Psophocarpus tetragonolobus
The first time I encountered winged beans, I was on a family trip to Hawaii and we’d walked past a market stall full of vegetables and fruits.
As I pursued the baskets full of rambutan, starfruit, lychee, and dragon fruit, I encountered some of the strangest beans I’d ever seen.
At first I didn’t even realize they were beans, with their odd ruffled edges making them almost look like some type of giant caterpillar.
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Winged beans (Psyphocarpus tetragonolobus) are tropical, perennial legumes. All parts of the plant are edible, from the tuberous roots to the flowers.
The winged beans are notable for their distinctive shape – four longitudinal ridges or “wings” run along the pods, with ruffled edges.
If you live in USDA Growing Zones 10 to 12, you can grow winged beans as perennials. Otherwise, plan to grow them as annuals.
Whether you’re new to winged beans or you’re lucky enough to have grown up with these leguminous wonders, this guide will cover how to cultivate them in your own garden.
Here’s what’s ahead:
P. tetragonolobus is native to Papua New Guinea and widely cultivated in tropical regions of Southeast Asia.
They are also known as goa beans, four-angled beans, dragon beans, or shikaku mame in Japan.
P. tetragonolobus is sometimes confused with the asparagus pea aka winged pea, Tetragonolobus purpureus – but this species has red instead of blue flowers, and only the cooked pods can be consumed.
These vining plants produce a lot of food in a small footprint, growing up to 15 feet long and about two to three feet wide.
Those grown as annuals are unlikely to achieve these dimensions during one growing season.
The winged bean plant as a whole packs quite the nutritional punch.
The underground tubers resemble potatoes and contain 20 percent protein by weight. The seeds have 35 percent protein and are packed with carbohydrates, vitamins B1, B2, B3, B6, B9, C, A, and E.
Prior to the pods forming, pale blue flowers develop in the spring. These edible flowers make a tasty addition to salads.
Quick Look
Common name(s): Winged beans; dragon, goa, four-angled beans; shikaku mame
Plant type: Perennial vine
Hardiness (USDA Zone): 10-12 (perennials)
Native to: Asia
Bloom time / season: Spring, summer
Exposure: Full sun
Soil type: Loose, humus-rich, well draining
Soil pH: 6.0-7.5, slightly acidic to neutral
Time to maturity: Up to 180 days
Spacing: 3 feet
Planting depth: 1 inch (seeds)
Mature size: 2-3 feet wide x up to 15 feet high
Water Needs: Moderate
Taxonomy
Order: Fabales
Family: Fabaceae
Genus: Psophocarpus
Species: Tetragonolobus
After the flowers open, they’re pollinated by bees, butterflies, and flies, and the pods start to form.
It only takes about three weeks for the winged bean pods to reach their ultimate length of up to a foot and then a few more weeks to be ready for harvesting.
The species is day-length sensitive and must have longer days than nights for at least a week or two before they will flower.
I live near the 45th parallel and that means the days are long enough around mid-March, but it’s too cold at that time for the plants to be outside.
You can find winged bean cultivars that are day-length neutral or short-day if day length is an issue for you.
The curious-looking pods start out green but as they mature they can be green, cream, pink, or purple with cream, green, white, tan, or brown beans inside.
The leaves are typically green, but they can also have some purple shading, and these can be prepared a bit like spinach.
We don’t know where wild winged beans originated. The progenitor has been lost to time and may be extinct. It’s possible that this species is a result of crossbreeding different wild legumes.
How to Sow
Because these plants need such a long growing season – up to 180 days for mature seeds – many gardeners opt to start seeds indoors and then move them out as soon as the weather warms up.
You can also buy nursery starts, though they’re hard to find in cooler regions.
Immature, green pods are typically ready between 75 and 110 days from planting.
For many gardeners, myself included, we will only have enough time for the pods to mature and not the seeds, but that’s fine! You will still have lots of pods, leaves, flowers, and stems to eat.
From Seed
You can start your seeds 12 weeks ahead of transplanting. You’ll need to figure out when soil temperatures will be consistently above 60°F, as you can’t transplant before that.
- Soak the seeds for 24 hours and then gently nick them with a knife before sowing.
- Fill four-inch containers with well-draining seed starting medium and moisten it.
- Sow seeds an inch deep, one in each container.
- Set the pots on a heating mat, to keep the soil consistently between 75 and 85°F.
- Keep the soil evenly moist but not waterlogged.
- After germination, move the growing pots into an area where the seedlings will receive at least six hours of direct sunlight per day or provide supplemental lighting.
- When the seedlings are about six to eight inches tall, pinch the growing tips to encourage bushier growth and robust root development.
Plan to transplant when soil temperatures are reliably over 60°F and be sure to harden them off first.
Transplanting
To put seedlings into the ground, the first step is to work the soil a little to loosen it up. Amend with some well-rotted compost to about six inches deep.
Then dig a hole the size of the container the transplant is currently growing in.
Remove the plant from its pot, set it in the hole and backfill with soil.
Firm the soil up around the base of the plant and water the soil well. If the soil settles, add a bit more.
Space the plants about three feet apart but within six inches of a support structure.
How to Grow
Part of what makes these plants so fantastic is that they’re super adaptable.
Light
Like many legumes, these tropical vines prefer a full sun location, with six or more hours of direct sunshine per day.
If you live in a very hot region, you can give young plants a bit of shade from strong afternoon sun, but once established they will be fine.
Soil
Winged beans are quite happy in average soils, provided it is well-draining.
They can’t handle waterlogged, heavy clay, with standing water so if your garden is predominantly clay, consider growing in a raised bed.
Otherwise, you can work in some compost to the ground before planting to increase water retention and improve drainage.
Temperature
These tropical plants like it hot! The ideal growing temperature is around 75°F and above, so you don’t want to plant too early.
If temperatures drop below about 58°F, growth stops completely.
If you need to make sure the temperatures are warm enough, you can grow them against a south-facing brick wall because the brick will help to provide additional heat.
Water
Keep the soil consistently moist while the vines are becoming established and when they flower, allow the top one or two inches to dry out between waterings.
When they are established, winged beans are drought-tolerant.
Weeding
The vines can be slow to start, so you need to be on weed patrol. It’s easy for weeds to overtake the young seedlings.
As the temperatures heat up, the vines grow more quickly and can outcompete weeds.
I like to put an inch or two of straw mulch or leaf litter all around the plants to help retain water and keep weeds away.
Support
The plants must have something to climb up.
You could tie a string to horizontal poles, use cattle fencing, buy bean trellises, or anything else that can support the vines as they grow.
Fertilizing
Feed your plants with a balanced food with an NPK around 10-10-10 or 12-12-12.
Better yet, test your soil before feeding and then feed your soil according to the results of the soil test.
I like to use Southern Ag’s all purpose granular fertilizer, which has an NPK ratio of 10-10-10. Feed when the plant starts to flower and again one month later.
Southern Ag All Purpose Granular Fertilizer
You can find Southern Ag All Purpose Granular Fertilizer available via Amazon.
Pruning
The vines grab onto things by twining, so they’ll spin their way up anything they can reach.
You’ll find them twirling their way up fence poles, or twisting up nearby trees or shrubs. They’ll even twine their way up other plants in your garden like tomatoes or corn stalks.
Prune any vines growing where you don’t want them.
If the plant becomes too bushy on top, it can shade the inner and lower vines and they won’t produce flowers and pods.
Prune out some of the vines if the plant should be flowering but isn’t. Or remove vines if the whole thing is becoming unruly.
You can take off a lot of the foliage and the plant will be fine. Don’t be delicate about this, just get in there with some pruners and go to town.
Cultivars to Select
Mostly you’ll just find generic winged bean seeds for sale, though there are a number of cultivars available.
If you would like to grow the species plant, find seeds available in a variety of packet sizes at True Leaf Market.
Winged Beans
If daylight hours are a limiting factor for you, you’ll want to seek out one of the cultivars that aren’t daylight dependent.
All of the following are worthwhile options:
Local Green
‘Local Green’ is a short-day cultivar, which has made it popular as a winter season crop in places like Guam.
It will flower and produce when the days are shorter than 12 hours. The resulting plants are robust and high-yielding.
Singha
‘Singha’ is an early flowering cultivar that is day-neutral. That means an early harvest regardless of what the daylight hours are doing in your region.
Urizan Japanese
This is my favorite cultivar because it’s reliable and matures early, though it might just be because it’s the only cultivar available in my region.
I got my seeds from a friend, but you can find this heirloom day-neutral cultivar at several rare seed or plant retailers.
Pests and Disease
Since the entire plant is edible, it’s appealing to herbivores like deer and rabbits. Insect infestations common in the veggie garden will also attack winged beans.
Here are the main pests and diseases to affect these plants:
Pests
As with most vegetables, aphids can be an issue. In particular, the black bean aphid (Aphis craccivora) can’t get enough of winged beans.
Usually, an infestation isn’t a big deal unless the plant is extremely young.
Learn more about dealing with aphids here.
In tropical regions, the winged bean blotch miner (Leucoptera sophocarpella), bean pod borer, (Maruca vitrata), and cotton bollworm (Helicoverpa armigera Mylabris afzelii, and M. pustulat) can damage the foliage and flowers.
If you’re growing in North America, it’s only the second two you need to worry about.
Root-knot nematodes can also infect the plants, specifically Meloidogyne arenaria, M. incognita, and M. javanica. Learn more about these microscopic pests here.
Disease
Winged beans are generally vigorous plants and it’s not often you’ll have to deal with a disease.
Especially if you keep them well spaced and pruned if they start to become overgrown.
Collar Rot
Collar rot is a disease caused by numerous fungi, including species in the Fusarium, Rhizoctonia, and Macrophomina genera. Infection causes rot at the base of the plant, eventually killing all the vines.
If this rot extends through the base, turning it mushy and black, it will kill all of the vines.
When the disease is present, it is hard to control, but you might be able to stop it by applying a powerful biofungicide that contains hydrogen peroxide or Bacillus subtilis.
CEASE Biofungicide
Arbico Organics carries an effective product called Cease, which contains the beneficial bacterium B. subtilis.
It’s best as a preventative but it can slow or stop the progression of the disease.
False Rust
False rust or orange gall is common in crops grown in tropical regions, but it has only been identified as moving into subtropical areas as of 2024.
If you’re growing outside of a tropical region, you probably don’t need to even think about this problem.
This disease is caused by the fungus Synchytrium psophocarpi and shows up as orange pustules on leaves, stems, pods, and flowers.
It can also cause leaf distortion and a reduction in pod size and quality.
The second you see any pustules forming, which start out green before becoming orange, start treating with a broad-spectrum fungicide like mancozeb.
Bonide Mancozeb Flowable with Zinc
Grab a 16-ounce bottle of Bonide Mancozeb Flowable with Zinc at Amazon and apply according to the manufacturer’s directions.
If you live in a subtropical region, report the infection to your local extension office so they can document its presence.
Powdery Mildew
Powdery mildew (caused by the fungus Erysiphe cichoracearum) is very common in the vegetable garden.
It causes white powdery coating on the leaves. Our guide to powdery mildew has more details.
Harvesting
As the vines grow, feel free to pluck off leaves here and there to use as you would spinach.
If you want to eat the pods rather than the beans, wait until they reach their full length, which should happen a few weeks after flowering, and snip them off the vine.
If you have a long enough growing season, you can let the pods mature on the vine. They will turn brown and eventually split.
At that point, you can remove the seeds and dry or cook them fresh.
The tubers need several years to become large enough to harvest, so only those growing these plants as perennials will get to enjoy them!
Preserving
The leaves, immature pods, and flowers should be eaten within a few days of harvesting.
Freshly harvested pods will keep for up to a week wrapped in a cotton or paper towel in a plastic bag in the fridge.
The seeds or beans can also be dried by placing them in a single layer on a baking tray or screen and allowing them to sit until they become dry and brittle.
Rotate or stir the beans every day to ensure even drying. You can also dry them in a dehydrator on a low setting.
Once they’re dry, you can put them in a cloth bag and store them in a cool, dry place.
Cooking Ideas
Use the flowers fresh to top salads and as garnishes. The leaves are also perfect in salads, or try them on sandwiches or on pasta.
The stems can be eaten raw, but chop them up and saute them with some butter, garlic, and salt for a real treat.
You can eat the tubers either raw or cooked. If you eat them raw, slice thinly for salads, or use them like potatoes if you decide to cook them.
The pods can be used just like any edible pod bean. They’re a classic option in stir fries, of course. You can saute them in garlic, butter, and red pepper flakes.
Yum tua pu is a tasty Thai salad made with roasted peanuts, coconut flakes, shallots, mint, and boiled eggs with a spicy Thai dressing. It’s phenomenal.
You can eat the pods when they’re immature or let them mature a bit, though not to the point where the beans inside are plump and start to harden.
The seeds or beans must be cooked before eating. You can roast them, dry and grind them up into flour, turn them into milk, or extract the oil.
Speaking of, the oil extracted from winged beans is even better than soybean oil because it’s more thermally stable and is high in antioxidants.
This Bean Has Wings
Winged beans are an excellent choice for gardeners in tropical or subtropical climates. They’re a bit more of a challenge to cultivate in more northern regions, but it can be done.
It’s rare that you find a plant that can provide edible flowers, leafy greens, pods, beans, and tubers. P. tetragonolobus has it all.
Are you growing winged beans? I can’t wait to hear how you’re going to use your harvest. Let us know in the comments section below!
And for more information about growing beans in your garden, read these guides next: