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Phaseolus vulgaris

Common bean

Fabaceae

Mexico, Central America and the Andes

Attracts Pollinators Container Friendly

Native to North America

SunFull Sun

WaterMedium

Overview

Phaseolus vulgaris is a frost-tender annual legume carrying two growth habits within one species: bush forms 18-24 inches (45-60 cm) tall that flower across a concentrated 2-3 weeks, and pole forms twining to 6-10 feet (1.8-3 m) that crop for 6-8 weeks. Leaves are alternate and trifoliate, the terminal leaflet 3-6 inches (8-15 cm) long, ovate with a drawn-out tip. Pea-type flowers 0.4-0.6 inch (10-15 mm) long open in short axillary racemes in white, pink or violet, and self-pollinate inside the bud, so home-saved seed comes true. Pods run 4-8 inches (10-20 cm) long, round or flat in section, green, yellow or purple, holding 4-8 seeds; purple pods turn green during cooking. Roots carry Rhizobium spp. nodules that fix atmospheric nitrogen and meet most of the crop own demand, though little residual nitrogen remains once pods and tops are taken away. Raw and undercooked dry seed contains phytohaemagglutinin, a lectin that causes vomiting and diarrhoea; boiling for 10 minutes breaks it down. Seed rots rather than germinating in soil below 60F (16C), flowers drop above 90F (32C), and halo blight, anthracnose and bean common mosaic virus all carry over on saved seed.

Native Range

Phaseolus vulgaris was domesticated twice from wild populations ranging from Mexico to Argentina, giving a Mesoamerican gene pool of small-seeded types and an Andean pool of large-seeded types. Wild forms with shattering pods still grow on mid-elevation slopes from Jalisco south through the Andes. The species reached Europe after 1500 and is now grown across temperate and tropical agriculture.

Suggested Uses

Grown in vegetable beds and raised beds, bush types at 4 inch (10 cm) spacing in rows and pole types on tripods, netting or a 6-8 foot (1.8-2.4 m) trellis. Pole cultivars are used as a summer screen along boundary fences and as the climbing element of three-sisters plantings with corn and squash. Bush types crop in containers of 5 gallons (19 litres) holding three plants each.

How to Identify

Recognised by trifoliate leaves with a swollen pulvinus at the base of each leaflet, which lets the leaflets fold and track through the day. Pole types twine around a support without tendrils, which separates them from peas and vetches. Pods hang in pairs or small clusters from the leaf axils with a persistent thread-like style at the tip, and each seed carries a white eye-shaped hilum along one edge.

Appearance

Size & Dimensions

Height1'6" - 10'

Width/Spread1' - 1'6"

Colors

Flower Colors

Foliage Colors

Bloom Information

Bloom Period

~8 weeks

Summer Fall

Bush cultivars flower 45-55 days after sowing over a concentrated 2-3 week window, so most pods reach picking size within about 10 days of each other. Pole cultivars start flowering 60-70 days after sowing and continue 6-8 weeks while pods are picked young. Flowers self-pollinate inside the closed bud, so insect activity has no bearing on pod set. Flowering spans July and August in temperate gardens, with a further flush through September on pole types.

Detailed Descriptions

Flower Description

white, pink or violet

Foliage Description

medium green, with purple-flushed veins on purple-podded cultivars

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-10 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range6.0 - 7.0(Neutral)

357912

Soil Types

loam sand silt

Drainagewell drained

Water & Climate

Water Needs

Medium

Care & Maintenance

Care Guide

Grows in full sun with 6-8 hours of direct light in free-draining soil at pH 6.0-7.0. Seed is sown direct 1-1.5 inches (2.5-4 cm) deep once soil holds 60F (16C), at 4 inch (10 cm) spacing for bush types in rows 18-24 inches (45-60 cm) apart, or 6 inches (15 cm) apart around a 6-8 foot (1.8-2.4 m) support for pole types. Water use runs about 1 inch (25 mm) per week and rises through flowering and pod fill, applied at soil level because wet foliage spreads bacterial blight. Nitrogen feeding stays low since the root nodules supply the crop, with phosphorus and potassium worked in before sowing to cover the rest of the demand. Mexican bean beetle skeletonises leaves from the underside and spider mites build up during hot dry spells. Pods picked every 2-3 days at pencil thickness hold the plant in flower, while seed left to swell inside a pod shuts down further bloom.

Pruning

No pruning is carried out on bush cultivars of Phaseolus vulgaris. Pole cultivars are stopped at the top of their support, usually 6-8 feet (1.8-2.4 m), which turns growth into lateral flowering shoots. Spent plants are cut at soil level after cropping so the nitrogen-bearing root nodules break down in place.