How to Grow Runner Beans
Not only are runner beans easy to grow, but they are also interesting plants to grow in the garden due to their attractive scarlet flowers that bloom for several months during the harvesting season: July to October.
The plants grow spectacularly quickly—nearly an inch (2 cm) a day when the conditions are right. Because of this, I like to start them off growing in containers on my windowsill, so that I can come out each morning and marvel at the amount they have grown since I went to bed.
I will tell you below the secret of how to grow runner beans, where you should plant them, how to stake them, how to care for them and how to harvest and store them, with some useful tips along the way.
Where to Plant Runner Beans
Runner beans originate from South America, where they are perennials. But in colder climates, they are half-hardy annuals and need protection from frost. Therefore, they should not be planted outside until late April or May, and should be covered if frost is forecast.
They prefer full sun, but will tolerate partial shade. They should be protected from strong winds. So growing them near a wall or fence makes sense.
Before you start your bean patch, you need to dig the soil well, preferably down to the depth of your spade. Then add well-rotted organic matter or mulch, which helps to retain moisture and feed the beans. They like well-drained soil, but are quite thirsty plants and need to be watered twice a week in dry weather, especially when the flowers and beans are forming.
As beans grow so tall, you need to make sure that you grow them in a place that does not cause too much shade to other plants which need sun.
Runner Beans Need to Be Supported by Stakes
Because of their vigorous growing habit, runner beans are good as starter plants for children, who are always impatient to see results. Many types will grow to over 6 feet (2 metres) tall, so you need support canes which are at least 8 feet tall.
To make a wigwam, use four or five bamboo poles or canes 8–10 feet high, and place them approximately in a square, about 18 inches (45 cm) apart. Poke the bottom thick ends in the ground, and tie the four upper ends together with string or garden wire—so that they stand firm and are able to support the plants without falling over. If you have several wigwams in a row, you can run a cane along the tops of the wigwams and tie it in to give extra strength to the supports.
Sometimes, I just use a single cane and place it about 1 foot (30 cm) away from a fence. Then I just lean the cane towards the fence, and tie it to the fence so that it doesn't fall down, which might snap the delicate bean stems (see photograph above).
- If you wrap some garden twine around the stakes, this will help the bean tendrils to grip as they grow upwards. You could also grow beans up against mesh or netting that is attached to a tall fence.
- In order to avoid damaging the plants, it is a good idea to have the stakes in place before you plant the beans. I have myself lost good bean plants by doing it the other way round!
How to Cultivate Your Green Beans
- Plant the large seeds about 1/2 inch below the surface and cover them: in 3-inch plant pots indoors in April, in potting compost, or outdoors from late April to May.
- As beans (and peas) need a long root run, any plant pots need to be fairly tall—or you can even use the biodegradable cardboard inserts from toilet rolls. That way, when you replant them, they suffer as little disturbance to their roots as possible. Some people like to plant two seeds close together in case one fails to germinate. Then if they both come up, they can be thinned out by removing one. Or, allow them both to grow, and they can become intertwined and look like one very bushy plant.
- Keep the plant pots well watered, and they should germinate within about a week or 10 days. I have often seen beans germinate in two days and grow to be about 6 inches tall within 10 days.
- Continue to keep the bean plants well watered, and give them a feed from time to time with plant food or organic matter. A tip I have picked up but not actually tried is to make a little dent next to the plant, and pour the water into the hole instead of directly on the plant. This will ensure that the water reaches the roots rather than just the surface earth.
- When the beans have reached the top of the stakes, remove the top growing tip, so that the plant uses its strength to grow bushy and make flowers and beans, rather than continuing to grow upwards.
Pick Beans When They Are Young and Tender
Keep an eye on the brilliant red flowers, which will come out in late June or early July. Soon enough, when you look carefully through the lush green leaves, you will see pendant beans peeping below them.
Sometimes they are not immediately noticeable. If you are growing beans for the first time, you need to keep a lookout, because beans are better picked when they are young and tender.
If you can see the beans bulging in their pods, this means they are likely to be past their best. So you need to go by the texture, rather than the size of the beans.
Harvesting Encourages Heavier Cropping
Never mind if you are eating green beans with your breakfast egg, packing beans for your children's lunch boxes and drinking bean tea with your runner bean Chinese stir-fry. You can always freeze them, give them away or swap them with a friendly gardener for something more exotic.
Keep Picking the Beans and More Flowers Will Develop
As long as you keep picking them, more flowers will develop, but if you allow the bean pods to develop into longer, bigger and fatter beans in the hopes of growing monsters, you'll be disappointed. They will instead become hard and stringy, and no one will want to eat them.
Not only that, but if you allow the beans to develop big seeds, the plant will think that no more flower production is required, because it's done its job by producing ripe seeds for a future generation. So it will be a lot less prolific than a plant whose beans are regularly harvested.
Plant More Than You Need
Plant more seeds than the number you actually need, because runner bean plants are prone to mishaps, like getting snapped off or getting eaten by pests.
Slugs love them, and even birds or squirrels can cause damage to your precious seedlings.
Store Beans for Future Eating and Sowing
Beans will keep for up to a week in your fridge. If you plan to freeze them, it's best to do so immediately after picking.
And don't forget to allow one or two bean pods to mature on the bean plant, so that you can grow some more beans next year. Leave them on the plant until you can see the beans bulging inside the pods—that means they are mature.
Make sure you allow the beans that you have harvested for seeds to dry out before storing them, or they will go mildewy. I discovered at the beginning of April that my own beans were damp and had mildew on them, but planted them anyway. They all failed to germinate. Lesson learned.
Is Crop Rotation Necessary?
Traditional gardeners use crop rotation—not planting the same type of plant in the same place every year—to prevent the build up of disease and using up the nutrients in the soil. Peas, French beans, runner beans and other legumes, however, do not need to be rotated and can be grown in the same plot for several years without problem.
On the other hand, some people like to rotate their bean plants, because legumes store nitrogen in their roots and these nutrients are beneficial to other plants
Do you make your own compost?
A Useful Manual on Growing Vegetable in Pots
I love the Royal Horticultural Society books, and have two of their reference books which I use a lot. This one is Winner of the Practical Book of the Year 2013 at the UK Garden Media Guild Awards, so comes highly recommended
This content is accurate and true to the best of the author’s knowledge and is not meant to substitute for formal and individualized advice from a qualified professional.
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© 2011 Diana Grant