How to grow sesame

Pick a field that drains freely — gently sloping, with sandy-loam or loam soil where water never sits. Sesame actually does well on lighter, poorer land that heavier crops find too weak, so save your best bottomland for something else.

Never choose a low spot, a vlei or dambo, or anywhere water pools after heavy rain. If you can, remember the field after a storm last season — if puddles stood there even a day, sesame will drown there too.

Avoid heavy clay or a hard pan just under the surface that traps water. If your only land is flat, plan now to make ridges or raised beds so the plants sit above any wet.

Think about last season's crop. Sesame after a cereal like maize or sorghum is good. Do not grow sesame after sesame on the same land year after year — it builds up wilts and rots in the soil that attack the roots and stems.

Buy fresh, clean seed of a recommended variety from a trusted dealer. Where you can, choose a shatter-resistant (non-splitting) type — its capsules hold the seed longer and give you a wider, calmer harvest window.

Match the seed colour to your market: white seed usually fetches the best price for food and export, while brown and black types are hardier. Ask your buyer what they want before you choose.

Get the seed rate your recommendation gives for your field size — sesame needs only a little seed because it is so tiny — plus some dry sand or wood ash to mix it with at sowing.

Buy the basal (starter) fertiliser your recommendation lists — usually a compound carrying phosphorus plus part of the nitrogen. Sesame is a light feeder: do not buy or apply more than you are advised.

Store seed and fertiliser dry, off the floor, and away from food, water and children. Keep the receipt and label in case the seed comes up poorly.

Plough or dig, then break the soil down fine — work the top until it is crumbly like flour or fine sand, with no clod bigger than a pea. Rake off any trash, roots and stones.

Level the surface smooth and even. Bumps and hollows bury some seed too deep and leave the rest lying on top.

Firm the bed lightly — walk it, roll it, or pat it down with the back of a hoe. A loose, fluffy bed swallows the tiny seed too deep to climb out; the seed wants firm, moist soil pressed around it.

If your land is flat or holds water, make raised ridges or beds now, while the soil works easily, so the young plants sit above any standing water.

Use the basal fertiliser and the amount your recommendation gives — usually a compound carrying phosphorus plus half of the season's nitrogen (the other half is fed later, once the crop is growing fast).

Work it in just before or as you sow — band it along the rows or mix it through the top of the bed. Keep it below and to the side of where the seed will sit, never touching the seed, or the tiny sprout burns.

Sesame also answers to a little boron — the trace nutrient that helps flowers set into capsules. If your recommendation includes boron, apply it now with the basal. Never add extra on a guess: too much boron poisons the crop.

Keep the dose modest. Too much fertiliser — especially nitrogen — makes sesame grow tall and leafy, fall over (lodge), and set fewer capsules. A light feeder wants a light hand.

Sow only into warm soil. Sesame will not come up in cold ground — wait until the soil is warm to the touch and there is moisture in the seedbed.

Mix the seed with a carrier so you can spread it thinly: about 1 handful of seed to 5–10 handfuls of dry sand or wood ash. Mix it well in a tin or bucket — the sand carries the tiny seed evenly and lets you see where it has fallen.

Open shallow furrows 30–45 cm apart — about two hand-spans between rows (a hand-span is your spread hand, roughly 20 cm). Trickle the seed-and-sand mix thinly along each furrow.

Cover only lightly — just 1.5–3 cm, less than one finger-joint deep. A thin blanket of fine soil is all it needs; you should almost still see the line of the row. Deep sowing is the number-one killer of a sesame stand — the seed runs out of strength before it reaches the light.

Firm the row lightly with your foot, a light roller, or the back of a hoe, so the soil presses around the seed and holds the moisture in.

From a few days after sowing, walk the rows every 3–4 days and look closely — the seedlings are thread-thin at first and easy to miss.

Check the stand: are the rows filling evenly, or are there bare stretches? Note the big gaps and re-sow them while the soil is still moist and the crop is only days old.

Look for the webber (a leaf-rolling caterpillar): the young sesame webber spins fine silk over the top leaves and growing tip and feeds hidden inside, so the shoot tip looks stuck together, folded, or wilted. Open a webbed tip and you may find a small greenish caterpillar — this same pest bores into the capsules later, so knock it back now.

Look for toppling seedlings (damping-off): seedlings that flop over with a thin, dark, water-soaked pinch right at the soil line, usually in the damp patches. It is the soil telling you it is too wet.

Note where the trouble is. If the webber is spreading, open its guide and act. If seedlings are damping off, ease off the water and open up the drainage.

Thin when the seedlings are 5–10 cm tall (roughly 10–14 days after sowing), while the extras still pull out easily.

Leave one strong seedling every 5–10 cm along the row — about two finger-joints apart (a finger-joint is one section of your finger, 3–5 cm). Keep the sturdiest and remove the rest.

Pull or pinch out the extra seedlings gently, holding the soil down around the one you keep so you do not lift its roots too. Thinning is easiest when the soil is slightly moist.

Fill any bare gap by moving a thinned seedling with a ball of soil into it and watering it in — or leave the gap if the crop is already too old for a fill to catch up.

Only if you can irrigate. From sowing until the seedlings are well up, keep the top of the seedbed just damp — light, frequent watering, never a heavy soaking.

Water gently — a fine spray or a careful can, never a hard flow that washes the tiny seed into heaps or beats the surface into a crust.

Water little and often — about every 3–4 days, more in heat and on sandy soil. Push a finger in; wet the surface again when the top centimetre is drying.

Never let water stand. Sesame drowns in waterlogged soil — if puddles form or the ground stays soggy, stop and let it drain.

Do the first weeding early — about 2 weeks after sowing (around 15 days) — as soon as you can tell the crop rows from the weeds. Do not wait; sesame loses ground fastest while it is small.

Do the second weeding about 2 weeks later (around 30 days after sowing), before the plants close over and shade the ground themselves.

Hoe shallowly between and along the rows — sesame's roots run near the surface, and deep hoeing close to the plants cuts them. Weed by hand right next to the stems.

Take care not to uproot or bury the young sesame — the seedlings snap and smother easily while they are small.

Around 4 weeks after sowing (about 30 days), top-dress (feed the growing crop) with the rest of the nitrogen your recommendation gives — the second half of the split.

Band it in a thin line about a hand's width (10 cm) out to the side of the rows, not on top of the plants, and keep the fertiliser off the leaves.

Apply onto moist soil — just after a weeding or a light rain — and lightly cover it or water it in, so it feeds the roots instead of gassing off into the air.

Keep the dose to what is recommended. Too much nitrogen makes sesame grow tall and leafy, fall over (lodge), and delay its capsules — feed it with a light hand.

Walk the field every 3–4 days, checking plants right across it — not just along the edge by the path.

Sesame webber (the young stage of the capsule borer): look for top leaves and shoot tips webbed together with fine silk, folded or stuck, with a small caterpillar feeding inside and dark specks of droppings. It webs the tips now and will bore into the flowers and capsules later, so hit it now.

Leaf spot: look for small brown or dark spots on the leaves, sometimes with a paler centre or a ring; badly spotted leaves yellow and drop. It spreads fastest in warm, wet, crowded stands.

Note how widespread it is. If the webber or leaf spot is spreading, open the matching guide and act — and pull off and destroy any badly diseased leaves or plants.

From the first flowers (about 35 days after sowing), scout every 2–3 days — the tightest watch of the whole season. Look over plants right across the field.

Phyllody: look for plants whose flowers have turned into little green leafy tufts instead of normal bell flowers, with the top growth bunched, leafy and bushy — a 'witch's-broom' look. These plants are sterile: they will never set seed, and they pass the disease on to others.

Sesame gall midge: look for flower buds and young capsules that are swollen, deformed, and never open properly — hard little galls where a normal capsule should be forming.

Capsule borer: look for flowers and green capsules with small bore-holes and sawdust-like droppings, and flower clusters webbed together. This is the grown-up stage of the webber you watched for earlier.

Mark or note the affected plants. Pull out the phyllody plants at once (see the next task); if the midge or borer is spreading, open the matching guide and act.

As you scout (from about 35 days after sowing), whenever you find a plant with leafy green tufts where its flowers should be, or a bushy witch's-broom top setting no capsules, act on it straight away.

Pull the whole plant out, roots and all. Do not just cut the top — the disease is in the whole plant.

Carry it right out of the field and burn or bury it. Left lying in the rows it still feeds the leafhoppers that carry phyllody onto your healthy plants.

Keep doing this every 3–4 days through flowering — new sick plants keep appearing as the disease spreads.

Only if you can irrigate. From the first flowers (about 35 days after sowing) through pod-set, keep the soil evenly moist — this is the most important watering of the season.

Water every 5–7 days, more often in heat and on sandy soil. Do not let the crop wilt while it is flowering.

Give it a good soak that drains away — never a flood that stands. Even a day or two of standing water at flowering can rot the roots and undo everything.

Water in the cool of the morning or evening, so less is lost to the sun.

Walk the field once a week through pod-fill, looking over the whole crop.

Watch the lowest capsules: when the bottom pods start turning from green to yellow-brown, maturity is coming and harvest is near. This is your main signal — check it every visit.

Birds: look for flocks feeding on the crop and for split, emptied capsules near the field edges as the seed ripens. Ripe sesame spills easily and birds learn fast — scare them off or plan to harvest promptly.

Charcoal rot: look for scattered plants that wilt and die early, with a greyish, shredded lower stem that shows tiny black specks like soot when you scrape the skin. It strikes hot, dry, stressed crops — pull and remove badly affected plants.

Late leaf spot: dark spots and yellowing on the leaves. It is not worth chasing this late, but note it for next season's rotation.

Only if you can irrigate. Through early pod-fill, keep giving a moderate drink every 7–10 days while the plant and leaves are still green, so the seed fills out.

As the lower leaves yellow and the bottom capsules turn, cut back the water.

Stop watering once the crop starts to dry down and the lowest pods are browning — from here it needs to dry, not drink.

Never waterlog at any point; a soggy finish brings on the stem and root rots that ruin a standing crop.

Judge maturity by the lowest capsules: harvest as soon as the bottom pods turn from green to yellow-brown and the very first ones just begin to split, most leaves have yellowed and dropped, and roughly three-quarters (about 75–85%) of the capsules are browning. Do not wait for the whole plant to dry — by then it is already shattering.

Cut in the cool of the early morning, when the pods are least brittle and there is a little dew, so they shatter and spill less as you handle them.

Cut the whole plants near the ground with a sickle or knife — or pull them up if the soil is loose.

Tie them into small bundles — about an armful each — and stand the bundles upright in little shocks (stooks), tops leaning together so air moves through, in the field or on a clean drying floor or tarpaulin.

Handle gently and as little as possible — every rough knock spills seed from the pods that have already split.

Leave the stooks standing to cure in the sun for about 7–14 days, until the capsules are fully dry, brittle, and splitting open.

Stand them on a clean, dry surface — a tarpaulin, mat, or swept threshing floor, never bare soil — and keep them off wet ground.

Cover the stooks or move them under shelter if rain threatens, then set them back in the sun. One soaking undoes days of curing and starts mould.

The seed that spills from the first pods to split can be caught on the sheet beneath — so cure the stooks over the cloth you will thresh onto, and lose nothing.

Once the capsules are dry and splitting (after curing), turn the bundles upside-down over a clean cloth or tarpaulin and shake or tap them gently — the ripe seed rains out. Beat lightly only if you must; hard threshing breaks the seed.

Repeat over several days. Sesame ripens from the bottom up, so more pods split each day — shake the bundles again and again until they give no more seed.

Winnow the seed clean: on a breezy day, pour it slowly from one container into another (or use a winnowing basket) so the wind carries off the chaff, bits of pod and dust. Clean seed keeps far better.

Check it is dry enough to store: bite or press a seed — it should be hard, with no give. If it dents or feels soft, spread it thin in the sun and dry it more before bagging — do not store it yet.

Store the clean, hard-dry seed in sealed bags or clean, dry containers, off the floor, in a cool dry place. Sesame's high oil turns rancid if it is stored damp or warm — dry and sealed is what keeps it good.