Green bean

BeginnerRepeatedly through the seasonPlanted as seed

Phaseolus vulgaris

The most forgiving crop in the garden: push the seed in warm soil and it does the rest, feeding itself nitrogen as it goes. Bush types crop hard for a few weeks, pole types climb and keep going. Pick every two or three days and they keep setting.

Before you plant

Self-fertile — one plant sets fruit. Self-pollinating and needs no insects, which is why a bean crop sets reliably in weather that costs squash and cucumber their fruit.

Light

Full sun (6+ hours)

Full sun. Beans in shade grow leafy and set few pods.

Water

Moderate

Water steadily, and especially while the plants are flowering and filling pods. Do not water the leaves.

Soil & substrate

Any well-drained soil

Ordinary garden soil that drains well. Beans make their own nitrogen so they do not need rich ground.

Feeding

Light feeder

Almost nothing. Beans fix their own nitrogen, and a heavy feed gives you leaves instead of beans.

Training

Trellis

Depends which you grew. Bush beans need no support at all. Pole beans need something two metres tall standing before you sow, because they climb on their own and will not wait.

Harvest signs

Pick when a pod is about as thick as a pencil and snaps cleanly in half, roughly a week to ten days after the flower. Check every two or three days.

Life of the plant

Timing shifts with your frost dates — never fixed calendar days

1Germination7–10 days after sowing

Wait for warm soil. Bean seed rots rather than sprouts in cold wet ground.

2Seedling1–3 weeks after sowing

Seed leaves come up first, then the first proper leaves. A pale young bean is normal and does not need feeding.

3Vegetative14–30 days after the previous stage

The plant bushes out, or starts to climb. Stay out of the bed while the leaves are wet.

4Flowering35–45 days after sowing

Small white or violet flowers open. This is when steady water matters most.

5Fruiting1–2 weeks after the previous stage

Pods swell to full length in about a week to ten days after the flower.

6Harvest window50–105 days after sowing

Pick every two or three days. A pod left to ripen tells the plant to stop flowering.

Varieties

Bush or dwarf

Self-supporting plants about 600 mm tall that need no trellis. They crop heavily for two to three weeks then tail off, so sow a short row every two to three weeks rather than one long row.

Pole or climbing

Climbers reaching 1.8 m or more that must have a support standing before you sow. They pick over six to eight weeks from one sowing and yield more from the same ground than bush types.

Half-runner

Between the two at no more than about 900 mm. Manages without a support but crops better and stays cleaner given a short one.

Wax or yellow

Yellow-podded snap beans, grown and picked exactly like the green ones. Easier to spot among the leaves, which in practice means fewer pods missed and left to go tough.

Romano or flat-podded

Wide flat pods with a fuller flavour. They stay tender at a larger size than round-podded types, so they are more forgiving if you miss a picking.

What to watch for

What each one looks like, so you know it when you see it

Mexican bean beetlePestHigh susceptibility

Stages affected: Vegetative · Flowering · Fruiting

A leaf beetle that looks almost exactly like a large ladybird and is routinely spared because of it. Unlike true ladybirds it eats the plant rather than the pests on it, and both the adults and the spiny yellow larvae skeletonise bean leaves from the underside.

Visual signs: Adult a rounded dome about 6 to 8 mm long coppery orange to tan with sixteen black spots in three rows across the back · Spiny yellow larvae up to 8 mm long covered in soft branched black-tipped spines feeding in groups on leaf undersides · Clusters of about 40 to 60 yellow eggs standing on end on the underside of a leaf · All stages present together on the same plant from midsummer · Feeding almost always on the underside of the leaf rather than the top
Damage pattern: Leaf tissue eaten from beneath between the veins leaving a lacy skeleton that then dries brown · Damage concentrated on the lower and inner leaves first · Pods and stems scarred once the leaves are gone · Whole plants stripped and stunted in a bad year with pods failing to fill

Common bacterial blight of beanBacterial diseaseHigh susceptibility

Stages affected: Vegetative · Flowering · Fruiting · Harvest window

A seed-borne bacterium that spots and browns bean leaves and marks the pods. It arrives on infected seed and then moves through a row in water: rain splash, overhead watering, and hands and tools brushing wet plants. Nothing cures it, so it is managed by clean seed and by keeping out of the bed while the foliage is wet.

Visual signs: Water-soaked spots on leaves that enlarge into irregular brown dead patches · A narrow bright yellow border around each brown patch which is the most useful single sign · Patches running together until whole leaves look ragged and scorched at the margins · Water-soaked spots on pods that dry to sunken reddish-brown blotches · A crusty pale bacterial ooze on pods or leaf undersides in humid weather
Damage pattern: Spreads outward from a focus along the row in the direction water and hands have travelled · Follows a rainstorm or an overhead watering rather than appearing evenly · Worst on the lower leaves first then upward · Marked pods are still edible but a badly affected plant sheds its leaves and fills few pods

AphidsPestMedium susceptibility

Stages affected: Vegetative · Flowering

Small soft-bodied sap-sucking insects that cluster on the softest new growth. They reproduce extremely fast in warm weather and are the main insect vector of plant viruses in the garden.

Visual signs: Clusters of small pear-shaped insects on shoot tips buds and leaf undersides · A pair of short tubes (cornicles) projecting back from the rear end, which is the deciding feature · Green yellow brown red or black depending on species, wingless or winged · Curled twisted or yellowing new leaves and stunted shoots · Sticky honeydew on the leaves below, often turning black with sooty mould · White cast skins left on leaves and easily mistaken for live insects · Ants running up and down the stems
Damage pattern: Concentrated on the newest softest growth and worst on heavily fed plants · Honeydew and sooty mould appear below the colony rather than at it · Virus symptoms such as mottling yellowing and distorted growth may follow long after the aphids have gone

CutwormsPestMedium susceptibility

Stages affected: Germination · Seedling

The caterpillars of several drab night-flying moths. They live at the soil surface and chew through the stems of young plants at ground level, so you almost always find the damage before you find the caterpillar.

Visual signs: Smooth dull caterpillar up to 40 mm long in grey brown or near black often with faint stripes · Curls tightly into a C shape the moment it is touched or uncovered · Found 25 to 50 mm down in loose soil within a hand's width of the damaged plant · Nothing visible on the plants by day because they feed after dark
Damage pattern: A young plant cut clean through at soil level and left lying beside its own stump · Whole seedlings gone overnight with the root still in the ground · Ragged holes chewed in the leaves that rest on the soil · Damage running along a stretch of row rather than scattered across the bed

White moldFungal diseaseMedium susceptibility

Stages affected: Flowering · Fruiting

A soil fungus with an enormous host range that rots stems at the soil line and collapses the plant. It attacks more than 300 species including beans cabbage potato tomato and lettuce, and its hard black resting bodies survive in the ground for five to eight years, so where it appears it becomes a long-term feature of that bed. On lettuce the same fungus is usually called lettuce drop.

Visual signs: Water-soaked patches on the stem at or just above the soil line that spread quickly · Dense white cottony growth over the affected stem or pod looking like cotton wool rather than dust or fuzz · Hard black lumps the size and shape of rodent droppings forming in and on that white growth · Stems above the lesion bleached pale and dried out · Whole plant or one branch wilting and collapsing while the rest looks well
Damage pattern: Starts at the soil line or wherever a dead flower or leaf has fallen and lodged in the canopy · Collapses individual plants rather than sweeping across a bed · Worst in a dense canopy after a wet spell during flowering · Recurs in the same patches of ground year after year

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