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HOW TO GROW BROAD BEANS
Broad beans have been cultivated for thousands of years and the reason for this is simple, they are very nutritious, they are easy to grow and they produce a large crop for the area they occupy. The very best broad beans are those just slightly smaller than the average man's thumbnail, at this size they are sweet and tender with a thin skin.
In many areas of the UK they can be sown in open ground in autumn and this will produce an early crop in late spring or early summer. Success for autumn sowings depends on where you live in the UK and how wet / cold the winter weather is. Our guide below gives very specific advice for your area of the UK.
QUICK CALENDAR FOR GROWING BROAD BEANS
Correct timing is probably the most important factor in sowing broad beans and lumping all areas of the UK together (as most websites do) will not give you the correct sowing dates. Click here to adjust ALL dates in this website to be correct for your area of the UK and Ireland. If your area of the UK is too cold for autumn sowing it will tell you below.
Sow seeds outside in autumn - the third week of October 2017
Sow seeds in pots for spring planting - the last last week of February 2017
Sow seeds outside in spring - the last week of March 2017
Transplant pot grown plants outside - the last week of March 2017
Start to harvest Broad Beans approximately - the second week of June 2017
Depending on the height of the variety you are growing and conditions in , wind may be an important factor. It's always best to choose a site which is at least partly protected from the wind. Click here for details further down this page on how to support broad beans.
Autumn sowings are best made directly into ground in the third week of October 2017. At this time of year the soil will still be about the correct temperature for germination. The two major problems with autumn sowing are cold and water-logging. Whilst you may be able to predict the temperatures with some accuracy, the amount of rain which may fall before spring is almost impossible to predict. Water-logging will cause the seeds and seedlings to rot.
To help you decide if autumn sowing is an option in your area consider the diagram below showing average soil temperatures in the UK. The majority of areas in the UK will fall somewhere between the blue and red lines. The chart shows the average of day and night time temperatures combined and you can assume that the day time temperature is about 2°C higher than the averages shown below.
The minimum temperature at which broad beans will germinate is 7°C / 45°F. If cloches are in place, or the ground is covered in plastic, the soil temperature will be approximately 2°C higher than shown in the above diagram, the ground will also be drier reducing the risk of the seeds rotting. The soil temperature is the key to sowing broad beans in autumn. If the temperature is high enough for just a couple of hours, the seeds seeds will start the germination process.
For spacing and depths to sow broad beans see the paragraph Spring Sowing Direct in the Ground below. Although many books and gardening websites recommend autumn sowing, our experience is that in many winters the seeds fail to grow and even when they do the advantages over spring sown seed is almost indiscernible.
SPRING SOWING IN POTS
Only do this if you can provide cool (but not freezing) conditions for the seeds to germinate and grow on. If the seedlings are grown on in warm conditions the plants become leggey and very prone to damage when planted out. A cold frame or unheated greenhouse is ideal as is an unheated room or against the outside wall of a heated house out of windy conditions. Sow the seeds in the last last week of February 2017 and transplant them into open ground in the last week of March 2017.
Fill a 7cm / 3in pot with multi-purpose compost and stand in shallow water for half an hour. Use a plant marker to make a hole in the compost about 4cm / 1½ deep and drop the seed in - it's not important which way round the seed goes. Fill the top of the hole with compost and gently firm the surface of the compost down. Mark the pots with the variety sown and the date. Place the pots in a cool position (in or out of light). The ideal soil temperature for germinating broad bean seeds is about 12°C / 54°F but anywhere between 7°C / 45°F to 15°C / 59°F will give good results.
As soon as the seedlings appear above the compost make sure to move the pots to a position which gets lots of light and is also cool, a temperature around 12°C / 54°F is ideal for growing on young broad bean plants.
SPRING SOWING DIRECT IN THE GROUND
This is a good method for almost all areas of the UK. Seed should be sown in the last week of March 2017.
Sowing broad bean seeds is simple. First the ground should be well dug to allow good drainage. If the soil is poor add well-rotted compost or a couple of handfuls of blood fish and bone fertiliser to every square metre / yard.
Broad beans have a very good germination rate so it's only necessary to sow one seed for every broad bean plant wanted. Sow a couple more seeds at the end of a row just in case one or two plants don't grow.
For dwarf varieties sow seeds 15cm / 6in apart, for taller growing varieties sow 23cm / 9in apart. Sow the seeds about 6cm / 2½ins deep lightly covering the seed with soil and lightly firming it down. Water well if conditions are dry.
If you are sowing more than one row then it is theoretically possible to have the rows 23cm / 9in apart. That is fine if you limit yourself to two rows. If you are sowing more than two rows then you need to allow more space between every second row (60cm / 2ft) so that you can walk down the rows and harvest your crop.
We have a strong preference for the dwarf varieties of broad beans because they don't need any support, taller varieties do. If you need to create supports then simply set stakes into the ground along each side of the row and tie a couple of string lines along the row supported by the stakes.
Broad beans are generally easy plants to grow without any special needs. When the pods start to grow on the lower part of the plant it's a good idea to pinch out the growing tip to help the pods grow well and also to reduce the severity of any attack by aphids.
Broad beans have two methods of pollination, important to know if you grow them in a greenhouse / polytunnel or under cloches. Their primary method is self-pollination, in other words they do not need insects to produce a crop. However, they can also be pollinated by insect activity and will produce the best crop when pollinated using both methods.
So, if you provide cloche protection early in the year it's best to remove the cloches as soon as flower buds start to appear. This will allow bees and other insects to get at the flowers when they form.
HOW TO SUPPORT BROAD BEANS
Taller varieties of broad beans will need support and even some of the shorter varieties will need support in windy conditions. This is very easy to do if you follow our instructions below.
Insert a cane deep into the ground at each corner of the area where the beans are to be grown. Tie one or two rows of string around the corner posts to enclose the broad beans. This applies equally to a single row or a block of the plants. If using one row of string, place it about 60cm / 2 foot high.
Nothing stronger is required, this will be enough to provide support to stop the plants toppling over. The string / canes can be put in place at any time before the plants reach 60cm / 2 foot high. See our page on broad bean varieties here for an estimate if a particular variety will require support or not.
POLLINATION OF BROAD BEANS
Most broad beans are partially self-fertile but you will have a much better crop if insects pollinate them as well. This varies depending on the variety. We explain below how they can pollinate themselves and some problem areas.
As a broad bean flower develops, the stigma inside the flower becomes taut and it is also bent over. Insect activity in the flower will cause the stigma to spring open onto the pollen allowing fertilisation to occur. In some cases, where there is no insect activity, the stigma will ripen and spring open as a result of wind movement. Sometimes it happens and sometimes it doesn't which explains why poor pollination can occur.
Some bees have got lazy in recent years and instead of entering the flower from the front to get at the nectar, they drill a small hole at the base of the flower and get the nectar from there. This type of bee activity is not so efficient as far as pollination is concerned.
Another problem with broad bean pollination is that different varieties will easily pollinate each other if insects are allowed to go between the varieties. This will often result in pods which are not true to type.
WHEN AND HOW TO HARVEST YOUR BROAD BEANS
Broad beans are best harvested when they are young and about the size of half an average thumbnail. At this stage the beans will have soft and tender skin and the flesh will be sweet and delicious.
Many beginners who have not grown broad beans before have asked the question, "does a broad bean plant produce ore than one picking of the crop throughout the year?". The answer is they only produce one picking each year however not all the beans on a broad bean plant mature at the same time.
They ripen earliest at the bottom of the plant. The amount of pods (each pod contains 8 to 10 beans) per plant is very variable depending on the variety but around 15 to 20 pods is a an average amount.
When your broad beans have finished cropping they can be dug up and placed on the compost heap. In their place there is still time to sow some lettuce, radish and beetroots. The beetroot may not grow to full size but they are delicious when harvested young.
As a guide broad beans should be ready for harvest around the second week of June 2017 although this will depend on when the seeds were sown and the weather conditions. Autumn sown seeds will tend to be ready a couple of weeks earlier compared to spring sown seeds.
To harvest the beans, twist the pod and gently pull the stem until it is removed from the plant. This can be a bit tricky some times because the stem holding the beans to the main stem can be quite tough. Don't pull too hard, it can pull the plant out of the ground. If the stems are tough then a small pair of scissors is a very good alternative.
GROWING BROAD BEANS IN CONTAINERS
Broad beans are not an ideal vegetable to grow in containers however given the right variety and a large container they can be successful. The container should be at least 30cm / 1ft deep to allow the roots sufficient room. The best dwarf variety to choose is definitely The Sutton. Cultivation is the same as for growing in open ground although more watering will be required especially in warm and dry weather.
One trick which significantly reduces the need for constant watering is to place a layer of small stones or wood chip on the surface of the soil in the container. This works very well, far better than you might expect.
RECOMMENDED VARIETIES OF BROAD BEANS
We have dedicated an entire page to reviewing large number of broad bean varieties which can currently be grown in the UK. Click here to go there now.
PESTS AND DISEASES OF BROAD BEANS
Broad Beans are very strong growing plants and suffer from very few pests and diseases in our experience. The only pests you are likely to suffer from are aphids and this a very common occurrence. Spraying is not really an option because the beans will be harvested soon after any spraying occurs. It is worth while pinching out the growing tips as described in the care section above. The aphids love the growing tips and if you pinch them out it will remove their first point of feeding.
If aphids do attack then follow our advice in our page on aphids.
Damage to the leaves of broad bean plants is most likely due to pea / bean weevils. They tend to leave notches in the edges of the leaves. They can severely damage young broad bean plants but larger plants can normally outgrow them. See our page on vine weevil which is almost the same pest and the advice given applies to both.
Blackened tips or edges to the leaves is, in most cases caused by frost damage. Plants started off indoors and then planted out (or into an unheated greenhouse) too early without hardening them off are the most vulnerable. Normally they will grow through the damage when the weather warms up.
There is some doubt as to whether broad beans benefit much from crop rotation. We discuss this in detail on our crop rotation page which can be found here.
END OF ARTICLE
COMMENTS / QUESTIONS LEFT BY OUR READERS
|Date: 30 October 2016||From: Elizabeth T|
|QUESTION: I have grown some broad beans In my unheated greenhouse. Can I plant them out now?.
ANSWER: Yes you can. Just as a precaution I would take them out of the greenhouse for a week to fully harden them off. Put them where they will be exposed to some wind but take them back in temporarily if it gets very windy.
|Date: 7 August 2016||From: Joy|
|If there is only one advantage to an autumn sowing, it's having one less thing to do when the garden gets busy in spring.|
|Date: 23 October 2016||From: James|
|QUESTION: When you pod broad beans should they have a black line on one end?
ANSWER: Some do and some don't, it all depends on the variety. I don't have a picture of one that does but see this link here for a good picture of broad beans with a black line at the end of each bean.
|Date: 13 July 2016||From: Jan C|
|QUESTION: Why are there no beans in my broad bean pods? They are big pods and look full, but when I picked them there was only one or no beans in them. The pods were about 6 to 7" long. Any suggestions please?
ANSWER: There are a couple of reasons for this. The first is a lack of insect pollination. Sometimes the weather is too windy or cold when the flowers need pollination. There is not much you can do about this (other than hand pollination) and next year there may well be no problem.
The second reason is that the flowers have been pollinated but they have failed to set. The most common reason for this is that temperatures are too high. If you suspect this is the case, plant out / sow seeds slightly earlier next year to avoid the warm weather.
|Date: 25 March 2016||From: Jennifer Jenkin|
|I found the answers to all my questions on this website. Thanks|
|Date: 19 March 2016||From: Caroline M|
|QUESTION: I have pinched out the tops of my broad plant seedlings, 18cm tall with the thinking it would produce a stronger plant like in sweet peas. My mother told me that's not a good idea and they won't crop! have I ruined my plants?
ANSWER: It's not something I've done myself so I can't say for sure. I suspect that although you haven't done the ideal thing, the plants will sprout new shoots below where you have pinched them out. Who knows, you may have discovered a useful technique that no one else has discovered. Certainly, don't abandon them, I think all will turn out OK.
|Date: 14 March 2016||From: Peter L|
|QUESTION: I PLANTED MY BROAD BEANS IN JANUARY AND SOMETHING SEEM TO HAVE EATING ALL THE SEEDS UNDER GROUND
ANSWER: Mice or squirrels are the most likely culprits. The only measure I have heard of which works is to soak the beans in liquid paraffin before planting them.
|Date: 24 July 2015||From: Margot|
|QUESTION: I bought some broad bean plants from a nursery when they were about 12 - 18" tall with flowers on. I've never grown them before but they have several pods on now about 3 - 4" long. I planted them in June and all the plants are looking healthy with plenty of flowers and pods setting. I have pinched out the tops on the plants now but don't know when to harvest the pods for maximum flavour and tenderness. I would prefer them small and young rather than older and more mature. Please advise. Thank you
ANSWER: The only way to get them at the stage you personally prefer is to open up a pod or two and see what size they are. Much depends on the variety and growing conditions. I would suggest opening up a pod when they are about 15cm / 6in long and take it from there.
|Date: 20 July 2015||From: Rob|
|QUESTION: Could you please tell me why my broad beans are only cropping from bottom of plant to middle and not all the way up?
ANSWER: That's quite normal. I've just been down to my allotment and looked at my broad beans and my neighbour's and the beans only go roughly half way up. Different varieties will produce beans slightly differently, some may well crop all the way up but not all.
|Date: 30 June 2015||From: Francis A|
|QUESTION: White flowers on my broad beans are being eaten; any suggestions as to what is eating them and what treatment is needed?
ANSWER: It's unusual for the flowers on broad beans to be attacked, the only culprit that springs to mind are birds. They occasionally are attracted to them and leave tell tale rips in the flowers rather than eating them. Aphids are another possibility, they don't actually eat the flowers but can distort the flowers to such a degree that they may look like they have been eaten. If that's the case you will see what looks like black marks around the flowers and tips of foliage which is in fact just massed aphids.
If you us the email address in our contact page and attach a picture of the damage I will do my very best to be more specific.