Growing French Beans in Scotland: The Complete Guide

Phaseolus vulgaris

Everything you need to grow French beans in Scotland, from a late-April indoor sowing to picking slender pods in August. We have done the research so you don't have to.

French beans are frost-tender. That one fact governs everything about growing them in Scotland. They need warm soil, they need the frost to be gone, and they will not forgive a cold start. Dwarf varieties are the safer choice. Eight to ten weeks from sowing to picking fits neatly inside a short summer. But a climbing variety on a sunny wigwam, planted once the soil has genuinely warmed, will crop from mid-summer into October and give you more beans from less ground. The decision is whether you want safety or yield. The honest answer is that a row of each costs little more than picking one.

Dwarf or climbing

The type decision settles everything downstream, because the two are different enough to change when you harvest and for how long.

• Dwarf beans reach about 45cm tall and need no support. They crop in 8 to 10 weeks, which is fast enough to slot into a short Scottish summer with room to spare. But they only crop for a few weeks, so you need repeat sowings. A short row every three weeks from late spring to mid-summer gives you a steady supply. In a container, allow 30cm across and 45cm deep; dwarf beans are shallow-rooted but they resent drying out.
• Climbing beans reach 2m and need tall, sturdy supports. They take longer to start cropping but then produce over a much longer period, from mid-summer into early autumn. One wigwam of a climbing variety gives you more beans from a smaller footprint than a row of dwarfs, and it keeps going for months rather than weeks.

If you only have the space for one type, dwarf beans are the lower-risk choice. If you have room for supports and the patience to wait for the soil to warm, a climbing variety earns its footprint.

Varieties

Dwarf varieties suit a short season; climbing varieties give more beans over a longer period from the same footprint. These carry the RHS Award of Garden Merit, a UK-wide award rather than a Scottish one.

Also worth considering

Soil, site and supports

French beans want a warm, sunny site with well-drained soil. Dig in at least two bucketfuls of garden compost or well-rotted manure per square metre a few weeks before planting.

Put the supports in before you plant. For climbing beans, use 2.5m bamboo canes or hazel poles. A wigwam of four or five canes tied at the top works well and looks good in a border. Space the canes 15cm apart at the base. An X-frame with canes crossing in the middle makes picking easier and usually crops better. Plant one bean at the base of each cane.

For dwarf beans, insert short twiggy sticks between the plants to keep them upright and lift the pods off the soil.

Sowing and planting

Sow indoors from late April for an early start. Sow one bean per small pot, 5cm deep, in moist peat-free multipurpose compost. Keep in a propagator or on a warm sunny windowsill. Plant out once all risk of frost has passed, usually late May or early June in Scotland.

Sow outdoors after the last frost, from late May or early June. Sow seeds 5cm deep. For climbing beans, sow one or two seeds at the base of each cane and thin to the strongest. For dwarf beans, sow 15cm apart in blocks or double rows. Warming the soil with fleece for a few weeks before sowing helps germination.

Containers: dwarf beans grow well in pots 30 to 45cm wide. Sow 5cm deep and 15cm apart. They will trail over the sides. Climbing beans need a container at least 75cm wide and 45cm deep, heavy enough not to topple once the beans are up their supports.

Watering and feeding

French beans are thirsty once they start to flower and form pods. Water regularly during dry weather. A mulch of garden compost around the plants holds moisture and keeps the weeds down. Plants in the ground rarely need feeding. Feed container plants every fortnight with a high potassium liquid fertiliser once the first flowers appear.

With climbing varieties, tie in any loose shoots and pinch out the growing tips once the plants reach the top of their supports. This encourages side-shoots lower down and keeps the crop within reach.

Harvesting

Dwarf beans are ready 8 to 10 weeks after sowing. Climbing beans start a little later but crop for much longer. Pick the pods at 15 to 20cm long. They are ready when they snap easily and before you can see the individual beans through the pod. Regular picking stimulates more flowers and more pods. A plant that is picked clean keeps producing. One left with pods swelling to seed shuts down, and the crop is over. Every two or three days is the right rhythm once they start. In a wet Scottish August that also gets you through the plants often enough to spot slug damage before it costs you a row.

French bean flowers are self-pollinating, so saved seed grows true to type. Leave a few pods to mature and dry at the end of the season, then store the seeds in a labelled paper bag somewhere cool and dry for next year. Once the crop is finished, cut the plants down and dig the roots in. As legumes they fix nitrogen that the next crop will use.

Common problems

• Slugs and snails go for young plants. Sowing indoors keeps seedlings safe until they are large enough to cope.
• Black bean aphid (blackfly) colonises the shoot tips. Pinch out affected tips and squash them, or spray off with water. The plants usually grow through it.
• Bean seed fly. Maggots that damage germinating seeds. More of a problem in cold wet soil, which is another reason to wait for warmth before sowing outdoors.
• Rust. Brown pustules on the leaves. Usually disfiguring rather than fatal. Good spacing and airflow reduce the risk.
• Nothing coming up. The soil was too cold. Wait for warmth.

Common questions

Sources