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Home & garden.

16 August 2021

How to grow French beans

Chose between climbing French beans or dwarf ones for delicious summer crops. Discover our best french bean varieties and tips for how to grow them.
CT
Ceri Thomas
French beans

 French beans are easy to grow from seed. Plant them outside once the danger of frost has passed in late spring.


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How to grow French beans: month by month

January
February
March
April
May
June



SOW
SOW/PLANT
SOW/PLANT
July
August
September
October
November
December
HARVEST
HARVEST
HARVEST



Best French bean varieties

Which? members can log in now to see the full results and which are our Best Buy varieties. If you’re not a member, join Which? to get instant access.

Best Buy dwarf French beans
What it looks like
Variety name
Yield per plant
265g
Producing almost 6kg of fine, round beans from a 2.5m double row, this was the best-performing green bean. We started picking in mid-July, and the bulk of the crop came in mid to late August, with little drop-off in overall quality until the end of the trial in late September. Being an open-pollinated variety, it will breed true, so you can save seeds for use the following year.
What it looks like
Variety name
Yield per plant
278g
A yellow-podded variety, RHS-AGM holder and previous Best Buy, this gave us the largest yield in our trial. The pale golden pods developed from white flowers, with the first beans ready to pick around a week later than others. The bulk of the yield came during August, including a bumper crop of 2.2kg from just one picking at the end of the month. By the end of September, the quality dropped slightly, with some beans becoming rather curly.
What it looks like
Variety name
Yield per plant
248g
This new variety took a little longer to get going than some others on test, but by late August, it was producing masses of deep-purple, almost black beans from attractive purple flowers (sadly the beans turn green when cooked). It’s a ‘daisy’ variety, so the pods are held above the foliage, which should make picking easier, although we found that their fineness hindered this. That said, it produced a good crop in a short time period, and since beans freeze well they would be a good choice for bulk freezing.
Best Buy climbing French beans
What it looks like
Variety name
Yield per plant
1.4g
This was one of the earliest varieties to start cropping and gave us a bumper yield of good-quality uniform beans from July onwards. The cross-section of the beans is heart-shaped, rather than round. While not as sweet as others, they have a pleasant flavour and aren’t stringy. The flowers are white and the plant isn’t very bushy, which makes it easy to spot the beans when picking.
What it looks like
Variety name
Yield per plant
1.4kg
This grew into attractive plants with dark-green leaves and purple flowers. At harvest time, the open structure of the stems made finding the beans a breeze. We got a great harvest of dark purple beans throughout the summer. The purple colour of the beans is retained better when lightly steamed or stir fried. The pods are stringless, with a very pleasant flavour.
What it looks like
Variety name
Yield per plant
1.4g
In our last test of climbing beans, this variety gave the largest yield over its long cropping season – and it impressed this time too, retaining its Best Buy status. We harvested beans for a total of 87 days. The beans have a pale green, round pod with a firm, crisp texture and taste sweeter than others. The plants have attractive mauve flowers, and it’s not too much of a faff to collect the beans.
What it looks like
Variety name
Yield per plant
1.6kg
This started cropping early, in mid-July, and continued to give uniform beans into early October. It gave the largest yield of climbing beans, almost as much as our Best Buy runner bean. It’s not very bushy, so it was fairly easy to harvest the beans. These wide, flat beans look like runner beans but are paler green. They’re not as stringy as runner beans and, though they have a mild, pleasant flavour, aren’t particularly sweet.

How we test French beans

We grew French beans and recorded when the first flowers appeared on each of our varieties. And once they started to produce beans, we picked weekly, weighing the beans and assessing them for quality. We also rated how easy the beans were to pick.

When to sow

Avoiding gluts of beans

Beans produce plentiful crops so to avoid being overwhelmed, the trick is to grow just the right amount of plants for your needs. In the Which? Gardening magazine trial, most varieties produced at least 0.5kg per plant, and our Best Buy runner-bean varieties produced up to 1kg per plant in a season. So a single wigwam of a dozen plants would be plenty for a small household.

How do climbing French beans and runner beans compare?

While climbing beans are slightly sweeter and juicier than runner beans, the real difference is that they’re not as tough or stringy. Most of the varieties we tried gave stringless, tender beans, even if they were left to grow quite big on the plant. Our Best Buys will provide a large yield, too. French/runner bean crosses don’t need pollination so are more reliable croppers than runner beans.

Indoors

French beans need warm soil and are very sensitive to frost. Start seeds in the greenhouse in late April into May, using module trays or small pots filled with Best Buy compost for sowing seeds.

Outdoors

Wait until all risk of frost has passed (late May to June) to sow direct into the ground. Sow about 1.5cm deep in double rows 15cm apart. Make successional sowings to prolong the harvest.

Caring for your plants

Creating a support for climbing beans

Use bamboo canes, at least 2.4m tall, pushed well into the ground. You'll see all kinds of imaginative structures on allotments, but when Which? Gardening trialled bean supports, we found that the best three methods were: wigwam, X-frame, and A-frame.  

A wigwam is quick and easy to put up. It also has a neat, compact shape that takes up little space. 

An X-frame is created with pairs of bamboo canes inserted at 45 degrees to the ground, crossing halfway up and tied in the middle. These are strengthened by a horizontal pole tied where the canes cross. The beans are easy to pick as they hang on the outer edge of the support. 

An A-frame is very robust, easy to erect and dismantle, and good at suppressing weeds.

Planting

Harden off plants started in the greenhouse before planting outside after the last frost (mid-May to early June, depending on where you live), allowing 15cm between plants. If a late frost is forecast after planting, protect the seedlings with a layer of horticultural fleece.

Most dwarf French beans shouldn’t need any support, but in exposed areas or if the plants seem a bit leggy, a few twiggy sticks or canes and string will do the job.

Watering 

Water well in dry periods; covering the soil with a mulch of spent mushroom compost or garden compost will help to conserve moisture and also keep weeds down.

How and when to harvest

Harvest in: July to October

Pick when beans are 10-15cm long and before they show signs of seed formation. It’s best to snip off beans with scissors or nip them between your finger and thumb; pulling the beans risks unearthing the whole plant if it's a dwarf variety. Don't leave any pods to grow old on climbing beans unless you want to save seeds. Picking regularly will encourage the plants to produce lots of beans.

If you want to save seeds, especially if you’re growing an open-pollinated variety, leave the beans on a couple of plants and allow them to dry until the beans rattle in the pods before collecting them.

Common growing problems

Yellowing plants

Planting too early when temperatures are low will cause bean plants to turn yellow and fail to thrive. The best advice is to resow at the right time and start again.

Blackfly

Blackfly is the most common pest and damages the plants by sucking their sap. Either squash these insects or spray them with an organic insecticide. 

Read more about blackfly. 

Slugs and snails

Slugs and snails can munch their way through young seedlings. Pick off any you find and protect plants with organic slug pellets.   

Read more about slugs and snails.

Birds

Prevent birds, particularly pigeons, from pecking plants with a covering of garden netting or fleece.  

Read more about birds.

Alternaria

Alternaria is a fungal infection that causes leaf spots, and thrives in the mild wet weather. Remove any affected leaves.