How to Grow Water spinach

Ipomoea aquatica · Also called: Kangkong, Kangkung, Rau muống, Ong choy, Hollow-heart vegetable, Water morning glory, Swamp cabbage, Kalmi shak

Water spinach growing with long trailing stems, arrow-shaped leaves and a pale trumpet-shaped flower, photographed near Kahuku on Oahu, Hawaii.

Photo: Eric Guinther, CC BY-SA 3.0 (Wikimedia Commons)

Water spinach is one of the fastest and cheapest green vegetables in the world. It is ready to cut about three or four weeks after planting and then goes on being cut every week or two for months from the same plants. It grows in water that is useless for anything else, it needs almost no inputs, and it is an everyday green across South East Asia, southern China, South Asia and much of Africa. For a household beside a pond or a flooded field it turns standing water into a steady supply of food and a small regular income.

Growing Water spinach, Stage by Stage

1. Get the land and the water ready — Choose your water first, because the water decides whether the crop is food or a hazard.
2. Choose your seed and planting material — Cuttings from a healthy clean planting, or seed for a dryland bed.
3. Plant — Push the cuttings into wet mud, or sow seed thickly on a wet bed.
4. Water — Never let it dry out, and keep the water moving and clean rather than stagnant.
5. Weeds and feeding — Feed it after every cutting, because you are asking it to regrow again and again.
6. Growth and flowering — Flowering is a signal, not a crop, because a flowering stem has stopped making tender shoots.
7. Watch for trouble — Leaf-eating insects and a white blistering disease, and the water itself.
8. Harvest — Cut the tender tips above a node and leave the base, so the plant comes again.
9. Wash, keep and sell — Wash in clean water, sell the same day, and be honest about where it was grown.

Common Problems & Troubleshooting

If you see: A wonderful heavy crop growing in a roadside drain, a sewage channel or a ditch taking waste water.

It likely means: Exactly what it looks like: this plant thrives on the nutrients in waste water. It also takes up what else is in it, and that goes into the food.

Do this: Do not harvest it for food and do not sell it, however good it looks.

If you see: A bed that was cut once and then barely grew back, with bare stubs or plants pulled out altogether.

It likely means: It was cut too low, or pulled rather than cut. This crop regrows from what is left behind.

Do this: Cut just above a node, leaving the lower stem in place.

If you see: Stems that are stringy, tough and unpleasant to eat, which buyers will not take.

It likely means: They were cut too late, or the planting has aged and gone woody.

Do this: Cut every seven to fourteen days rather than waiting for length.

If you see: Shoots that were crisp when cut arriving limp and yellowing, worth almost nothing.

It likely means: Heat and time. This is one of the fastest-wilting vegetables there is.

Do this: Cut in the cool of the early morning and never in the middle of the day.

If you see: White raised blisters on the undersides of leaves with pale yellow patches showing on top, worst in wet weather.

It likely means: A white rust disease. It spoils the leaf for sale even though the plant carries on.

Do this: Cut the crop more often, since older growth is taken first.

If you see: The crop spreading out of the planting into open water, drains or a waterway and choking it.

It likely means: It is doing what it does. This plant grows extremely fast on water and is treated as a serious weed in several countries for exactly that reason.

Do this: Contain the planting to a pond, tank or bed you control.

Yield & Market Value

Growing the crop is only part of the job. The last part is knowing what a normal harvest looks like where you are, and knowing what your bundles are worth before you agree a price with anybody.

Remember It This Way

If you forget every other page of this guide, keep these lines. They are the whole crop, in order, short enough to carry in your head.

The water decides everything. Never grow it in a drain.
It takes up whatever is in the water it stands in.
Cook it rather than eat it raw if the water is not certain.
Push cuttings into wet mud. Two thirds above the surface.
Never let it dry out. It stops the moment it does.
Keep the water moving, not sitting still.
Cut above a node and leave the base. It grows again.
Cut every week or two. Cutting is what keeps it coming.
Feed it after every cutting. You are asking a lot of it.
Cut in the cool morning. It wilts within hours.

Test Yourself: Identification

What does the plant look like growing?

Why are the stems hollow, and what does that tell me?

The crop is flowering. Is that good?

Honest Limits of This Guide

The water-quality warning in this guide is the most important thing in it. This crop is grown in standing water in many places, and it genuinely does take up what is in that water. The guide can tell you to check your source and to cook rather than eat raw when you are unsure; it cannot test your water, and where there is real doubt a local health or agriculture office can advise.
The parasite risk from eating water-grown plants raw is real and well documented in parts of Asia. The practical advice here — wash in clean water and cook rather than eat raw when the source is uncertain — is the standard advice, but this is a farming guide and not medical advice.
Water spinach is a declared weed in several countries because it spreads rapidly in waterways, and growing it may be restricted or prohibited where you are. Check before planting, since this guide cannot know your local law.
Timings are given in days from planting and between cuttings rather than in named months, because this is a warm-season crop grown nearly all year in the tropics.
This crop is barely recorded in national statistics because it is grown on pond edges and sold locally, so the yield ranges here are broad estimates rather than measurements.

Sources

GBIF Backbone Taxonomy species-match record for Ipomoea aquatica Forssk. — Global Biodiversity Information Facility (GBIF), Copenhagen (source)
EPPO Global Database — Ipomoea aquatica (EPPO code IPOAQ) — European and Mediterranean Plant Protection Organization (EPPO), Paris (source)
FAO and World Vegetable Center work on aquatic and leafy vegetables, and public health guidance on produce grown in waste water — Food and Agriculture Organization of the United Nations (FAO), Rome (source)
Ipomoea aquatica (water spinach) — CABI Compendium datasheet — CABI, Wallingford (source)

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