How to grow cassava

Pick a field that gets full sun all day — cassava is a sun-lover and grows thin and weak in shade.

Choose light, sandy or sandy-loam soil that water drains through quickly — cassava makes the best roots in loose soil it can push into.

Avoid low, wet spots where water sits after rain — waterlogged soil rots the roots and invites root rot.

Avoid heavy clay, hardpan, stony or salty land — the roots come out small, forked and hard to lift.

If your only land is a bit heavy or wet, plan to plant on ridges or mounds (see the ridging task) to lift the roots above the wet.

Choose your mother plants before you cut — walk a healthy, vigorous stand and mark plants with dark-green, normal-shaped leaves and no mottling, yellow patterns, twisting or brown stem streaks.

Use resistant or certified clean planting material if you can get it — it is the best possible start against CMD and CBSD.

Take the middle, mature part of the stem — the older brown, woody wood, not the soft green tip and not the very hard old base. Stems from plants 8–18 months old are best.

Pick stems at least as thick as your thumb (2 cm or more) — fat stems store more food to push out strong sprouts and roots.

Handle stems gently and keep them in the shade — don't strip the bark or let them dry out in the sun.

Where bacterial blight or mealybug is a problem, dip the stems in hot water (about 50 °C — hot, but you can still dip a finger in for a moment) for about 50 minutes before planting to kill pests and germs riding on the stem.

Do this on heavier or wetter land — on light, sandy, free-draining soil you can simply plant on the flat.

Loosen the soil first to about a hoe-blade deep (15–20 cm) so the roots can push down.

Build ridges or round mounds about a hand-span high (15–20 cm) — high enough to keep the roots above where water sits.

On a slope, run the ridges across the slope, not up-and-down, so they catch the rain and slow the soil from washing away.

Remember cassava is not a hungry crop for nitrogen — it needs mostly potassium (K) to fill the roots. Don't pour on nitrogen fertiliser; it grows big tops and small roots.

Spread well-rotted manure or compost — dark, crumbly, no strong smell — evenly across the whole field and work it in. If you place it by the planting spot instead, use only a small handful per hole — don't move the whole field's dose into the holes, or it over-concentrates and burns the young cutting. (Fresh, un-rotted manure burns it too, and brings weed seeds.)

If you use a bought basal, choose one that carries potassium — your recommendation gives the type and amount for your field.

Work it into the topsoil before you plant, so it is ready where the young roots will grow.

Cut each stem into stakes about as long as your forearm (20–25 cm), each with 5–7 buds (nodes) — the little bumps that sprouts grow from. Cut straight across, and don't split or crush the wood.

Know which way is up: the buds and leaf-scars point upward on the growing plant. Plant the stake the same way up — an upside-down stake sprouts poorly or not at all.

In normal soil, push the stake in upright or at a slight lean (about 45°), with two-thirds buried and a third above ground, buds pointing up.

In hot, dry areas, lay the stake flat and cover it about a hand's width deep (5–10 cm) — buried this way it stays moist and roots along its whole length.

Space plants one long stride apart each way (about 1 m × 1 m) — cut a stick to 1 m as a measuring guide. This gives about 10,000 plants per hectare.

On wet or heavy land, plant on the ridges or mounds you made. Firm the soil around each stake so it stands and grips well.

Once a week, walk right across the field in a big 'W' so you cover the corners and the middle — not just the edge by the path.

Check that stakes are sprouting — green shoots pushing from the buds. By 1–2 weeks most should show; mark any that are still bare.

Gently wiggle a few bare stakes. If one pulls out hollowed, soft or eaten inside, that is termites — common in dry, sandy fields and on stakes that dried out.

Look for gaps — stations where the stake has rotted, dried or been eaten and nothing is coming — and count them, so you know whether to gap-fill.

Glance at the first leaves for yellow mottling or twisting (CMD) — pull out any clearly sick sprout straight away so it can't seed disease into the field.

About 2–3 weeks after planting, walk the rows and count how many stakes have sprouted against how many you planted.

Work out the share that came up — for example, 90 sprouted out of 100 planted = 90%.

90 or more in every 100 (90%+) → a good stand, carry on.

If it fails — fewer than 90 in 100 sprouted → gap-fill the empty stations in the next few days with fresh, healthy stakes (see the gap-fill task), while there is still time for them to catch up.

Go to each gap — a station where the stake rotted, dried or was eaten and nothing has sprouted.

Pull out the old dead stake so the new one has clean soil to root into.

Plant a fresh, healthy stake the same way as before — right way up, two-thirds buried, taken from a clean mother plant.

Do it within the first 3 weeks, and water the new stakes in if the soil is dry — stakes planted much later sit in the shade of the older plants and never make a proper root.

Keep the soil around the stakes moist but not waterlogged through the first few weeks while they root.

If there is no rain, water about once a week — more often on hot days and on fast-draining sandy soil.

Check with a finger: water when the top few centimetres are dry.

Once the plants are well sprouted and rooted, ease off — established cassava is very drought-hardy and needs little extra water.

Every 1–2 weeks, walk the field in a big 'W' and look closely at the young top leaves across the field — that is where trouble shows first.

Mosaic (CMD): yellow-and-green mottled, patchy, twisted or shrunken leaves. Mark the plant to rogue (pull) it.

Brown-streak (CBSD): yellow blotches along the veins and brown streaks on the green stems. The real damage is a brown rot inside the roots you can't yet see, so never ignore it.

Whitefly: tiny white flies on the undersides of the young top leaves that fly up in a little white cloud when you shake the plant — these are what carry mosaic and brown-streak from sick plants to healthy ones, so the more you see, the faster you must rogue any sick plant.

Green mite: fine yellow speckling and tight, bunched 'candlestick' tips on the growing point — worst in the dry season.

Mealybug: white, cottony clusters on the tips and leaves, with bunched, stunted growth.

Bacterial blight: angular dark, water-soaked leaf spots, wilting tips and gum oozing on the stems — often after heavy rain.

Rogue every virus-sick plant on sight, and leave the helper insects alone — a tiny wasp and predator mites quietly control mealybug and green mite for free.

Start weeding early — by about 3 weeks after planting, before the weeds get bigger than the young cassava.

Weed again every few weeks to keep the field clean right through the first 8–12 weeks (about 2–3 months) — the make-or-break weed-free window.

Hoe shallow near the plants — cassava's feeding roots and the swelling storage roots sit close to the surface, and deep hoeing cuts them.

Once the canopy closes and shades the ground, the plants smother most weeds themselves and you can ease off.

As you scout, mark any plant with mosaic mottling (CMD) or brown stem streaks (CBSD) — these viruses don't heal and no spray cures them.

Uproot the whole plant, roots and all, as soon as you spot it — the earlier the better, before whitefly spread it further.

Carry it out of the field and burn it, bury it or feed the stems to animals — never leave it lying in or beside the crop, and never take cuttings from it.

Fill the gap it leaves only if the crop is still young; late in the season, just let the canopy close over the space.

Use a fertiliser that carries potassium (K) — the nutrient cassava needs most. Your recommendation gives the type and amount for your field and soil, and may include a little zinc, which cassava also responds to on poor, sandy land.

Band it in a line about a hand's width to the side of the plants, not touching the stems, and cover it with soil so it doesn't wash or blow away.

Apply on moist soil — after a weeding or a light rain — so it dissolves down to the roots.

Go easy on nitrogen — a little is fine, but heavy nitrogen grows a big leafy bush and fewer, smaller roots.

Every 2 weeks or so, walk the field and check the growing tips and leaves — you are mainly watching, not working, now.

Green mite / mealybug: in dry spells, look for yellow speckling, bunched 'candlestick' tips and white cottony clusters near the top. Leave the helper insects to deal with light attacks.

Late brown-streak (CBSD): yellowing along the veins and brown streaks on the stems — mark and rogue, because the hidden root rot forms in these last months.

Root rot: in low, wet patches, watch for plants that suddenly wilt or yellow and stems that loosen — a sign the roots are rotting in waterlogged soil.

Scrape a little soil from a stem base now and then to feel a root — it tells you how bulking is coming along and when maturity is near.

Walk the field about once a month and simply pull or slash the few weeds that break through the canopy — mostly along the edges and in any thin spots.

Hoe shallow or hand-pull near the plants so you don't wound the swelling roots just under the surface.

Pull weeds before they set seed — stopping seed now saves you far more work next season.

Harvest when the plant shows it is ready — lower leaves yellow and drop, the soil cracks and heaves around the stem base, and a test-lift of one plant shows fat, firm roots.

About 2–3 weeks before you lift, cut the tops off at roughly knee height — this hardens the roots, slows how fast they spoil after harvest, and gives you clean stems to save.

Loosen the soil all around the plant first with a hoe or fork, especially in dry, hard ground — never just yank the plant out.

Grip the plant low, at the stem base, and rock it gently to ease the whole root bundle out in one piece.

Handle the roots like eggs — don't bruise, cut or break them; wounds turn the flesh bad fast. Lay them gently in the shade, not thrown in a heap in the sun.

Lift only what you can process or sell within 1–2 days — the rest keeps best left in the ground until you need it.

As you harvest, pick stems from your healthiest, best-yielding plants — good roots and clean leaves, with no mosaic mottling or brown streaks.

Keep the mature, brown woody middle of the stem; you can leave them long (whole stems) and cut them into stakes only at planting time.

Bundle them and stand them upright in a cool, shady spot, base down, out of the sun — standing stems stay alive and fresh far longer than stems lying in a heap.

Use the saved stems within a few weeks to a couple of months — the fresher the stem, the stronger it sprouts. Keep them off the sun and off wet ground.

Know your type first. Sweet cassava (low cyanide) is safe with normal peeling and thorough cooking. Bitter cassava (high cyanide) must go through every step below — never eat it just boiled.

Peel the roots — the skin and the layer just under it hold most of the cyanide, so take it right off.

Grate or pound the peeled root. Breaking the flesh open lets the plant's own enzyme reach and break down the poison — whole chunks trap it inside.

Soak and/or ferment the mash in water for 2–5 days, and/or press out the liquid — the cyanide dissolves into the water and escapes into the air. Pour the soaking water away safely, well away from people and animals.

Dry it slowly in the sun (and/or roast, as for gari) until hard and dry, then pound into flour or make gari/fufu — drying and cooking finish off the last of the cyanide.

Do all this within 1–2 days of lifting — spoiled roots are wasted roots. Sweet types you will eat soon can simply be peeled and cooked well.