How to grow common bean

Pick a field where you have not grown beans, peas, groundnuts or other legumes for 2–3 years — many bean diseases survive in the soil and on old bean trash. Land that grew maize or another cereal last is a good choice.

Choose land that drains well — beans hate wet feet and rot quickly where water sits after rain. Avoid the low, soggy corners of the field.

Clear out and dig in old bean stalks and pods from earlier crops; don't leave them lying around, as they carry disease straight into the new crop.

Plan your planting date so the crop flowers in cool weather. Count forward: beans flower about 4–6 weeks after planting, and flowers drop when days go above 30 °C or nights above 20 °C — so don't plant so that flowering lands in the hottest, driest spell.

Only lime if your soil is sour — a soil test says so, or past crops on that land stayed small, yellow and stunted even when you fed them. Your recommendation gives the amount for your field.

Spread the lime evenly over the whole field, like sprinkling flour by hand — patches give you patchy beans.

Work it into the topsoil with a hoe or plough. Lime only sweetens the soil it is mixed into; left lying on top it does almost nothing.

Do it 2 weeks to 2 months before planting — lime is slow, so late liming won't help this crop. Put the phosphorus (P) on with the lime, because P is exactly what the sweetened soil now lets the roots reach.

Buy certified bean seed from a registered dealer — a sealed, labelled bag with the variety name and this season's packing date. Certified seed is graded free of the seed-borne diseases that ordinary grain-beans carry.

Choose the habit that suits you: bush beans are quick and need no stakes; climbing beans yield far more but need stakes and a longer season. Ask the dealer or check your recommendation.

Buy only a little basal fertiliser — a small starter of nitrogen plus phosphorus (P) (a compound fertiliser, or DAP — di-ammonium phosphate), just the amount in your recommendation. Beans fix their own nitrogen, so they need far less than a cereal like maize — don't over-buy nitrogen.

Where bean fly bites hard, ask for insecticide-dressed seed (or a seed dressing) — it guards the seedling through the first few dangerous weeks.

Store seed and fertiliser dry, off the floor, away from food, water and children. Keep the label and receipt in case the seed turns out poor.

If you are growing climbing beans, collect one strong 2–3 m stake per hill — straight poles, tall grass stems or cut branches all work.

No stakes to spare? Set up strings or a trellis instead: firm posts at the row ends with lines run between them for the vines to climb.

Have them ready before planting, so you can stake the moment the vines begin to twine (about 15–20 days after planting), before they flop onto the ground.

Bush beans need no stakes — skip this if that is what you planted.

Use only well-rotted manure or compost — dark, crumbly, no strong smell. Fresh, strawy manure needs more time to break down first.

Spread it evenly over the field — about a wheelbarrow every few strides is a good rate.

Work it into the topsoil 1–2 weeks before planting, so it settles in with the soil before the seed goes down.

Plant into moist soil — a real planting rain that wets the ground a hand deep — so the seeds come up together and evenly.

Open your holes at the right spacing for your habit: bush beans about 50 cm between rows and 10 cm along the row (a hand-width apart); climbing beans about 60 cm between rows and 20 cm along the row (two hand-widths apart).

Drop two seeds per hole, about 5–7 cm deep — a finger pushed in to the second knuckle. A little deeper in dry, sandy soil; shallower in heavy, wet soil.

Put the basal (the little starter of nitrogen + phosphorus) in the hole beside the seed, with a pinch of soil between the fertiliser and the seed so they don't touch and burn the sprout. Use dressed seed in bean-fly areas.

Cover and firm the soil over seed and basal, so the seed sits snugly in moist earth and comes up strongly.

Walk the crop twice a week from the day it comes up, looking closely at young seedlings across the whole field — not just the edge by the path.

Bean fly: look for seedlings that yellow, wilt and stay small, with the stem base swollen or cracked; split a dying stem and you'll find a tiny maggot or brown tunnel inside. Act if you see 3–5 dying plants close together, or 3–4 small black flies to a stride-square (m²), around the 2–3-leaf stage — open the bean-fly guide.

Damping-off: look for seedlings that flop over and rot at the soil line, often in wet patches. Improve drainage and don't replant into the same soggy spot.

Mosaic virus (BCMV — bean common mosaic virus): look for leaves that are mottled yellow-and-green, puckered or curled. Pull out and remove badly-affected plants so aphids don't spread it further.

Count the gaps (holes with no plant) as you walk, so you know whether to gap-fill.

About 7–12 days after planting, once the seedlings are up, walk the rows and count how many plants came up against the number of holes you sowed.

Work out the share that came up — for example, 85 plants from 100 holes = 85%.

85% or more → a good stand, carry on.

Below 85% → gap-fill the biggest gaps in the next few days, while the soil is still moist and the crop is only days old (re-sow two seeds per empty hole).

If it fails (gaps stay empty and the stand is thin): re-sow the gaps at once, and if a whole patch failed, work out why — bean fly, rot, poor seed or a hard crust — before it happens again.

About 10–14 days after planting (the seedlings now have a few true leaves), draw a little loose soil up around the base of each stem with your hoe, like a small mound.

Cover the swollen, damaged part of the stem base — new roots will grow from the buried stem, above where the maggot fed.

Do it gently so you don't cut the shallow roots or bury the growing tip.

Keep the topsoil moist but not wet — check by pushing a finger in, and water when it's dry a finger-deep.

Water every 5–7 days, more often in heat and on sandy soils that dry fast.

Water gently at the base, not a hard flood — beans are easily waterlogged, and standing water rots the young roots.

Walk the crop twice a week, turning over leaves and checking the growing tips across the whole field.

Aphids / whitefly: look for clusters of tiny green or black insects on shoot tips and leaf undersides, sticky leaves, or little white flies that puff up when you shake a plant. They spread virus — knock off or treat the hot-spots early.

Angular leaf spot: look for grey-brown, straight-edged (angular) patches boxed in by the leaf veins, with fine grey mould underneath.

Bean rust: look for rusty, reddish-brown powdery pustules that rub off onto your finger.

Root rot: look for plants that yellow and wilt in wet patches; pull one and the roots are brown and rotten. Improve drainage — don't waterlog.

Give the crop its first weeding early, about 2 weeks after planting (around day 15), before the weeds get bigger than the beans.

Hoe shallowly — beans root close to the surface, and deep hoeing near the plants cuts those roots.

Do the second weeding about 2 weeks after the first (around day 30 after planting) to keep the field clean right through the critical first month.

In dry areas, leave the pulled weeds lying between the rows as a mulch to hold moisture.

Watch for the vines starting to twine and reach out — usually about 15–20 days after planting.

Give each hill one strong 2–3 m stake, pushed in firmly beside the plants, or run string/trellis lines between end-posts.

Guide the young vines onto the stake or string once — after that they climb on their own.

Do it before the vines flop onto the soil; a sprawling vine sets far fewer pods and rots on the ground.

Water when the soil is dry a hand-width down (deeper than at seedling stage — the roots have grown).

Water every 7–12 days, depending on heat and soil.

Don't let the crop wilt during this fast-growth stage, but don't waterlog it either — beans rot in soggy soil.

Walk the crop twice a week, but only when the leaves are dry — bacteria spread on wet hands and tools.

Bacterial blight: look for water-soaked spots on leaves and pods that dry to brown, sometimes ringed by a yellow halo.

Bean rust: look for rusty reddish-brown pustules on the leaves that dust your finger.

Heat flower-drop: look for flowers falling off without setting pods after hot days or warm nights — a sign the weather is above the crop's limit.

Check the flowers and tiny pods for caterpillars or holes as the first pods set.

Keep the soil evenly moist right through flowering — check often and don't let it dry out.

Water every 5–7 days, more often in heat.

Never let the crop wilt at flowering, even for a day — wilting now costs you flowers and pods.

Water in the cool of the morning or evening, gently at the base, so you don't waste it or splash disease onto the leaves.

Walk the crop twice a week through pod-fill, checking flowers and young pods on plants across the field.

Look for small caterpillars on flowers and pods, round entry holes in the pods, and droppings (frass) where a pod joins its stalk.

Open a few suspect pods to see if the seeds inside are eaten.

Treat only if it's worth it — many pods attacked across the field, not just the odd one. Spray while the caterpillars are still outside the pods.

If you must spray: cover your skin, eyes and nose, spray in the cool of the day with the wind behind you, keep it off any pods you'll eat soon, respect the pre-harvest interval on the label (the number of days you must wait between the last spray and eating or selling the pods), and wash afterwards.

Keep the soil moist through pod-fill — check often, and don't let a dry spell in.

Water every 5–7 days, more in heat.

For dry beans, keep watering while the pods are filling and green, then stop about 20–25 days before harvest so the crop dries down evenly.

For green/snap beans, keep watering right up to the last pick — you're picking pods, not drying them.

Start picking when the pods are full-length but still flat and crisp and snap cleanly when bent — before the seeds bulge through the pod.

Pick gently, holding the stem so you don't tear the plant, taking every ready pod.

Come back every 6–8 days and pick again — 3–4 pickings over about 20–30 days. Regular picking keeps new pods coming.

Keep watering right up to each pick, and get the pods to shade and market quickly — they don't keep.

Harvest when the crop is mature and dry: leaves yellow and drop, pods turn straw or tan, dry and rattle, and the seeds are hard — you can't dent one with a thumbnail.

If it's not there yet (leaves still green, pods still leathery, or a seed dents under your thumbnail): don't cut — leave the crop standing and check again in a few days, so the seed finishes filling and hardens for storage.

If you irrigate, stop watering about 20–25 days before so the crop dries down evenly.

Cut or uproot the whole plants in the cool of the morning — fewer pods shatter than when they're bone-dry and brittle in the midday sun.

Lay or stack the plants to dry fully on a tarp or clean surface for a few days — never on bare soil.

Thresh the dry pods (beat them in a sack or with a stick) and winnow out the chaff in the wind, leaving clean grain.

Dry the threshed grain (or whole dry pods) on a tarp, mat or raised rack — never on bare ground, which pushes damp back in and adds soil, stones and animal dirt.

Spread it thinly in the sun and turn it regularly so it dries evenly; cover it or bring it in if rain threatens.

Dry to about 12–14% (lower for long storage). Bite test: a seed is dry enough when it cracks rather than dents between your teeth.

If it still dents (too wet): dry it more before storing — damp beans mould and feed weevils.

First make sure the grain is fully dry — a seed cracks, not dents, when bitten. Damp grain spoils even when sealed.

Sort out any already-holed, spotted or damaged seed — holed seed hides live weevils that would breed on inside, and seed with dark, sunken brown-to-black spots is carrying anthracnose, a seed-borne disease.

Seal the clean, dry grain in airtight containers: PICS triple bags (three-layer airtight bags — tie each layer), or sealed drums or bottles filled to the top with little air.

Sealed tight, the oxygen runs out and the weevils die, even beans that were infested in the field — and it needs no chemicals.

Low-cost extras that help: mix wood ash through the grain to clog the weevils, or spread the beans in the hot sun before sealing.