How to Grow Grass pea

Lathyrus sativus · Also called: Khesari, Khesari dal, Kesari, Teora, Lakh, Chickling pea, Chickling vetch, Almorta

Grass pea plants in flower in Bangladesh, carrying single blue pea-shaped flowers above narrow pointed leaflets on thin sprawling stems.

Photo: Rahat Rahim, CC BY-SA 3.0 (Wikimedia Commons)

Grass pea is the crop that yields when everything else has failed. It survives drought that kills wheat and flooding that kills chickpea, it grows on leftover soil moisture with no ploughing, no fertiliser and no watering, and it goes on producing on ground too poor and too dry for anything else. Ethiopia, India, Bangladesh, Nepal, Pakistan, Spain and Ukraine all grow it. That reliability is exactly why it carries a warning: people eat it heavily in the years when there is nothing else, and eating it as most of the diet for months is what causes harm. Grown and eaten sensibly it is one of the most valuable insurance crops a poor household can have.

Growing Grass pea, Stage by Stage

1. Get the land ready — Usually no land preparation at all, because the seed goes into a standing crop.
2. Choose your seed and planting material — Ask for a low-substance variety by name. This is the most important decision in the crop.
3. Sow the seed — Broadcast into the standing rice before it is cut, so the seedlings use the moisture that is left.
4. Water — None. The crop lives on what the soil already holds, and that is the point of it.
5. Weeds and feeding — Almost nothing to do. A thick stand looks after itself and feeds itself.
6. Flowering and pod set — Single blue, pink or white pea flowers, followed by short flat pods with a few seeds each.
7. Watch for trouble — Very little troubles this crop, which is much of its value.
8. Harvest — Pull the whole plants when the pods have dried, in the cool of the morning.
9. Prepare, store and sell — How this seed is prepared and how much of it is eaten matters more than anything else in the guide.

Common Problems & Troubleshooting

If you see: Weakness, stiffness or cramping in the legs in someone who has been living largely on grass pea for weeks or months, especially a young man doing heavy work.

It likely means: The illness this crop is known for. It comes from eating grass pea as most of the diet over a long period, and the damage to the legs does not heal.

Do this: Stop relying on grass pea as the main food immediately and get other food into the diet.

If you see: Seed saved from an old local crop being planted year after year with no idea how much of the harmful substance it carries.

It likely means: It is almost certainly a traditional high-substance type. Low-substance varieties have been bred and released, and most growers have never been offered one.

Do this: Ask a licensed dealer or your extension office for a low-substance variety by name.

If you see: Grass pea cooked as a thick dish with no water thrown away, or ground into flour and used without soaking.

It likely means: The preparation keeps the harmful substance in the food. It dissolves in water, so it only leaves if the water is discarded.

Do this: Soak the seed in plenty of water for several hours and throw that water away.

If you see: Very few seedlings coming up after broadcasting into a standing rice crop.

It likely means: The sowing was mistimed. The seed needs saturated soil at sowing, and if the field has already begun to dry, it will not establish.

Do this: Broadcast one to two weeks before the rice is cut, while the soil is still saturated.

If you see: A buyer refusing grass pea, or a market where it cannot legally be sold for food.

It likely means: Some countries and states restrict the sale of this seed for human food because of the illness it can cause.

Do this: Find out the rules where you are before planning to sell, rather than after harvest.

If you see: Plants yellowing and dying in patches in the lowest part of the field after water stood for several days.

It likely means: Standing water. Grass pea tolerates wet ground far better than most pulses, but not water standing for a long time.

Do this: Make sure surface water can drain off the field.

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 seed and straw 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.

Never let this become most of what a household eats.
Ask for a low-substance variety by name. It is the real answer.
Soak and boil in plenty of water. Throw both waters away.
The young leaves and shoots are safe. The concern is the seed.
Broadcast into standing rice a week or two before it is cut.
Sow while the soil is still saturated. There is no watering after.
No ploughing, no fertiliser, no irrigation. That is the point.
Leave the rice stubble. It shelters the seedlings.
Pull the plants in the cool morning when the pods are brown.
Keep the straw. It is fodder and it is worth money.

Test Yourself: Identification

What does the plant look like in flower?

Can the leaves be eaten, and what do they look like when sold?

What do the pods look like, and when is the seed ready?

Honest Limits of This Guide

This guide gives the safety advice that agricultural and nutrition authorities give: grass pea is safe as part of a mixed diet, harmful when it becomes most of the diet for months, soaking and boiling in plenty of discarded water reduce the risk, and low-substance varieties reduce it far more. It is not medical advice. Anyone showing weakness or stiffness in the legs needs a doctor, not a farming guide.
How much of the harmful substance a crop carries depends on the variety and on the growing conditions, and this guide cannot measure yours. That is precisely why it says to ask for a named low-substance variety rather than to rely on preparation alone.
The sale of grass pea for human food is restricted in some countries and states and not in others, and the rules change. Check locally before planning to sell, because this guide cannot tell you what applies where you are.
Timings are given in days from sowing and around the rice harvest rather than in named months, because the crop is sown into standing rice and that date differs everywhere.
Grass pea is under-recorded because it is grown as a fallback on land already counted for another crop, so the yield ranges here are broader and less certain than those in this library's grain guides.

Sources

GBIF Backbone Taxonomy species-match record for Lathyrus sativus L. — Global Biodiversity Information Facility (GBIF), Copenhagen (source)
EPPO Global Database — Lathyrus sativus (EPPO code LTHSA) — European and Mediterranean Plant Protection Organization (EPPO), Paris (source)
FAO and ICARDA work on grass pea as a famine-insurance crop, and on lathyrism and low-toxin varieties — Food and Agriculture Organization of the United Nations (FAO), Rome (source)
Lathyrus sativus (grass pea) — CABI Compendium datasheet — CABI, Wallingford (source)

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