French Beans

Start from seed: October-January

Optimum soil temperature for germination: 16-30°C

Plant spacing: 15-25 cm (dwarf varieties), 15-30 cm (climbing varieties)

Days to maturity: 50-70 days

Introduction

French beans (Phaseolus vulgaris), also known as green beans, snap beans, or string beans, are annual legumes belonging to the Fabaceae family. They come in two main growth habits: bush (dwarf) varieties that grow to about 45 cm in height, and climbing varieties, also known as pole beans, that can grow 2-3 metres tall with proper support.

Originally native to Central and South America, beans have been cultivated for thousands of years. Archaeological evidence of bean cultivation dates back to at least 7,000 years ago in Peru and Mexico. European explorers brought beans back from the Americas in the 16th century, and they quickly became a staple food crop across Europe and eventually worldwide.

French beans are prized for their tender, flavourful pods, which are harvested while still immature before the seeds fully develop. They are nutritionally rich, providing good amounts of vitamins A, C, and K, folate, and fibre. Beans are a legume which makes them very valuable in the garden due to their ability to fix atmospheric nitrogen in the soil via a symbiotic relationship with beneficial bacteria.

Site and soil

French beans thrive in Canberra when planted in a sunny, sheltered position that receives at least 6-8 hours of direct sunlight daily. Protection from strong winds is important as bean plants can be easily damaged, especially when laden with pods. Ensure climbing beans are situated in a position that will not cast shade over other crops.

Prepare the soil by incorporating plenty of compost or well-rotted manure and complete organic fertiliser. French beans prefer a fertile, well-drained soil with a pH between 6.0 and 7.0. They perform best in a neutral soil pH; if your soil is acidic, add lime to raise the pH level. Beans, being nitrogen fixers, actually improve soil fertility, making them excellent to include in rotations.

For container growing, use pots at least 30 cm deep with good drainage. Fill with premium potting mix boosted with compost and complete organic fertiliser. Container growing works particularly well for dwarf varieties but can also accommodate climbing types if adequate support is provided.

For details on preparing soil and pots, including the use of lime, dolomite, gypsum and fertilizers, please refer to the COGS guide to garden bed preparation.

Planting Seeds and Seedlings

French beans should be sown after all danger of frost has passed, typically from mid-October to early November. Soil temperature should be consistently above 16°C for successful germination.

Sow seeds directly into the garden to a depth twice the size of the seed. For bush beans, Sow bush bean seeds 5-10 cm apart in rows 25-30cm apart, and thin to 15-25cm apart once seedlings are established. For climbing varieties, sow seeds 5-10 cm apart in rows far enough apart to allow harvesting from both sides of the trellis or supporting structure. Thin to 15-30cm spacing. Alternatively, climbing beans can be sown in clusters of 3-4 seeds around each support pole in a teepee formation.

French beans can be raised as seedlings 3-4 weeks before the last frost for transplanting later. However, they prefer direct sowing as they don’t always transplant well due to their delicate root systems. It is far more cost effective to sow bean seed than to purchase seedlings.

After planting, water thoroughly but gently to avoid disturbing the seeds. Apply a light mulch either before or after seedlings emerge to retain moisture and suppress weeds. Later ensure that the mulch is kept away from the stems to prevent rot.

Cultivation

Consistent moisture is crucial during germination and pod development. Water regularly to maintain evenly moist (not wet) soil, particularly during flowering and pod formation. Bean plants have shallow roots, so be careful when weeding to avoid root damage.

While beans can fix their own nitrogen from the atmosphere, they benefit from a complete organic fertiliser at planting time. Avoid high-nitrogen fertilisers, which can promote lush foliage at the expense of pod production. A potassium-rich fertilizer applied when flowering begins can help boost pod development. A monthly foliar spray with seaweed solution; a mix of worm juice, seaweed and compost tea; or trace elements will help boost growth and resilience to pests and diseases.

Climbing varieties need sturdy support structures at least 2 meters tall. Traditional options include bamboo teepees, trellises, or netting attached to a sturdy frame. Gridded galvanised sheep panel mesh attached to star pickets works well and will last for many years. Install supports prior to planting to avoid disturbing roots later.

Bush beans generally don’t need support but may benefit from light staking in exposed areas to prevent wind damage. Some gardeners use low brush fencing or twiggy branches to provide light support for dwarf varieties.

Keep the growing area weed-free while plants are young and in the establishment phase. Once there is canopy cover, weeds will be less of a problem.

Harvesting

French beans are typically ready to harvest 50-70 days after sowing, depending on the variety and growing conditions. Harvest pods when they are young and tender, before the seeds inside become too pronounced. The optimal size depends on the variety, but generally, pods should be firm, crisp, and snap easily when bent.

For best quality, harvest in the morning when plants are turgid. Use two hands to pick – hold the stem with one hand while pulling the bean with the other to avoid damaging the plant. Regular harvesting encourages continued production so pick beans every 2-3 days once they begin to form.

Bush beans tend to produce their crop over a shorter period compared to climbing varieties that produce over a longer season, up to 2 months. For a continuous harvest throughout summer, sow successive crops every 2-3 weeks until early January.

Store harvested beans in the refrigerator in a container or plastic bag for up to one week. Beans are prone to cold damage. The ideal storage temperature for beans is around 10⁰C which is warmer than the average fridge. To extend the shelf life try to keep them at the ideal temperature or in the warmest part of the fridge. For longer storage, beans can be blanched and frozen, or preserved by pickling or drying.

Problems

The best approach is to have a reliable Australian reference book to identify problems. Garden Pests, Disease and Good Bugs by Denis Crawford is recommended.

A general strategy to follow with any problem is to observe the plant carefully before taking action. Identify the problem then carefully consider the course of action. For example, with pest insects, you often can see a predator nearby. If you watch and wait the predator may deal with the problem for you. Beneficial predatory insects which feed on pest insects can be purchased from suppliers such as Bugs for Bugs. If the problem needs further action the above recommended book has suggestions.

Practicing good garden hygiene, crop rotation, and maintaining plant vigour by providing adequate nutrients are key strategies for prevention.

French beans can encounter several pests and diseases in Canberra gardens:

Slugs and Snails: These are particularly problematic for young seedlings. Control methods include beer traps, copper tape barriers, organic snail baits (iron EDTA), or evening patrols to manually remove them.

Aphids: These small sap-sucking insects can transmit celery mosaic virus. They often cluster on the undersides of leaves, causing distortion and stunting. Small populations can be controlled by washing them off with a strong stream of water or using insecticidal soap. Alternatively, neem oil or pyrethrin can be used. Beneficial predators like ladybugs and lacewings should be encouraged and can be purchased for release on the crop. Look for aphid mummies which are evidence that the aphid has been parasitised. Eggs can also be parasitised and will appear bronze in colour. Generally speaking, plants that are high in soluble nitrogen (nitrates and ammonia) are prone to attack by sap sucking insects. Ideally avoid using soluble nitrogen fertilisers and ensure plants have adequate trace elements. This can be achieved by using foliar sprays.

Bean summer death: serious viral disease caused by tobacco yellow dwarf virus transmitted by the common brown leafhopper. Plants look wilted and stunted. They will suddenly collapse and die. If your plants are well watered, mulched and protected from wind yet display these symptoms sudden death is the most likely culprit. The presence of this virus can be confirmed by pulling out a plant then slicing through the lower stem. Healthy tissue will be green whereas diseased tissue will be dark, almost black. Infected roots may be black and rotten. Prevent by selecting resistant varieties and controlling leaf hoppers.

Bean Fly: The larvae tunnel into stems, causing wilting and plant death. Prevention through crop rotation and covering young seedlings with row covers until flowering can help reduce damage.

Common Blight: A bacterial disease-causing water-soaked spots on leaves that later turn brown with yellow margins. Prevent by using disease-free seed, avoiding overhead watering, and practicing crop rotation.

Rust: A fungal disease appearing as rusty brown pustules on leaves. More common in humid conditions. Control by ensuring good air circulation, avoiding overhead watering, and removing affected leaves promptly.

Halo Blight: A bacterial disease characterized by small water-soaked spots surrounded by a yellow halo. Use disease-free seed and practice crop rotation to prevent occurrence.

Root Rot: Various fungi can cause rotting of roots, particularly in poorly drained soil. Ensure good drainage and avoid overwatering to prevent this condition.

Recommended Varieties

There are numerous varieties to choose from. If you plant several successions, it is an opportunity to grow a few different varieties.

Dwarf (Bush) Varieties:

Jackson – Outstanding quality. An improved French bush bean with round, glossy, dark green pods to 15cm with great flavour. Very productive. Intermediate resistance to Summer Death AKA Bean Yellow Mosaic Virus
Baby Sun 108 – fast maturing, slender, classic baby French bean, tender and tasty. Very productive.
Jade – Strong upright bushes, fine quality pods to 13cm, some disease resistance.
Simba -round, dark green bush bean with fantastic flavour. Heavy cropper with good disease resistance. Its heavy frame keeps the beans straight and clean as they are held well off the soil.
Gourmet Delight- Prolific producer of tender, stringless pods; disease resistant.
Purple King – Distinctive purple pods that turn green when cooked; heat tolerant.
Bountiful – Early maturing with flat green pods; reliable producer.
Royal Burgundy – Purple pods with good disease resistance; performs well in cooler soil.

Climbing Varieties:

Heavenly Gold – highly productive, flat, yellow pods bearing over a long period. Pods stay tender even when large.
Blue Lake – Classic variety with round, stringless pods; excellent flavour and disease resistance.
Scarlet Runner – Ornamental red flowers followed by long, flat pods; good cold tolerance.
Cherokee Wax – Yellow, butter beans with excellent flavour; heavy yielder.
Borlotto Lingua di Fuoco – Italian variety with beautiful red-streaked pods; can be used fresh or dried.

References

Bubel, Nancy. The New Seed-Starters Handbook. Rodale Books, 2018.
Crawford D. Garden Pests, Disease and Good Bugs. Australia: ABC Books; 2015.
Dove, Helena. Botany of the Kitchen Garden, Kew Publishing, Royal Botanic Gardens Kew, UK, 2023.
Fanton, Michel and Jude. The Seed Savers Handbook. The Seed Savers Network, Australia, 1993.
Gardenate. (2024). Growing Beans – dwarf in Australia – temperate climate. https://www.gardenate.com/plant/Beans+-+dwarf?zone=2
Yates Australia. (2024). How to Grow Beans. https://www.yates.com.au/how-to-grow/beans/