Hyacinth bean, also known as Lablab (from its Latin name, Lablab purpureus), is a type of bean used in cooking and its ornamental value. Famous for its breathtaking purple flowers, it also produces delicious beans, improves your soil quality, and attracts friendly insects to your garden.
Our experts explain the ideal growing conditions in this comprehensive hyacinth bean grow guide while answering several frequently asked questions, such as is hyacinth bean poisonous?
Read on to find out more!
What is hyacinth bean?
Hyacinth beans are vining plants and can quickly grow more than 10 feet (3 meters) in height. Their best-known features, which also gives them their name, are the flowers and pods. What makes them unique is the color, which is usually a vivid, almost iridescent purple, growing in abundant clusters throughout summer and early autumn.
The hyacinth bean’s flowers have turned it into a very popular ornamental plant, especially in the United States, where it is often used in gardens and urban landscaping.
Not all hyacinth beans produce purple flowers, though. Nowadays, you will find varieties with pink, lilac, and even white blooms, all equally showy and easy to grow. The color of the flower also impacts the color of the pods and beans. Purple flowers will produce purple pods with dark brown seeds, while yellow flowers will produce green pods. Red or black beans are also common, mostly when dry.
Are hyacinth beans edible?
Hyacinth beans are edible, although care is needed when preparing them. Otherwise, they can cause a toxic reaction. They are also popular in traditional medicine and have been used to treat gastrointestinal problems, throat and ear inflammation, spasms, and sunstroke. A compound found in these beans has recently been used in studies on preventing the spread of the SARS-CoV-2 virus.
If we’ve made you curious about the hyacinth bean, read on to find out how you can grow your own.
Are hyacinth beans perennial plants?
The hyacinth bean is a fast-growing, warm-season crop. In its native habitat, this is a perennial plant, but in most gardens around Europe and the United States, the hyacinth bean is grown as an annual plant.
However, if you’re lucky to live somewhere with mild winters and no chance of frost and snow (such as US hardiness zones 10 and higher), your hyacinth bean plants will persist in your garden for several years.
How to grow hyacinth bean
Before you start sowing hyacinth beans in your garden, let’s take a look at some quick facts:
- Hyacinth bean thrives in warm climates and does not tolerate frost;
- It is a vigorous climber, and it will need a support system to grow on;
- This plant is susceptible to overwatering;
- The purple flowers are very showy, so you can also grow purple hyacinth bean as an ornamental vine.
1. When to grow hyacinth beans?
The best time to grow hyacinth beans is in mid-spring or early summer. Like most legumes, it needs warm temperatures and short days to start fruiting. As a result, you will only begin to see flowers and bean pods in late summer, or more commonly, early autumn.
Throughout summer, hyacinth bean plants develop leaves and numerous vines, and it’s not uncommon for this plant to grow as tall as 15 feet (4.5 meters). You will need to provide them with tall trellises or other support systems that they can climb on.
Hyacinth beans are susceptible to too much water, and soaking the seeds can cause them to rot. Fill some compostable seed pots with a potting soil mix, place one bean in each pot, water regularly, and keep temperatures above 63 °F (17 °C). The seeds should germinate in about 7 days.
Once the hyacinth bean seeds have germinated, it may take up to 3 weeks to grow two or three sets of leaves. Always wait until the seedlings have at least 4 leaves each before you transplant them to the garden soil. This way, you minimize the risk of transplant shock, killing the young plants.
Do hyacinth beans need to be inoculated before sowing?
All bean varieties fix nitrogen in the soil, using small nodules that develop on the roots as the plants grow. This also means that they will need less nitrogen-based fertilizers as they grow. The part of your garden where they are growing will develop nitrogen-rich soil that’s perfect for growing other vegetables the following year.
Many gardeners recommend inoculating beans with Rhizobium before sowing, and hyacinth bean also lends itself to this practice. Rhizobia are bacteria that exist in the root nodules of legumes, and they are the ones that do all the work fixing nitrogen in the soil.
Although they naturally develop as the bean plants grow, inoculating the seeds before sowing will improve the growth of the young plants and fruit production later on. Not only that, but studies also suggest that it enhances the cookability of the beans.
So should you inoculate your hyacinth beans with Rhizobium? The answer is: it depends.
If you’re sowing hyacinth beans in a part of your garden that has held another crop of legumes in the past 1 – 2 years, inoculation will not be necessary. Also, using plenty of organic soil amendments, such as manure, will achieve similar results.
However, if your garden soil is inferior, we suggest inoculating your beans before sowing. It will improve your chances of growing strong, healthy plants, and it will also result in an abundant harvest later on.
3. How to plant hyacinth beans outdoors
When planting hyacinth beans in your garden, always wait until any chance of frost has passed. These plants are not cold hardy, and any sudden drop in temperature will kill them.
The best temperature range for hyacinth bean is between 68 °F and 82 °C (20 °C to 28 °C). If temperatures exceed 86 °F (30 °C), the plant will struggle to produce flowers and fruit. Therefore, the best time to plant outdoors is in mid or late spring.
Pick a part of your garden that gets plenty of light. Hyacinth bean thrives in full sun and will need at least 6 hours of sunlight each day. It can tolerate partial shade, but, like temperatures that are too high, this can impact fruiting later on, and you may be harvesting fewer pods.
Prepare the soil by turning it to a depth of at least 1 foot (30 cm) and incorporating amendments such as compost and well-rotted manure. Proper drainage is crucial for hyacinth beans, as they are susceptible to having wet feet. If the soil is clay-heavy, you will need to add bark, leaf mold, or even sawdust to loosen it. Aim for a pH range of 6.0 to 6.8.
Another thing you need to prepare before planting hyacinth beans is setting up a support system. On average, these vining plants can grow to at least 8 feet (2.4 meters) in height. You can prune them to keep them in shape, but upright support is essential for a healthy plant. You can either use trellises, a garden wire fence, an arbor, or even a teepee made from bamboo stakes.
Hyacinth beans can also be allowed to climb on solid, wooden fences. However, this provides for insufficient air circulation, and as a result, the plants can become susceptible to fungal diseases, such as powdery mildew.
Once your soil is prepared, your supports are in place, and temperatures are at a cozy 64 °F (18 °C), you can start planting hyacinth beans outdoors. If you’re sowing hyacinth bean seeds, plant them 6 inches (15 cm) apart, and thin them when the young plants have 3 – 4 sets of leaves each.
Plants germinated in compostable pots and kept indoors for a couple of weeks can be planted at least 2 feet (60 cm) apart. Don’t remove them from their compostable pots —dig a small hole, and place the entire pot inside. It will decompose on its own in a month or so.
Water your hyacinth beans well, keeping the soil moist but not soggy. Like all bean varieties, they are very susceptible to root rot if they are overwatered.
Our suggestion is to regularly check the soil with your finger to a depth of around 2 inches (5 cm). Suppose the soil feels dry, water thoroughly and allow the soil to dry in between waterings. This way, you will encourage the plants to produce deeper, sturdier roots and avoid the danger of ‘drowning’ them.
Your hyacinth beans rarely need additional fertilizers. If they have been grown in soil with plenty of organic amendments, especially compost, the nitrogen they fix through their roots is more than enough to keep them going.
However, plants growing in poor garden soil will need a boost once a month after transplanting. In such cases, we recommend fertilizers that are not nitrogen-rich. A nutrient ratio of 5-10-10 should do the job.
Once they become established in your garden, hyacinth beans grow very fast and will take over their trellises and other supports in just a few weeks. To keep them under control, regular pruning is encouraged. As soon as they reach the top of their trellis, cut off the tip of the vine with a pair of gardening scissors. This will cause the plant to produce lateral vines, allowing for a more even spread of leaves and vines.
Don’t worry about cutting too many vines when pruning your hyacinth beans. New ones will grow from the bottom before you know it and fill in gaps with their abundant growth. Keeping your hyacinth bean plant well-groomed encourages it to spend more energy-producing flowers and reducing the risk of pests and diseases.
Plants clustered or growing in very compact shapes are more likely to be damaged by diseases, especially fungal and viral ones. Not to mention the fact that a messy tangle of vines isn’t the prettiest sight in your garden.
– Hyacinth bean flowers
After about 4 to 6 weeks since being transplanted outdoors, you will start noticing the first hyacinth bean flowers. The blooms are very similar to bean or acacia flowers, usually deep purple, although pale lilac and even white flowers are not uncommon.
They are very showy, and many gardeners grow hyacinth bans for their abundant clusters of flowers, which look spectacular on trellises or garden arbors. Flowers are also very attractive to bees and butterflies, which help with pollination.
If you notice that your hyacinth bean plant is not blooming, there could be several reasons for that.
Lack of flowers is typically a sign of insufficient light or too much nitrogen in the soil. It’s best to refrain from overfeeding your plants, especially with nitrogen-rich fertilizers used to stimulate leaf growth. At the same time, you can encourage your hyacinth bean to produce more flowers by regularly pruning the side vines. Cut the tips and aim for 3 to 4 pairs of leaves per vine, which will prompt the plant to spend more energy on flower development.
– Hyacinth bean pods
Hyacinth beans will produce pods from late summer until mid-autumn. The pods have a unique, vivid purple color, that starts as pink and develops a slight silvery hue as the pods mature.
Just like the flowers, these iridescent bean pods have a high ornamental value. It’s best to note that if you’re growing varieties of hyacinth beans that produce white flowers, the pods will be green, similar in appearance to snow pea pods.
4. Pests and diseases
Hyacinth beans are usually reasonably resistant to pests and diseases. However, they may occasionally be bothered by the same problems as other bean varieties. The plants can become hosts for caterpillars, which will eat the leaves and Japanese beetles. Check your plants daily, and pick these insects by hand, then throw them in a bucket of soapy water.
– Managing and preventing fungal diseases
When grown too closely, in parts of your garden that get poor air circulation or not enough sunlight, hyacinth beans are also prone to fungal diseases. In such cases, a solution of water and baking soda sprayed on the leaves will be the best cure.
Preventing fungal diseases is best, which is why we recommend regular pruning, as well as trying not to pour water on the leaves and vines when watering your plants.
– Rust spots
Other diseases may be a bit more challenging to manage, especially rust. If you notice that the leaves are developing brown or reddish spots, take action immediately, as rust disease spreads very fast.
Use a pair of gardening scissors to cut the infected leaves and vines, and dip the scissors in a bleach and water solution after each cut. Burn any sections that were cut off, or throw them in your general rubbish bin. Do not add them to your compost bin, as rust will spread to other plants in your garden the next time you use it.
– Other problems
You can also use the same control method for dealing with fusarium and verticillium wilt on your hyacinth beans. Sadly, there is no effective cure for these two fungal diseases, and they can persist in your garden soil for many years after the first infection.
Once they attack the plants, regular pruning of the affected leaves and vines can help keep the plant alive. However, our recommendation is to remove the sick beanstalks and roots and burn them to avoid spreading the wilt to the rest of your garden.
5. When to pick hyacinth bean pods
Hyacinth bean pods can be harvested both when they’re young and when the pods have matured. For young pods, wait until each one has at least 3 or 4 beans growing inside, forming small lumps under the shell. You can pick them regularly throughout summer, up until early fall. Snap the stem that connects them to the vine, taking care not to damage the plant in the process.
Mature hyacinth beans should wait until the pods start to wrinkle or until they are fully dry. Usually, this means waiting until mid to late autumn for the harvest. Picking the mature pods is easy and can be done by only using a pair of gardening scissors to cut off the vine they are growing on.
Remove the shells of mature beans, as they are not edible. Inside, the beans should be dark red, brown, or even black, depending on the cultivar. They should also exhibit a white hilum.
– Storing hyacinth bean pods
Fresh hyacinth bean pods can be kept in the vegetable drawer of your fridge for 3 to 4 days, although eating them fresh is best. Mature beans will need to be shelled, and stored in a cool, dry place, preferably in an airtight container. They will keep well for at least a year, and you can either save them for eating or for sowing again next season.
– After the harvest
Hyacinth bean plants will start to wilt around mid-autumn, so once they’ve been harvested, they can be cut down. These plants are commonly grown as annuals, but they can also grow back as perennials, depending on your climate.
For example, if you live in a US hardiness zone of 8 or above, you can cover the plant’s base with mulch, and it will grow new vines in spring. Otherwise, frost is very likely to damage the roots over winter, so it’s best to remove the entire plant and sow the following year.
Uses for hyacinth bean
Hyacinth bean is a very versatile plant, and it has numerous uses. It is often grown for its ornamental value, as a flowering vine, and its bright purple flowers can be a real showstopper in many gardens.
Hyacinth bean is also popular in insect-friendly gardens, especially if you wish to attract bees and butterflies. Given that they fix nitrogen in the soil, they are also perfect for growing in gardens that practice crop rotation each year, as they enrich the substrate with nutrients for future crops.
1. Cooking with hyacinth beans and leaves
The most common use for hyacinth beans is in cooking. All parts of the plant are edible, from the pods and beans to the leaves, vines, and even flowers. The beans are rich in protein and fiber and minerals such as magnesium, iron, zinc, and phosphorus. Their taste is very similar to that of other bean varieties, although the young pods have a more pronounced green bean flavor and a slightly stringy texture.
Hyacinth beans are popular in many traditional dishes around eastern Africa and Asia. The young pods can be eaten raw, although they are best used in stir-fries, garlic and ginger, boiled, blanched, or sautéed. The pods will lose their color when cooked and turn slightly green. Mature, dry beans are a common addition to curries, especially in India, soups, stews, and can also make tofu.
Hyacinth bean leaves can be used the same way as spinach, while the vines can be gently steamed and served as a side dish. The flowers also make for a unique garnish, adding a touch of color and mild aroma. The most important part when cooking with hyacinth beans is knowing how to prepare them. This leads us to address a very pressing question…
… Is hyacinth bean poisonous?
Many people have concerns about the edibility of hyacinth beans, and in a way, they are right to think so. The dry hyacinth beans contain cyanogenic glycosides, a compound that is converted into hydrogen cyanide when consumed. As a result, dry beans that haven’t been adequately cooked can cause vomiting, shortness of breath, twitching, and convulsions.
So how do you cook dry hyacinth beans so that they’re safe to eat? The trick is to boil them 2 or 3 times, changing the water after each boil. Soak the dry beans overnight, then boil for 10 to 15 minutes. Drain and rinse them with warm water, then add back to the pot and top with boiling water. Repeat the process at least two times. Once this is done, your hyacinth beans can be used in the recipe of your choice.
It’s worth mentioning that this process of repeat boiling is only needed for dry hyacinth beans. The fresh, immature pods can be eaten raw, the same as the leaves and vines. However, the taste and texture when raw may not be the best, so our tip is to cook them instead.
Hyacinth beans bring a lot to both your garden and your plate!
Stunningly beautiful, versatile, and delicious, it’s a superb plant for any garden. Plus, growing hyacinth beans is just as easy as other, less exciting bean varieties with this guide.
Let’s recap the basics.
- Hyacinth beans love warm climates but should not be overwatered.
- You’ll need to set up a sound support system for it, as it’s a fast climber.
- For best results, prune your hyacinth bean vines regularly.
- All parts of the young hyacinth bean plants can be eaten, including leaves, beans, pods, vines, and flowers!
- If you plan to cook with the dried beans, it’s essential that you prepare them properly!
There are lots to love about the fantastic Hyacinth bean, so why not grab a pack of seeds and try it yourself!