How to grow French beans

A huge range of varieties, of both dwarf and climbing, are readily available as seed in garden centres and from online retailers.

If you don’t have the time or space to grow from seed, young plants can also be bought from garden centres and online suppliers in spring and early summer, ready for planting outside. However, the choice of varieties may be fairly limited.

For an early crop, sow indoors in late April to early May. Use small pots or trays of deep modules, sowing one bean in each, 5cm (2in) deep. Place in a propagator or on a warm, sunny windowsill to germinate. They will grow fast in warm, bright conditions and need watering regularly.

In late May or early June, harden off the young plants to acclimatise them to outdoor conditions. Then plant into their final site, after all risk of frost has passed – see Planting out, below.

Before sowing, prepare your ground carefully and put supports in place for climbing varieties – see above.

French beans can be sown outdoors once all risk of frost has passed and the soil is warming up – usually in late May or early June, depending on your local climate. Warming the soil with fleece or cloches for a few weeks before sowing can aid germination, and if left in place they’ll also give the seedlings extra protection.

Sow the seeds individually, 5cm (2in) deep and 15cm (6in) apart. With climbing beans, sow one or two at the base of each bamboo cane, then thin out the seedlings if necessary to leave the strongest one.

Dwarf beans are best sown in blocks or double rows, so they support each other. Sow a few extra at the end of the rows to fill any gaps if some seeds don’t germinate. You can also sow these through weed-suppressing membrane to reduce the need for weeding and prevent the pods being damaged by contact with the soil.

To provide harvests over a longer period, make several sowings of dwarf beans from late spring right through to late summer.

You can sow seeds outdoors in spring into pots of multi-purpose compost – either in small pots for transplanting into the ground later, or large containers as their final growing site.

Sow one bean per small pot, 5cm (2in) deep, then place in a cold frame or a warm, sheltered position, protected with fleece. Once the plants reach 8cm (3in) tall and all risk of frost has passed, plant out into their final positions (see Planting outside, below).

Both dwarf and climbing beans can be grown in large containers and make attractive additions to patios and small gardens. They need a warm, sheltered, sunny position. For dwarf beans the container should be 30–45cm (12–18in) wide, and for climbing beans 75cm (30in) wide, 45cm (18in) deep and heavy enough to keep it from toppling over once the climbing beans are at the top of their supports.

For climbing beans, insert a wigwam of 2.5m (8ft) canes (see Putting up supports, above) into the container before sowing. Dwarf beans don’t usually need support and look great cascading over the sides of a pot or even in a hanging basket.

Then simply sow the seeds into the container of potting compost, 5cm (2in) deep and 15cm (6in) apart. With climbing beans, you can sow one or two seeds at the base of each cane, then thin out the seedlings if necessary to leave the strongest one.

Place a mulch of well-rotted manure or mushroom compost around plants in July to help hold moisture in the soil.

Keep the growing site weed-free. Consider planting through slits in weed-suppressing membrane – this reduces the need for weeding and prevents the pods of dwarf beans being damaged by contact with the soil.

French bean flowers are self-pollinating, so plants grown from saved seeds are likely to be true to type. At the end of the cropping season, leave a few pods to fully mature, then pick once dried. Remove the seeds from the pods, then store in a labelled paper bag somewhere cool and dry over winter, to sow the following spring.