How to grow cotton

Buy certified, treated seed from a registered dealer — a sealed, labelled bag with the variety name and this season's packing date. The seed dressing (a chemical coat on the seed) shields the young seedling from the first sap-sucking pests, thrips and jassids.

Choose a variety that suits how long your rains last. If bollworm is bad in your area and it is sold near you, ask about a Bt variety — its leaves carry built-in bollworm protection — but know you still scout and still spray for the pests Bt does not stop (jassids, whitefly, stainers).

Buy enough basal fertiliser for your field — your recommendation gives the exact type and amount. Cotton wants nitrogen and plenty of potash; a compound that also carries a little boron helps the plant keep its squares (flower buds) and bolls.

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

In the month before sowing, clear weeds and old cotton stalks off the planting lines. Chop and work the old stalks in early — they shelter bollworm and stainers right through the off-season.

Loosen the soil to about 15–20 cm — a spade's blade deep — so the taproot can drive down and rain can soak in.

Break the clods on top to a fine, crumbly tilth. Seed dropped into big clods sits in air pockets and comes up in gaps.

Level the bed and make sure water drains away — cotton hates wet feet. On a slope, work across the slope and make ridges or basins to catch the rain; in low, wet spots, sow on a ridge so the roots sit above standing water.

Sow into warm, moist soil. Cotton needs real warmth to sprout — below about 15 °C it barely moves. Simple check at dawn: the soil feels warm, not cold, to the back of your hand, and the cold snaps have passed. When in doubt, wait a few days rather than sow into cold ground.

Open your rows about 90 cm apart — a good stride — wide enough to walk, spray and pick between later.

Sow along the row about 3–5 cm deep — one finger-joint — a touch deeper in dry, sandy soil, shallower in heavy soil. Drop a few seeds per station (you will thin to one later) and space the stations about 25 cm apart — a hand-span.

Cover and firm the soil over the seed so it sits snug in moist earth. It should come up in 5–10 days — slower if the soil is on the cool side.

From about a week after sowing, walk the field twice a week. Cross it in a big "W" so you cover the corners and the middle, not just the edge by the path.

At about 10 stops, look closely at 10 plants — the growing tip and the undersides of the young leaves, where the sap-suckers hide.

Thrips: look for silvery or bronze scarring on the young leaves, leaves that curl upward, crinkle and pucker, and stunted, ragged seedlings. The insects are tiny slivers, hard to see — the leaf damage is your signal.

Jassids (leafhoppers): look for small, wedge-shaped green hoppers that dart sideways when you touch a leaf, and leaf edges that yellow, then turn bronze-red and curl downward — this scorched look is called "hopperburn". Act at about 2–3 nymphs (young hoppers) per leaf.

Also count the gaps — stations with no plant — so you know whether the stand is thin.

Write down what you find and where. If thrips or jassids are over threshold, open the matching pest guide and act; if the stand is thin, plan to keep every seedling when you thin.

Thin about 13 days after the seedlings come up — once they are big enough to handle, but before they crowd each other.

At each station, pick out the single strongest, healthiest seedling to keep.

Snip or pinch the extra seedlings off at ground level — do not pull them, or you tear the roots of the one you are keeping.

Aim for one plant per station, evenly spaced about a hand-span (25 cm) apart down the row.

From about two weeks after sowing, keep walking the "W" twice a week, checking about 10 plants at each of 10 stops.

Bollworm (first eggs): on the top leaves and near the squares, look for tiny, round, ridged, creamy-white eggs laid one at a time, for young caterpillars, and for squares that yellow, flare open and drop to the ground.

Jassids: check leaf undersides for small green wedge-shaped hoppers and edges that yellow and curl down; act at about 2–3 nymphs (young hoppers) per leaf.

Cotton aphids: look for clusters of small, soft green or black insects on the undersides of leaves and on the tips, a sticky, shiny film (honeydew) on the leaves below, ants running up the stems, and later a black sooty mould growing on the stickiness.

Note the counts and where. If any pest is over its threshold, open its guide and act; otherwise leave the natural enemies to keep working.

Weed early, between about two and five weeks after sowing, before the weeds grow taller than the cotton.

Hoe shallowly between and along the rows — deep hoeing close to the plants cuts cotton's spreading feeder roots.

Pull or hoe weeds out roots and all where you can; slashing only the tops lets many spring straight back.

Time this weeding just before you feed the crop, so the fertiliser goes to the cotton and not the weeds. In dry areas, leave the pulled weeds lying between the rows as a mulch to hold moisture.

Feed when the first squares appear, about 30–40 days after sowing.

Use the type and amount your recommendation gives — a balanced compound carrying nitrogen and potash. As a rough picture it is about a bottle-cap beside each plant, but follow your plan for the exact rate.

Band it in a line about a hand's width (10 cm) to the side of the row — never on top of the plants — on moist soil, then cover it or scratch it in so it does not gas off or wash away.

Keep fertiliser off wet leaves (the grains stick and scorch them), keep it away from food, water and children, and wash your hands afterwards.

From the first flowers, walk the field every 2–3 days — bollworm moves fast now. Check about 10 plants at each of several stops.

Bollworm complex: on the top leaves and near the squares, look for tiny, round, ridged eggs, small caterpillars, and the tell-tale round bore-holes in squares and young bolls — often with wet droppings at the hole and shed squares on the ground underneath. Spray at about 1 caterpillar per plant, 5–10 damaged squares or bolls in 100, or when about 1 plant in 10 carries small caterpillars.

Whitefly: brush a plant — if a cloud of tiny white flies lifts off the leaf undersides, check the count. Act at about 5–10 adults per leaf. Look too for sticky leaves and black sooty mould below.

Stainers: look on and around opening bolls for clustered red-and-black bugs. Act at about 3 bugs per metre of row, and clean up trash and stray plants they breed in.

Write down the counts at every stop. Spray only what has crossed its threshold — and rotate the chemical group each time.

Spray only when scouting shows a pest has crossed its threshold (about 1 bollworm caterpillar per plant, 5–10% damaged squares or bolls, or a sucking pest over its count) — not by the calendar.

Measure the dose with the cap supplied and mix it into a full knapsack (15–20 litres) of water. More chemical than the label says does not kill more — it just poisons you and breeds resistance.

Spray to wet the plants all over, undersides too, until just before it drips — that is where the eggs, young caterpillars and whitefly sit.

Rotate the chemical group every spray (the bollworm complex builds resistance fast). Ask the dealer which group each product belongs to and keep a simple note of what you used.

Spare the helpers: spray in the cool of early morning or evening when bees and useful insects are less active, and only spray what needs it.

Protect yourself: wear a long-sleeved shirt, cover your nose and mouth, spray with the wind behind you, keep people and animals out of the field, and wash with soap afterwards. Keep spray off any food crops.

Respect the pre-harvest interval — the number of days the label says to wait between your last spray and picking, so no poison stays on the lint and seed.

Keep the soil moist right through flowering — water every 5–7 days, more often in heat and on sandy soil that dries fast.

Never let the crop wilt at flowering, even for a day; a wilted plant drops its youngest bolls first.

Water in the cool of the day to lose less to the sun, and drain any low spots — cotton fruits badly in both drought and waterlogging.

From about a month after first flower through boll fill, walk the field twice a week, checking about 10 plants at several stops — squares, flowers and especially the bolls.

Bollworm in bolls: look for round bore-holes in the filling bolls, wet droppings at the hole, and caterpillars inside. Spray at about 1 caterpillar per plant or 5–10 bored bolls in 100.

Stainers: look for clustered red-and-black bugs on the bolls and, on any open bolls, yellow-brown stains on the lint with shrivelled, stained seed inside. Act at about 3 bugs per metre, and clear away trash and stray plants.

Boll rot: search the lower, shaded, crowded part of the plant — worst after rain — for bolls that turn brown or black, slimy or hard and rot shut instead of opening white.

Note counts and where. Spray the bollworm and stainers on threshold; for boll rot, open up a rank canopy and pick off and remove the rotted bolls before it spreads.

Feed potash as the bolls start to fill — from about a month after first flower — using the type and amount your recommendation gives.

Band it a hand's width (10 cm) to the side of the row on moist soil, then cover or scratch it in so it reaches the roots and does not wash off.

Keep it off wet leaves and away from food, water and children, and wash your hands afterwards.

Keep watering through boll fill — every 7–10 days, depending on heat and soil — while the plant is still green and setting weight into the bolls.

As the lower leaves yellow and the first bolls crack open, ease off the water so the opening lint stays dry and clean.

Stop watering once most bolls are mature and opening, so the crop can dry down for a clean pick.