropical, frost-tender herb
Growing regimesource
Sourced guidancehigh confidence
- Royal Horticultural Society: Vietnamese coriander — growing
Checked 2026-08-13
Frost kills it outright. It has to come inside for winter or be treated as an annual, and the indoor months are survival rather than growth.
Treated the same way: curry leaf, lemon verbena, lemongrass. The herb bed, split by regime
- Indoors
- Grows indoors all year
Where the indoor assessment comes from
- IndoorsSourced guidancemoderate confidence
- Royal Horticultural Society: Vietnamese coriander — growing indoors
Checked 2026-08-13
Almost any herb will sit on a windowsill in July. This is about whether it is still there in March, which is the part a pot on a supermarket shelf does not tell you.
What happens when it flowers
On a herb this is rarely a problem and rarely nothing. It is the point at which the plant stops being what you grew it for — by a lot, a little, or not at all.
source
Sourced guidancehigh confidence
- Royal Horticultural Society: Vietnamese coriander — harvesting
Checked 2026-08-13
Nothing to do about it. Flowering does not change what vietnamese coriander is worth picking, so there is no reason to prevent it.
Conditions it needs
- Light
- Partial shade, Full sun
- Frost
- Frost tender
- Hardiness rating
- H1c (RHS)
- Grows best at
- 18–30 °C
- Soil
- Loam, Peat-free compost, Silt
- Soil pH
- 5.5–7
- Drainage
- Moisture-retentive, Tolerates wet ground
- Water needs
- high
- Drought
- poor tolerance
- Waterlogging
- good tolerance
- Heat
- good tolerance
- Wind and exposure
- poor tolerance
Where these figures come from
- LightSourced guidancemoderate confidence
- Royal Horticultural Society: Vietnamese coriander — position
Checked 2026-08-13
- FrostSourced guidancehigh confidence
- Royal Horticultural Society: Vietnamese coriander — hardiness
Checked 2026-08-13
- Hardiness ratingSourced guidancemoderate confidence
- Royal Horticultural Society: RHS hardiness ratings
Checked 2026-08-13
- Grows best atSourced guidancemoderate confidence
- Royal Horticultural Society: Vietnamese coriander — temperature
Checked 2026-08-13
- SoilSourced guidancemoderate confidence
- Royal Horticultural Society: Vietnamese coriander — soil
Checked 2026-08-13
- Soil pHSourced guidancemoderate confidence
- Plant Finder — Missouri Botanical Garden: Persicaria odorata — culture
Checked 2026-08-13
- DrainageSourced guidancemoderate confidence
- Royal Horticultural Society: Vietnamese coriander — soil
Checked 2026-08-13
- Water needsHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- DroughtHorticultural consensusmoderate confidence
It is a marsh plant and wilts within hours of drying out.
No external citation — see the evidence type above.
Checked 2026-08-13
- WaterloggingHorticultural consensusmoderate confidence
One of the few herbs that will genuinely stand wet feet.
No external citation — see the evidence type above.
Checked 2026-08-13
- HeatHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Wind and exposureHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
On your soil
Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.
| Soil | Verdict | Why |
|---|---|---|
| Heavy clay | Prefers this soil | Heavy clay suits Vietnamese coriander as it stands: The pH suits it: it wants 5.5 to 7, and this soil is in that range. It tolerates ground that stays wet, which most crops do not. The soil holds moisture, which saves a great deal of watering. |
| Sandy | Works, with one condition | Vietnamese coriander will crop on sandy, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Chalky and alkaline | Struggles here | Vietnamese coriander struggles on chalky and alkaline: The soil is substantially too alkaline for it: it wants pH 5.5 to 7, and this soil sits around 7.8 to 8.5. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering. A container or a raised bed of imported soil sidesteps the problem entirely. |
| Loam | Prefers this soil | Loam suits Vietnamese coriander as it stands: The pH suits it: it wants 5.5 to 7, and this soil is in that range. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering. |
| Silty | Prefers this soil | Silty suits Vietnamese coriander as it stands: The pH suits it: it wants 5.5 to 7, and this soil is in that range. Silt is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering. |
| Peaty and acid | Prefers this soil | Peaty and acid suits Vietnamese coriander as it stands: The pH suits it: it wants 5.5 to 7, and this soil is in that range. It tolerates ground that stays wet, which most crops do not. The soil holds moisture, which saves a great deal of watering. |
| Shallow over rock | Works, with one condition | Vietnamese coriander will crop on shallow over rock, but one thing has to be dealt with first. It has little drought tolerance and this soil dries out fast — it will check and bolt in the first dry spell without watering.Water and mulch will carry it through. On this soil the watering is not optional in a dry spell, which is the difference between a crop and a failure. |
| Made ground and urban soil | Grows well here | Vietnamese coriander grows perfectly well on made ground and urban soil without special measures, though it is not the soil it would choose. |
Not sure which you have? Four hand tests will settle it.
Space and spacing
- Mature height
- 25–40 cm
- Mature spread
- 40–60 cm
- Rooting depth
- 20 cm
- Spacing
- 30–40 cm apart
Where these figures come from
- Mature heightHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Mature spreadHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Rooting depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- SpacingSourced guidancemoderate confidence
- Royal Horticultural Society: Vietnamese coriander — spacing
Checked 2026-08-13
In a container
- Minimum volume
- 5 litres or more
- Minimum depth
- 20 cm
Where the container figures come from
- Minimum volumeHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Minimum depthHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
Ideal in a pot standing in a saucer of water — it is a marginal plant and will not object. The pot also lets it come indoors for the winter, which is how it survives outside a heated greenhouse, and it will crop on a warm bright sill all year.
Where and how you can grow it
Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.
| Method | Suitability | What it needs |
|---|---|---|
| Container | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | 5 litres; Compost kept constantly moist |
| Greenhouse | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Polytunnel | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Windowsill | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Indoor pot | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Hydroponics | Well suitedsourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Traditional dug bed | WorkablesourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Raised bed | WorkablesourceSourced guidancemoderate confidence
Checked 2026-08-13 | |
| Open ground | Not suitablesourceSourced guidancemoderate confidence
Checked 2026-08-13 | Only as a summer plant that will be lost in autumn. |
Growing it
- PropagationTake cuttings in late summer and root them in water on a windowsill. This is the reliable way to keep it going, and far more dependable than trying to carry a large plant through a British winter.
- ProtectionNever let it dry out. This is a marsh plant and a pot that goes dry once will drop most of its leaves, which is the commonest complaint about growing it indoors and is entirely preventable.
- WateringKeep it wet. This is a marginal plant that grows in mud in its native range, and it is one of the very few herbs that will not object to standing in water — a pot in a saucer kept topped up through summer suits it exactly. A plant that dries out goes crisp at the leaf edges quickly and is slow to recover, and drying out is the commonest reason one fails indoors over winter.
- FeedingA balanced liquid feed every two or three weeks through the summer keeps the leaves large and dark; it is grown for leaf and cut often. Ease off from September as growth slows. Pale, small leaves on an indoor winter plant are usually a light problem rather than a feeding one.
- HarvestingCut shoot tips with several leaves attached, taking from all round the plant. It is the one coriander substitute that does not bolt, so there is no window to catch — pick continuously from May to October outdoors, and year-round from a plant kept warm indoors. The flavour is strongest in fresh young leaves and is lost in cooking, so add it at the end.
Where this guidance comes from
- PropagationSourced guidancemoderate confidence
- Royal Horticultural Society: Persicaria — propagation
Checked 2026-08-13
- ProtectionSourced guidancemoderate confidence
- Royal Horticultural Society: Persicaria odorata — care
Checked 2026-08-13
- WateringSourced guidancehigh confidence
- Royal Horticultural Society: Persicaria odorata — cultivation
Checked 2026-08-13
- FeedingSourced guidancehigh confidence
- Royal Horticultural Society: Persicaria odorata — cultivation
Checked 2026-08-13
- HarvestingSourced guidancehigh confidence
- Royal Horticultural Society: Persicaria odorata — harvesting
Checked 2026-08-13
Is it worth putting under cover?
Whether it will grow there is on the methods table above. This is whether the space is well spent, which is a different question and usually the one being asked.
| Structure | What protection is worth | What decides it |
|---|---|---|
| Greenhouse | Only possible under coversourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Frost. A tender perennial that dies outdoors in the first hard frost and keeps going indefinitely under cover. |
| Polytunnel | Extends the seasonsourceGrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file.
Checked 2026-08-13 | Overnight temperature. Glass holds overnight heat that polythene loses, so a tunnel runs cooler at night than a greenhouse in the same garden. For a crop at the edge of its heat requirement that difference decides whether the fruit ripens. |
On a windowsill
source
GrowingHQ editorial positionmoderate confidence
How long the crop is actually productive on an ordinary British windowsill without added light.
- GrowingHQ editorial synthesis — GrowingHQ
Checked 2026-08-13
Growing it without soil
Nearly anything can be grown in a soilless system by somebody with enough equipment. The useful question is whether it is worth it, in which technique, and what goes wrong.
An established soilless crop. Grown this way commercially or routinely by home growers, with predictable results.
source
Sourced guidancemoderate confidence
- Purdue Extension — Purdue University: Hydroponic culinary herbs
Checked 2026-08-13
Among the best soilless herbs there is, and almost never sold as one: it is a marsh plant, so a permanently wet root run is its native condition rather than a compromise.
Techniques that suit it
- Deep water cultureRoots hang in aerated solution. Very productive and very unforgiving of solution temperature — warm solution holds less oxygen and root disease follows.
- Nutrient film (NFT)A shallow stream of solution runs over bare roots in a sloped channel. Cheap and productive for small fast crops; a pump failure kills a crop within hours because there is no reservoir at the roots.
- Ebb and flowA bed of inert medium floods and drains on a timer. The medium holds moisture between floods, which makes it far more tolerant of interruption than NFT.
source
Horticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- Root space
- Small. It roots from every node and is propagated by dropping a cutting in water.
- Lighting
- Needs supplementary light
- pH band
- 5.5–6.5
Where these figures come from
- Root spaceHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- LightingHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
- pH bandSourced guidancehigh confidence
Outside roughly this band, individual nutrients become unavailable even when they are present in the solution — which is why a crop can starve in a full reservoir.
- Purdue Extension — Purdue University: Hydroponic solution management — pH
Checked 2026-08-13
What actually goes wrong
- Warm solution. Above roughly 22 °C the water holds much less dissolved oxygen and root disease follows quickly, which is why summer is harder than winter in an indoor system.
source
Sourced guidancemoderate confidence
- Purdue Extension — Purdue University: Solution temperature and dissolved oxygen
Checked 2026-08-13
No nutrient recipes here
GrowingHQ records pH bands, which are measurable properties of nutrient availability, and deliberately records no EC or PPM targets and no mixing instructions. Published targets vary by cultivar, growth stage, water source and technique, and the figures that apply to your system are on the product you bought.
Harvesting
- When it is readyReady whenever the plant has shoots long enough to cut, which outdoors means May to October and indoors means all year. It does not bolt, so there is no window to miss. Young leaves at the shoot tips carry the strongest flavour; older lower leaves are milder and tougher.
- How to pick itCut shoot tips with several leaves attached, taking from all round the plant — picking it this way is also what keeps it bushy, since a plant left unpicked sprawls into long bare trailing stems. Use fresh and add at the end of cooking, as heat destroys the flavour.
Where the harvest guidance comes from
- When it is readySourced guidancehigh confidence
- Royal Horticultural Society: Persicaria odorata — harvesting
Checked 2026-08-13
- How to pick itHorticultural consensusmoderate confidence
No external citation — see the evidence type above.
Checked 2026-08-13
What goes wrong
| Problem | How often | Notes |
|---|---|---|
| Red spider mite | occasionalsourceHorticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13 |
Sources for this page
GrowingHQ editorial synthesis · Plant Finder · Purdue Extension · Royal Horticultural Society
Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-15.