VegetablelegumeStraightforward

French bean

Phaseolus vulgaris

A frost-tender bean that will not tolerate cold soil, which makes sowing date the whole decision: too early and the seed rots, too late and the crop runs out of season. Dwarf cultivars need no support and crop in a rush; climbing ones need a structure and crop steadily for months from a much smaller area of ground.

Position: Full sun
Water: moderate demand
Drainage: Moisture-retentive, Free-draining
Grows to: 40–200 cm × 25–40 cm
Hardiness: H2
Harvest: July to October
Difficulty: Straightforward

Described view

A dwarf French bean plant in a container carrying straight green pods held clear of the compost

August

Harvest

French bean’s year

Resolved for United Kingdom (general). Every window is stored against a climate event rather than a date, so a late frost pocket runs later than the band shows. What else August calls for.

Activity	M	A	M	J	J	A	S	O
Sow under cover	March.	April.
Sow outdoors			May.	June.	July.
Harvest					July.	August.	September.	October.

Names that cause confusion

haricot — The same species, left on the plant until the seeds mature and dry. Dried haricot, cannellini, borlotti and kidney beans are all Phaseolus vulgaris.

Timing that travels

The band above resolves this plant's windows into months for one region. These are the windows themselves, stored against a climate event rather than a date — which is the form that survives being carried to a colder garden, a frost pocket, or next year.

Sow under cover
2–4 weeks before your last spring frost
source
Sourced guidancehigh confidence
- Royal Horticultural Society: French beans — sowing
Checked 2026-08-13
For an earlier start. Beans dislike root disturbance, so sow into deep modules or pots.
Sow outdoors
0–8 weeks after the soil warming, successionally, every three weeks until midsummer
source
Sourced guidancehigh confidence
- Royal Horticultural Society: French beans — sowing outdoors
Checked 2026-08-13
Wait for warm soil rather than a date. Sowing into cold ground wastes the seed.

Conditions it needs

Light: Full sun
Direct sun: 6 hours a day or more
Frost: Frost tender
Hardiness rating: H2 (RHS)
Grows best at: 18–25 °C
Germinates at: 16–30 °C
Soil: Loam, Sandy, Silt
Soil pH: 6–7
Drainage: Moisture-retentive, Free-draining
Water needs: moderate
Drought: moderate tolerance
Waterlogging: poor tolerance
Heat: good tolerance
Wind and exposure: poor tolerance

Where these figures come from

LightSourced guidancehigh confidence

Royal Horticultural Society: French beans — position

Checked 2026-08-13

Direct sunHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

FrostSourced guidancehigh confidence

Royal Horticultural Society: French beans — hardiness

Checked 2026-08-13

Hardiness ratingSourced guidancehigh confidence

Royal Horticultural Society: RHS hardiness ratings

Checked 2026-08-13

Grows best atHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Germinates atSourced guidancehigh confidence

Seed rots rather than germinates in soil below about 12 °C, which is the commonest reason an early sowing fails to appear.

OSU Extension Service — Oregon State University: Vegetable seed germination temperatures

Checked 2026-08-13

SoilHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Soil pHSourced guidancehigh confidence

University of Minnesota Extension — University of Minnesota: Soil pH for vegetable crops

Checked 2026-08-13

DrainageHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Water needsHorticultural consensusmoderate confidence

Water most from flowering onwards; drought at that point costs pods directly.

No external citation — see the evidence type above.

Checked 2026-08-13

DroughtHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

WaterloggingHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

HeatHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Wind and exposureHorticultural consensusmoderate confidence

Climbing cultivars on a wigwam are vulnerable in wind.

No external citation — see the evidence type above.

Checked 2026-08-13

On your soil

Computed by comparing this plant's recorded requirements against each soil's recorded characteristics. A recorded horticultural fact overrides the comparison where GrowingHQ holds one.

Soil	Verdict	Why
Heavy clay	Works, with one condition	French bean will crop on heavy clay, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Sandy	Prefers this soil	Sandy suits French bean as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. Sandy soil is among the soils it is recorded as suiting.
Chalky and alkaline	Works, with one condition	French bean will crop on chalky and alkaline, but one thing has to be dealt with first. The soil is substantially too alkaline for it: it wants pH 6 to 7, and this soil sits around 7.8 to 8.5.The pH is the obstacle. Small shifts are achievable and slow; large ones are not. On chalky and alkaline the dependable answer is a container of the right compost rather than an attempt to change the ground.
Loam	Prefers this soil	Loam suits French bean as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering.
Silty	Prefers this soil	Silty suits French bean as it stands: The pH suits it: it wants 6 to 7, and this soil is in that range. The free drainage is exactly what it wants. Silt is among the soils it is recorded as suiting. The soil holds moisture, which saves a great deal of watering.
Peaty and acid	Works, with one condition	French bean will crop on peaty and acid, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.
Shallow over rock	Prefers this soil	Shallow over rock suits French bean as it stands: The free drainage is exactly what it wants. Loam is among the soils it is recorded as suiting.
Made ground and urban soil	Works, with one condition	French bean will crop on made ground and urban soil, but one thing has to be dealt with first. It needs ground that drains, and this soil holds water. For a crop lifted before winter the risk is not rot but the season: waterlogged ground is cold and unworkable in spring, so sowing is late and germination patchy.Improve the drainage before planting — a raised bed, or bulky organic matter worked in over several seasons. Do not add sand to clay in small quantities; it makes the problem worse.

Not sure which you have? Four hand tests will settle it.

Space and spacing

Mature height: 40–200 cmSourced guidanceDepends on conditions
Mature spread: 25–40 cm
Rooting depth: 45 cm
Spacing: 15–20 cm apart
Row spacing: 45–60 cm

Where these figures come from

Mature heightSourced guidanceDepends on conditionshigh confidence

Applies when: Dwarf cultivars reach 40–50 cm; climbing cultivars reach 2 m and need a support built for them.

Royal Horticultural Society: French beans — cultivars

Checked 2026-08-13

Mature spreadHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Rooting depthHorticultural consensusmoderate confidence

USU Extension — Utah State University: Vegetable rooting depths

Checked 2026-08-13

SpacingSourced guidancehigh confidence

Royal Horticultural Society: French beans — spacing

Checked 2026-08-13

Row spacingSourced guidancehigh confidence

Royal Horticultural Society: French beans — spacing

Checked 2026-08-13

Measured centre to centre. Plants set closer than this compete for light and water long before they look crowded, and the crowding cannot be undone once they are in.

In a container

Minimum volume: 15–20 litres
Minimum depth: 25 cm

Where the container figures come from

Minimum volumeSourced guidancehigh confidence: Royal Horticultural Society: Beans in containers
Checked 2026-08-13
Minimum depthHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

Dwarf cultivars are among the best legumes for a container: no support, quick, and productive for their size.

Where and how you can grow it

Each way of growing is assessed separately, and “not assessed” is a real answer rather than a gap we have filled in with a guess.

Method	Suitability	What it needs
Open ground	Well suited source Sourced guidancehigh confidence Royal Horticultural Society: French beans Checked 2026-08-13
Traditional dug bed	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Raised bed	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Container	Well suited source Sourced guidancehigh confidence Royal Horticultural Society: Beans in containers Checked 2026-08-13	A dwarf cultivar; 15 litres or more
Polytunnel	Well suited source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13	Extends the season at both ends and helps in cold districts.
Vertical growing	Workable source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13	A climbing cultivar and a structure that carries the weight
Greenhouse	Workable source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13
Hydroponics	Workable source GrowingHQ editorial positionmoderate confidence Grows well and gives up its main advantage doing so. A bean fixes atmospheric nitrogen through root nodules and is therefore the crop least in need of a nitrogen solution, so a system is spending its running cost on something the plant already had. GrowingHQ editorial synthesis — GrowingHQ Checked 2026-08-13
Windowsill	Marginal source Horticultural consensusmoderate confidence A dwarf cultivar on a very bright sill will crop lightly. No external citation — see the evidence type above. Checked 2026-08-13

Growing it

SowingSow 5 cm deep into warm soil. If the soil is below about 12 °C, wait — a fortnight's patience produces a better crop than a fortnight's head start with rotted seed.5 cm
SupportClimbing cultivars need canes, netting or strings to 2 m, put up before sowing. Dwarf cultivars need nothing, though a few twigs stop the lowest pods lying on the soil.
HarvestingPick every two or three days while the pods snap cleanly. A plant carrying maturing seed stops producing new flowers, so consistent picking is what keeps a climbing cultivar going into autumn.
ProtectionFrench beans are frost-tender annuals and are not overwintered. Cover a late crop with fleece if an early frost threatens and it will often go on cropping into October. When the plants finish, cut the tops off at ground level and leave the roots in the soil — the nitrogen-fixing nodules on them are worth more to next year's crop than the space is, and pulling the whole plant up removes them.

Where this guidance comes from

SowingSourced guidancehigh confidence: Royal Horticultural Society: French beans — sowing
Checked 2026-08-13
SupportHorticultural consensusmoderate confidence: Royal Horticultural Society: French beans — supporting
Checked 2026-08-13
HarvestingSourced guidancehigh confidence: Royal Horticultural Society: French beans — harvesting
Checked 2026-08-13
ProtectionSourced guidancehigh confidence: Garden Organic — Garden Organic (Henry Doubleday Research Association): Legumes and soil nitrogen
Checked 2026-08-13

Is it worth putting under cover?

Whether it will grow there is on the methods table above. This is whether the space is well spent, which is a different question and usually the one being asked.

Structure	What protection is worth	What decides it
Greenhouse	Extends the season source GrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file. GrowingHQ editorial synthesis — GrowingHQ Checked 2026-08-13	Frost dates. A protected sowing crops several weeks before the outdoor one and is finished before the space is needed for anything else.Unlike its runner-bean relative, a French bean is self-pollinating and sets perfectly well in a closed house.
Polytunnel	Extends the season source GrowingHQ editorial positionmoderate confidence What protection is worth for this crop, judged against the same standard as every other record in this file. GrowingHQ editorial synthesis — GrowingHQ Checked 2026-08-13	Frost dates.

Growing it without soil

Nearly anything can be grown in a soilless system by somebody with enough equipment. The useful question is whether it is worth it, in which technique, and what goes wrong.

Works with conditions

Succeeds when the conditions listed here are met and fails when they are not. The conditions are the answer, not a caveat.

source

GrowingHQ editorial positionmoderate confidence

Grows well and gives up its main advantage doing so. A bean fixes atmospheric nitrogen through root nodules and is therefore the crop least in need of a nitrogen solution, so a system is spending its running cost on something the plant already had.

GrowingHQ editorial synthesis — GrowingHQ

Checked 2026-08-13

Techniques that suit it

Drip-fed mediumSolution is dripped into an inert medium around each plant. The most forgiving technique and the one that suits large, long-season, heavy crops.
Ebb and flowA bed of inert medium floods and drains on a timer. The medium holds moisture between floods, which makes it far more tolerant of interruption than NFT.

source

Horticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

Root space: Moderate. Dwarf types only; climbing beans need more support than most frames carry.
pH band: 5.5–6.5

Where these figures come from

Root spaceHorticultural consensusmoderate confidence

No external citation — see the evidence type above.

Checked 2026-08-13

pH bandSourced guidancehigh confidence

Outside roughly this band, individual nutrients become unavailable even when they are present in the solution — which is why a crop can starve in a full reservoir.

Purdue Extension — Purdue University: Hydroponic solution management — pH

Checked 2026-08-13

What actually goes wrong

Pump or power failure. In nutrient film and aeroponics there is no reserve at the roots, so a crop can be lost within hours; medium-based systems hold moisture and are far more forgiving.
source
Sourced guidancehigh confidence
- Purdue Extension — Purdue University: Hydroponic system design — failure modes
Checked 2026-08-13
Warm solution. Above roughly 22 °C the water holds much less dissolved oxygen and root disease follows quickly, which is why summer is harder than winter in an indoor system.
source
Sourced guidancemoderate confidence
- Purdue Extension — Purdue University: Solution temperature and dissolved oxygen
Checked 2026-08-13

No nutrient recipes here

GrowingHQ records pH bands, which are measurable properties of nutrient availability, and deliberately records no EC or PPM targets and no mixing instructions. Published targets vary by cultivar, growth stage, water source and technique, and the figures that apply to your system are on the product you bought.

Harvesting

Time from sowing or planting: 8–12 weeks

source

Sourced guidancehigh confidence

Royal Horticultural Society: French beans — timing

Checked 2026-08-13

When it is readyPick young, while the pod snaps rather than bends and before the seeds show as bumps along it.
How to pick itPinch or snip the stalk; pulling tears the brittle stems.
Keeping itFreezes well after blanching. Pods left to mature and dry on the plant become haricot beans for storing.

Where the harvest guidance comes from

When it is readySourced guidancehigh confidence: Royal Horticultural Society: French beans — harvesting
Checked 2026-08-13
How to pick itHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13
Keeping itHorticultural consensusmoderate confidence: No external citation — see the evidence type above.
Checked 2026-08-13

Keep picking

Regular picking keeps this plant producing. Fruit or leaves left to mature signal it to slow down or stop.

What goes wrong

Problem	How often	Notes
Pea and bean weevil	occasional source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13	Less often than on peas and broad beans, because French beans go out into warm soil and grow away fast.
Slugs and snails	common source Sourced guidancehigh confidence Royal Horticultural Society: Slugs and snails Checked 2026-08-13	Seedlings are very vulnerable for the first fortnight.
Aphids	occasional source Horticultural consensusmoderate confidence No external citation — see the evidence type above. Checked 2026-08-13

Grown with, grown after, grown instead

Every relationship states its mechanism. A pairing nobody can explain is a pairing nobody has checked, and it does not go in.

Closely relatedRunner bean
Different species in the same genus, grown almost identically. The practical differences are that runner beans depend on insect pollination to set pods and tolerate cooler conditions, while French beans are self-pollinating and need more warmth.
source
Sourced guidancehigh confidence
Royal Horticultural Society: Beans
Checked 2026-08-13
Same rotation groupPea
Both Fabaceae, sharing the legume rotation slot and its root diseases.
source
Horticultural consensusmoderate confidence
Royal Horticultural Society: Crop rotation
Checked 2026-08-13

Safety and edibility

Preparation
Dried beans of Phaseolus vulgaris — including home-dried haricot and borlotti, and kidney beans above all — contain phytohaemagglutinin, which causes severe vomiting and diarrhoea if they are eaten raw or undercooked. Slow, low-temperature cooking without a proper boil does not destroy it and can concentrate the effect.
source
Sourced guidancehigh confidence
- Home and Garden Information Center — Clemson Cooperative Extension: Dry bean safety
Checked 2026-08-13
Soak dried beans, discard the soaking water, and boil vigorously for at least ten minutes before any longer simmering or slow cooking. Green pods picked and cooked normally are not affected.

Sources for this page

Garden Organic · GrowingHQ editorial synthesis · Home and Garden Information Center · OSU Extension Service · Royal Horticultural Society · University of Minnesota Extension · USU Extension

Each figure on this page carries its own citation, under the “where these figures come from” note in its section. Record last reviewed 2026-08-13.