Yardlong beans, also known as asparagus beans, are very closely related to cowpeas. Like regular green beans, they should be cooked and not eaten raw.
Yardlong beans are green seedpods that are not fully ripened, just like regular green beans. The pods are quite tender as long as the seeds inside them don’t get very large. You can sauté, blanch, or pan-fry them briefly and add them to any vegetable dish. If you harvest fresh yardlong beans that are approx. 40–50 cm long, about 4–6 beans should be enough for a meal. The most common preparations involves cleaning the beans before you cook them by removing the stems, as well as frequently cutting the beans into shorter pieces.
Yardlong beans are great cooked and eaten either as a salad or in stews. Woks are ideal for cooking yardlong beans. In the tropics, people prepare the plant’s young leaves like spinach and eat them as a vegetable. The seeds can be germinated and used like sprouts. Yardlong bean shoots can be used like asparagus, which is one reason they are sometimes called asparagus beans. In Asia and Africa, the beans are often canned.
Preparation: Wash the beans and cut into approx. 5 cm long pieces. Chop the garlic, and grate the ginger. Heat the oil in the wok, and stir-fry the beans for about 5 minutes until they start to brown and shrivel a little. Add the ginger, garlic, and pepper, and cook a little longer until the garlic starts to brown. Add the soy sauce and cook for approx. 30 seconds more. Season again with pepper and serve.
You can find vegan recipes with yardlong beans at the bottom of the text or in the sidebar: “Recipes that contain the largest amounts of this ingredient.”
Yardlong beans are difficult to find in Western countries. If you can find them, they are usually in well-stocked organic or Asian grocery stores, but you can also buy seeds for growing yardlong beans in gardening centers or online. You can plant these seeds in a greenhouse and grow your own fresh beans.
Green, unripe yardlong beans will only keep for a few days in the refrigerator. After that, they will lose their crispness and appear limp. The dried seeds can be kept for over a year in a cool, dry location away from direct light.
When they are not fully ripened, yardlong beans contain almost 90 % water and only approx. 3 % protein. The protein content increases as the seeds ripen (up to 22 % crude protein). Yardlong beans contain potassium, calcium, phosphorus, magnesium, and folic acid. Unfortunately, most of the beans’ vitamin C is lost during extended cooking. However, vegans get enough vitamin C anyway.
The phytic acid (an antinutrient) in the seeds of yardlong beans can somewhat reduce the absorption of the beans’ minerals and proteins.1
Select CLICK FOR under the photo of yardlong beans to see the nutrient tables. These tables provide complete nutritional information, the percentage of the recommended allowance, and comparison values with other ingredients.
Like other types of beans, yardlong beans are said to have antidiabetic, blood-purifying, and diuretic properties.2 Their high fiber content is beneficial for digestion.
Black-eyed peas, like yardlong beans, are a cowpea cultivar and can be eaten raw. We are not sure whether yardlong beans should be eaten raw, though some people say they can. They are sometimes used raw in Thai salads, but these recipes often refer to the beans as snake beans rather than yardlong or asparagus beans.
Please note: If beans contain phasins (a type of lectin), symptoms of poisoning may occur. Phasins are sensitive to heat, however, so you can reduce them in your food by briefly blanching the beans or denature the phasins by allowing the beans to boil for about 20 minutes. Learn more about how phasin and the lectins affect the human body in the following CLICK FOR:
If consumed in excessive amounts in their uncooked state, lectins can cause symptoms such as nausea, diarrhea, and vomiting. The best known lectin is phasin, which is found in especially high amounts in kidney beans.
During digestive processes, mechanical forces cause structural damage to cells on the surface of the stomach and intestines, which are normally subject to rapid repair. Lectins have a tendency to bind to the cells lining the digestive tract. According to several studies, the toxic effect of lectins is based on the suppression of these repair processes and leads to cell death. Since the protective barrier is as such disrupted, the body resorts to other protective mechanisms to quickly rid itself of the chyme, which can lead to vomiting, diarrhea, and the like.8
However, not all lectins are the same, and the amount is also of great importance. One study has identified a lectin in cowpeas,9 yet these are edible raw.
Perhaps this is a result of the African origin of cowpeas and its close relatives in contrast to others such as American beans, which are known for their toxic effects when eaten uncooked.
We were unable to find any reliable information on lectins associated with yardlong beans (Vigna unguiculata subsp. sesquipedalis) as of June 2021. To be on the safe side, we therefore advise against eating these beans raw in larger quantities. If in doubt, start by eating a small portion to see how your body responds and then increase the amount if desired.
The Zentrum für Kinderheilkunde (Center for pediatrics) at University Hospital Bonn (UKB, gizbonn.de) has an advisory on the phasins in bean pods and beans (Phaseolus vulgaris). They say that even a few seeds from a bean pod can cause symptoms.
Symptoms usually appear after 2 to 3 hours. The severity of the symptoms varies greatly from person to person. Symptoms usually include nausea, abdominal pain, and vomiting. Concomitant diarrhea can be bloody. In addition, fever, chills, sweating, seizures, and shock can occur.
First aid: if you consume even a few seeds from yardlong bean pods, drink plenty of fluids. According to the literature, doctors recommend ingesting active charcoal to prevent poisoning for patients who have eaten approximately 5 seeds. If the patient has consumed a larger quantity of seeds or if the quantity of seeds is unknown, contact a toxicologist about how to expel toxins.7
Some websites have exaggerations like this: when consumed, the red blood cells clump together, and severe metabolic damage occurs. Symptoms include seizures, bloody diarrhea, shock, and chills. If children eat five raw beans from the garden, they will die. The more often these statements are copied, the harsher they sound.
Eating yardlong bean leaves cooked with rice is said to soothe earaches. Nursing women used to boil the leaves with alum (potassium alum) to curb breast milk production while weaning their children.
Yardlong beans probably originated from African cowpeas, which were imported to and then bred in Asia (China). The plant’s origins, however, are not 100 % clear. It could also be that yardlong beans, like cowpeas, are a subspecies of Vigna unguiculata.3 In the sixteenth century, yardlong beans reached the West Indies and came to the US around 1700.
Today, yardlong beans are very popular in many tropical lowland regions. China, India, Indonesia, Nigeria, Ghana, Uganda, California, Suriname, and the Philippines are important areas of cultivation. Yardlong beans are now also grown to a lesser extent in Central Europe, where they only grow in greenhouses because the plants need a very warm environment.
Yardlong beans are annuals that are propagated from seeds. The plants develop into bushes without the help of trellises. If you grow yardlong beans on trellises, wires, or strings, they can reach a height of 2 to 3 meters. The flowers are self-pollinating, which is good because they don’t even bloom for an entire day. By noon they will already have faded.4 The first bean pods can be harvested after about 2 months.
The beans are pencil-thin and grow to approx. 50 cm, or even 90 cm in extreme cases. The longer a yardlong bean is, the more fiber it contains. The young pods are creamy-white and change color to green or red as they ripen. It is important not to damage the stems while the beans are harvested, so most growers use scissors to cut the beans down. Yardlong beans’ skin must still be smooth. If the pods are allowed to ripen, each will contain 15 to 20 seeds. The seeds are cream-colored and can have a brownish or reddish cast. Whiteflies and spider mites are particularly common pests in greenhouses.3
Yardlong beans (Vigna unguiculata subsp. sesquipedalis) are legumes (Fabaceae). The term sesquipedalis refers to the beans’ length: sesqui = one and a half, and pedalis = belonging to the foot. This type of wild bean was also eaten by the ancient Egyptians, Greeks, and Romans. In addition to being closely related to cowpeas, yardlong beans are also related to catjang peas.
The plant’s ripened seeds are often processed into flour. They are also suitable for increasing the protein content in livestock feed. In agriculture, yardlong beans can also be used as a ground cover or mulch.5 In Asia, the plant also serves as an ornamental plant for adding a green touch to fences.6
Other common names are: asparagus beans, long-podded cowpeas, Chinese long beans, bodi/bora, snake beans, or pea beans. The most common German term is Spargelbohne (lit. asparagus beans).