French beans are the crop that flatters a beginner. One seed the size of a fingernail, pushed into warm soil in the last week of May, becomes a plant that feeds a household for two months and asks for almost nothing in return. They are also the crop most often lost before it ever emerges — not to pests or disease, but to impatience. Phaseolus vulgaris is a tropical American plant with no frost tolerance whatsoever and a firm dislike of cold, wet ground, and a row sown in April will simply rot where it lies.
This guide is the hub for the whole genus: what separates dwarf from climbing, why runner beans are a different species that behaves differently, how deep and how far apart to sow, and how to pick so the plants keep producing. Written in late September, it comes at the wrong end of the season on purpose — the last pods are coming off the canes now, which is exactly the moment to note what worked and order seed for next May while the memory is fresh. For what to do with the pods you leave to swell, see drying beans for winter.
- Sow Mid-May to early July outdoors, once the soil holds 15 °C — or indoors from late April
- Depth & spacing 5 cm deep · dwarf 15 cm apart in rows 45 cm apart · climbing 2 seeds per cane
- Germination 7–14 days at 18–25 °C; below about 12 °C the seed usually rots instead
- Harvest 8–10 weeks from sowing, then every 2–3 days until the first frost
Dwarf, climbing and runner: three plants, two species
Everything sold as a French, dwarf, bush, snap, filet or borlotti bean is Phaseolus vulgaris, and the difference between the forms is one gene for climbing. Dwarf beans make a knee-high bush, crop heavily for three or four weeks and then stop — which makes them the ideal candidate for succession sowing, a short row every three weeks from late May to early July. Climbing French beans run to two metres, take a fortnight longer to start and then crop steadily until the frost, from a quarter of the ground area. If you have room for only one, grow the climbers.
Runner beans are a different species — Phaseolus coccineus — and the distinction matters in practice, not just on the label. Runners are perennial at the root, have scarlet or white flowers that need insects to set, and sulk in hot dry weather when the pollen fails and the flowers drop without forming pods. French beans are self-pollinating, so they set fruit in a heatwave when runners will not. Runners are also marginally hardier at the start and stringier at the end. Broad beans are not beans at all in this sense but vetches, Vicia faba, sown in autumn or very early spring — the opposite calendar entirely, covered in growing broad beans from seed.
Within P. vulgaris the choice is mostly about when you pick rather than how you grow. Green or wax beans are picked immature, pod and all. Flageolet types are left until the seeds swell but the pod is still soft, then shelled fresh. Borlotti and haricot types are left until the pod turns papery and the beans inside are hard and dry. Many varieties will do all three if you let them, which is why one row can feed you twice.
When to sow — soil temperature, not the calendar
A bean seed needs the soil at about 15 °C to germinate reliably, and it will sit and rot in anything much under 12 °C. In most of the UK that means the third week of May outdoors, a fortnight later in the north or on heavy clay, and up to a fortnight earlier in a mild southern garden or under cloches. The date on the packet is a national average; the thermometer in your own bed is the real instruction, and pushing a cheap soil thermometer in at 8 am for three mornings running will tell you more than any calendar. The principle applies across the tender crops — see how to germinate seeds for the mechanics of warmth, water and air.
You can steal two or three weeks by starting indoors in late April, one seed to a 9 cm pot or a deep module, and planting out after the last frost once the plants have their first pair of true leaves. Beans resent root disturbance, so do not let them get pot-bound, and do harden them off properly — a bean moved straight from a windowsill to an exposed bed will stall for a fortnight. Sowing can carry on until the first week of July; anything later will flower but rarely fills its pods before the nights cool. Beyond that, the June sowing list and the May list show what else goes in alongside them.
One old trick is worth ignoring: soaking beans overnight before sowing. It speeds nothing up meaningfully and swollen seed coats split and admit rot. Sow them dry, water the drill well first, and then leave the bed alone until the shoots appear.
Sowing beans, step by step
- Prepare the ground in advance Beans want soil that holds moisture but drains — a barrowload of compost dug in, or spread on top, a few weeks before sowing. Skip the nitrogen feed; see preparing your soil. Choose a sheltered, sunny spot, because two metres of climbing bean in full leaf catches wind like a sail.
- Put the supports up first For climbers, build the wigwam or double row of 2.4 m canes before you sow, not after — driving canes through a root system is how you lose plants. Two seeds at the foot of each cane, thinned to the stronger one. Supports and trellising covers the structures in detail.
- Sow 5 cm deep into warm, watered soil Draw a drill, water the bottom of it, then space dwarf beans 15 cm apart in rows 45 cm apart. Cover and firm gently. Sow a few spares at the end of the row to fill gaps. This is classic direct sowing territory.
- Protect the seedlings for the first fortnight Slugs will take a whole row of bean seedlings overnight and mice will dig the seed itself out of the drill. A cloche, a cut bottle or a length of fleece over the row until the plants are 15 cm tall solves both.
- Water at flowering, and mulch Beans are indifferent to drought until the flowers open, then critically thirsty — a bucket every few days per square metre while they set pods doubles the crop. A mulch keeps that water in and the weeds down; see watering and mulching.
Dwarf or climbing? Choosing the right form
Dwarf (bush) beans
Knee-high plants, no supports, a concentrated crop.
- Ready in 8–9 weeks and finished in 3–4 — sow in short successions
- No canes, so they suit windy plots, raised beds and large containers
- Pods sit near the ground and need watching for slugs and splash
- Lower total yield per square metre, and more stooping to pick
Climbing French beans
Two metres of vine on canes, cropping for months.
- Start 10–14 days later but crop from midsummer to first frost
- Two to three times the yield from the same ground area
- Pods hang clear of the soil: cleaner, straighter, easier to spot
- Need a solid structure and a sheltered site, or the whole wigwam goes over
Both take the same soil, the same spacing within the row and the same watering. If you are short of beds, note that beans fix their own nitrogen through root nodules and leave the ground in good heart — cut the tops off at the end of the season and leave the roots in, then follow with a leafy crop. Crop rotation made simple explains where legumes sit in the cycle, and peas follow the same logic with a much earlier calendar.
Picking: green, fresh-shelled or dried
Green beans are ready when the pod snaps cleanly and the seeds inside are still barely visible as bumps — usually 8 to 10 weeks from sowing. From then on, pick every two or three days whether you need them or not. The plant is trying to make seed; every pod you leave to swell is a signal that the job is done, and cropping slows within a week. A neglected row in August can often be brought back by stripping every mature pod off and watering hard.
Leave selected pods on deliberately and you get two more harvests from the same plants. Fresh shelling beans — flageolet and young borlotti — come out of a plump but still-soft pod and cook in twenty minutes. Left another three or four weeks the pods go papery and the beans dry hard on the plant, which is the winter store: how to dry beans for winter covers the harvesting, shelling, drying and the important safety point about cooking home-dried beans properly. The same dried beans double as next year's seed, provided the variety is open-pollinated rather than F1 — heirloom, F1 and organic seed explains the difference, and seed saving covers the general method. Beans are among the easiest crops to save from because the seed dries in the pod with no wet processing at all, unlike the crops in saving pumpkin and squash seeds.
Pests and problems
Blackfly cluster on the growing tips in early summer; pinch the top 5 cm out once the plants reach the top of their canes and most of the problem goes with it. Slugs and snails are the real threat, and only at the seedling stage. Bean seed fly maggots hollow out the seed before it emerges in cold wet soil — another argument for sowing late into warm ground. Halo blight shows as small water-soaked spots with a pale ring; it is seed-borne, so pull affected plants and never save seed from them. Chocolate-brown spots and a general collapse in a wet August is usually anthracnose, treated the same way. Common garden pests and common plant diseases cover the wider picture, and companion planting has the classic sweetcorn-and-beans pairing.
Common mistakes
- Sowing too early. Cold soil rots bean seed. A row sown on 20 May overtakes one sown on 25 April, because the second one is usually sown twice.
- Feeding with a nitrogen fertiliser. Beans make their own. Extra nitrogen buys you a magnificent leafy plant with very few pods.
- Putting the canes in after the seedlings are up. The roots are wider than the plant looks, and a cane driven through them checks growth for weeks.
- Letting the picking slip. Miss a week in August and the plants switch to seed production. Pick small, pick often.
- Sowing the whole packet at once. Dwarf beans crop for a month. Three short successions beat one long row every time.
Frequently asked questions
Can I still sow French beans in September?
Not outdoors in a temperate climate — there is no longer enough warmth or day length to fill the pods before frost, and a September sowing will flower without cropping. September is for hardy things: overwintering broad beans, autumn peas, winter salads. Put the bean bed under a green manure instead and keep the seed for May.
Do beans really need bean poles, or will netting do?
Climbing French beans twine anticlockwise around anything vertical between about 1 cm and 5 cm thick — canes, string, netting, a wire mesh panel. What matters is the anchoring, not the material: a fully laden wigwam in a September gale is remarkably heavy. Tie the tops firmly and drive the feet in at least 30 cm.
Why did my beans flower but set no pods?
Almost always heat and dryness at the root during flowering, which makes the flowers drop. It is far more common in runner beans, which rely on insect pollination, than in self-fertile French beans. Water heavily from the first flower, mulch, and — for runners — mist the flowers on hot evenings.
Can I grow French beans in a container?
Dwarf varieties are excellent in pots: a 30 cm pot takes three plants, a large trough a whole row. Use a good multipurpose compost, water daily in summer and expect a slightly shorter cropping period. Container gardening from seed has the pot sizes and compost details.
A bean row is one of the few things in a vegetable garden that gives back more than it takes: a summer of pods, a winter jar of dried beans, next year's seed and a bed left richer than it was found. Note now which varieties cropped and which sulked, then browse the French bean, dwarf bean, runner bean and organic bean ranges, the wider legume and vegetable seed collections or the organic vegetables list. For the season ahead, April and May sowings are where the bean year begins, and our growing guides and the beginner's guide to growing vegetables from seed cover everything alongside them.
