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Runner beans are one of the most popular “grow your own” options as they are high yielding and relatively easy to look after. They produce attractive flowers which will enhance your garden through the summer months and will provide a harvest of home grown runner beans will be fresher and tastier that anything you can buy in your local supermarket!
Most of us lead busy lives and things don’t always go to plan. So, if you have been meaning to start off your runner beans for a while now but haven’t yet got round to it, you may be worried that you have left it too late.
Runner bean seeds can be planted in the UK up until early July. This should then provide a crop of runner beans from early September through to the first frosts of autumn. After early July it is considered too late to plant runner bean seeds in the UK.
Read on to discover more about runner bean growing timelines in the UK and find out how to maximise your runner bean harvest right through until the end of the growing season!
Should I Sow Runner Beans From Seed or Buy Seedlings?
Runner beans can either be grown directly from seed or bought from garden centres as established seedlings and grown on from there.
A packet of runner bean seeds will typically cost a few pounds. If you are short on time then it is quicker to buy already established seedlings but this will work out to be more expensive. That said, if you are late in the season you may have difficulty finding seedlings on sale so this may not be an option.
Shop for runner bean seeds on Amazon below:
Timeline: Growing Runner Beans From Seed
Growing timelines across all different varieties of runner beans are broadly the same.
May is the earliest month you can plant runner bean seeds indoors (or in a greenhouse). Once sown, seeds will usually take around 7 days to germinate and will have grown to a large enough size to be planted out after around 2 weeks.
Runner beans are very susceptible to frost. The lightest frost can kill a plant. So you need to make sure that the last frost has passed before planting outside (this is normally from late May onwards). Early in the season, it is best to harden them off first (by putting them out during the day and bringing them back in overnight) before permanently planting them outside.
If you are behind schedule, the latest date that you can plant seeds and still enjoy a runner bean crop will be around early July. You will then be looking at between 6 and 8 weeks of growth before they start flowering and setting pods, taking you to early September. You should then be able to harvest runner beans throughout September and even into October, weather permitting of course.
| Plant runner bean seeds | Indoors or outdoors? | Harvest from |
| Early May | Sow indoors only. Move outdoors after frost risk has passed. | Early July onwards |
| From late May (after frost risk passed) | Indoors or outdoors | Late July onwards |
| Early to late June | Indoors or outdoors | Early to late August onwards |
| Early July | Indoors or outdoors | Early September onwards |
How Long Will Runner Beans Keep Cropping?
It is usual for runner beans to crop for around 2 months on average.
Late runner beans will keep cropping up until the first frost. But as the days get shorter and temperatures start to drop you will see an inevitable fall off in the rate of growth. Things will start to slow down and will be very much dependent on the weather – if you are lucky enough to get a warm autumn with no frost then you may still be harvesting beans right through to October.
Growing Runner Beans Later in the Season – How to Minimise Risk
As time will not be on your side when you are growing late runner beans you will want to do everything in your power to minimise the chance of anything going wrong! Here we will look at four easy steps that you can take to reduce the risk of some common runner bean problems so that you can achieve the best possible harvest in the growing time that is left!
1. Start seedlings off indoors
By initially starting off seeds indoors you can minimise the risk of a failed seed germination. Starting off seeds indoors gives you more control over variables such as soil type, nutrition, moisture and temperature levels. Plus, you will be able to pretty much guarantee the absence of pests such as slugs and snails.
You can use seed trays, or even old yoghurt pots, filled with a general multi purpose compost (one for each seed) when starting off indoors – keep the soil moist and site the trays / pots on a bright and sunny windowsill and they should start sprouting within around 7 days. After another week they should be will be ready to plant out.
Another option would be to use a propagator.
2. Plant some spares
Even if you are starting of the seeds indoors, you are likely to get some that either just don’t germinate or do germinate but display weak growth. Plant some spares just incase you need them, you can then afford to discard any weak seedlings that may be present.
3. Optimise the growing environment
Once your seedlings are ready to plant out you will want to make sure that you give them the very best chance of survival. They will need:
– Full sun or partial shade
– A nutrient rich soil
– A Moist and freely draining soil. Water regularly and ensure that the soil doesn’t dry out – mulching will help retain moisture.
4. Minimise the risk of pests
The principal pests that you will need to be on your guard against when growing runner beans are slugs and snails, and aphids such as blackfly and greenfly.
Slugs and snails
Slugs and snails pose more of a danger when the plant is still at the seedling stage, as they can destroy the entirety of the plant very quickly. There are various methods that you can employ to help minimise the risk of damage from slugs such as manual removal, slug and snail traps, encouraging natural predators and creating a physical barrier using either eggshells or copper tape. For more detailed information, follow the link to our article on how to control slugs and snails in your garden.
Aphids: Blackfly and Greenfly
Both blackfly and greenfly will survive on the sap of a runner bean plant, draining its energy and stunting growth. They also produce a sticky secretion which can lead to the establishment and development of mould and disease on the runner bean plant. Aphids will group together on fresh growth, usually stems and on the underside of leaves. They often go hand in had with the presence of ants, which are attracted to their secretions and act as an enabler to help their spread.
If you discover an aphid infestation you will need to take steps to minimise any damage to the plant. These steps can include removing the aphids by hand, cutting off infested stems and removing infested leaves, removing (healthy) growing tips of the beans (which are especially susceptible), and spraying affected areas regularly with water. For more detailed information, follow the link to our article on how to deal with blackfly on runner beans.
Growing Runner Beans Later in the Season – How to Maximise Yields
There are also two easy steps that you can take to maximise your runner bean yield:
1. Feed regularly
If your runner beans were originally planted in a nutrient rich soil then they will not necessarily require any additional feeding. However, if you were to feed with a liquid tomato feed every 2 or 3 weeks after the plant has started flowering this will will certainly help to boost the crop.
2. Harvest beans at the right time
To maximise yields, runner beans should be picked regularly when they are soft and tender – this in turn will encourage new growth. If you bend them and they snap, they are good to be picked. Leaving beans on the plant for too long will cause them to go tough, rubbery and stringy.
What Should I do with Runner Bean Plants Once They Have Stopped Growing?
Over the growing season, nodules on the roots of runner beans become filled with nitrogen. At the end of the season, once the runner beans have finished, it is common practice in the UK to cut them down to root level and leave the root in place to slowly rot down over the winter months. This nitrogen stored in the root nodules is slowly released into to the soil and come next spring you should have beneficial nitrogen rich soil for subsequent crops.
Can Runner Beans Survive Winter in the UK?
Under very specific conditions, it is possible for runner bean plants to survive the UK winter and regrow the following year. In very mild winters, plants in a protected position may survive by being cut back above the root, left in the ground and mulched. In harsher winters they may survive if the root ball is dug up and stored to protect it from the cold before being replanted in the spring. For more information, check out our article on overwintering runner beans.
