Adzuki Bean – All About This Plant That Is A Japanese Favorite

Those red-brown beans may be tiny, but they’re nutritional powerhouses. This flavorful, nutritious food is an annual vine called adzuki bean. Adzuki beans, Vigna angularis, are widely cultivated in Japan, China, and many other East Asia parts.

So, what is the adzuki plant, how is it cultivated, and how do you use the beans? Read on, and you’ll learn all about the versatile vines you’ve been obsessing over.

Red beans are packed with vitamins, minerals, and fibers, not to mention they’re gluten-free! Their versatile use in the kitchen makes them a garden favorite and an important food crop. They’re generally used as pulse or dried beans, but you’ll also love eating them fresh!

Common NameAdzuki Bean, Azuki, Aduki
Botanical NameVigna Angularis
Plant TypeAn Annual Vine
Size (Fully Grown)1 To 2 Feet (About 30 To 61 cm) Tall
Sun ExposurePreferably Full sun, But The Plant Can Tolerate Light Shade
Soil TypeA Soil That Is Moist But Still Drains Well
Soil pHFrom 5.8 To 6.4
Flower ColorYellow
U.S. Hardiness Zones4, 5, 6, 7, 8, 9, 10, And 11
Native AreaOrient (Japan, China, Korea, Hong Kong, And Taiwan)

Different Adzuki Bean Varieties

People have bred adzuki beans to “enhance” various features, such as color, yield, and growing time. There are even some varieties that are meant for animal feed and green manure. That’s why, only in Japan, there are over 300 cultivars.

You’ll also find local varieties in China, Taiwan, Korea, and Japan. Though you might only be familiar with the red ones, adzuki beans can also be white, gray, black, or spotted. Here are some of the most popular ones:

  1. Erimo
  2. Hikari
  3. Takara
  4. Minoka
  5. Dainagon
  6. Kita-roman
  7. Bloodwood
  8. Chinese Red
  9. Japanese Red
  10. Adzuki Express

Where Do Adzuki Beans Come From?

Wild ancestors of the Adzuki beans have existed around Japan, China, Korea, Nepal, and Bhutan for thousands of years. Domestication occurred somewhere around 3000 BC in the Orient, which includes several countries in East Asia. But the exact location of its first domestication is still unknown.

The adzuki beans that existed between 3000 to 2000 BC were much smaller in size than what we see today. The beans are now bigger because it was bred during the Bronze or Iron Age. But, the larger size came with a trade-off. These cultivated varieties had fewer pods and fewer, larger seeds in each pod. Overall, the yield was smaller than the wild adzukis.

The bean has earned different names in different cultures. It was initially called “shuzu” by the Japanese, which means “small bean,” to differentiate it from the larger soybeans. Later, the name was changed to adzuki, but pronounced as “azuki.” In old Japanese, “aka” meant “red,” and “zuki” meant soft, referring to the softness of the beans upon cooking.

The combination of the two words formed the name “azuki.” In China, “hongdou” and “chidou” are the more common names in use, both meaning “red beans.”

Currently, it’s Japan’s sixth-largest grown crop. It’s also cultivated abundantly in the Yangtse River valley in China. Adzuki beans are also grown in south China, New Zealand, India, Korea, Taiwan, the Philippines, the US, South America, and Thailand.

With its bright color, it has been a popular part of Asian cuisines for a long time. It’s mostly used to make “ann,” a popular food additive created by soaking, boiling, washing, removing the coat, pureeing, drying, and sweetening with sugar. This paste is used to fill bread (ann-pan), cakes, steamed bread, and dumplings.

What Does The Adzuki Plant Look Like?

Adzuki beans grow as an annual vine that usually reaches 1 to 2 feet (about 30 to 61 cm). The plant can have varying growth habits, depending on the variety. They can be bushy, erect, or trailing. Vertical types are more prevalent in Japan, while China and southern parts of Asia have trailing varieties.

The fast-growing vine can either climb a trellis or be left to spread over the garden bed as a prostrate plant. It gives a stunning appearance with thick foliage and long green/brown pods hanging from the branches. Under the soil surface, the plant has a strong taproot that can grow even 12 to 20 (about 30 to 50 cm) long.

© handatko – stock.adobe.com

Leaves

The trifoliate, pinnate leaves look pretty much like those on Southern peas and are arranged alternately on the stem. Individual leaflets are ovate, approximately 2 – 4 inches (about 5 to 10 cm) long and 2 to 3 inches (about 5 to 8 cm) wide.

Flowers

Adzuki produces bright yellow papilionaceous flowers, with a 6 to 7 inches (about 15 to 18 cm) long corolla. They’re bisexual and arranged in clusters of 6 to 10.

Pods

The bright flower clusters are followed by adzuki pods or the fruit of the adzuki plant. These cylindrical pods are smooth, thin-walled, and green while they’re still young.

As the fruit matures, it turns pale yellow or brown. They can have a length of 2 to 5 inches (about 5 – 13 cm) and a width of 0,2 inches (about 0.5 cm), with 2 – 14 seeds in each pod. Young pods are tender, and you can harvest and consume them while they’re still green on the vine.

Seeds

The bright red seeds are the main attraction of the adzuki vine. Though they’re commonly red or maroon, you can also find them in other colors, like green, black, straw-colored, and mottled. They’re smooth and cylindrical, with a protruding ridge along the side with a seed scar.

In What Conditions Does Adzuki Bean Like To Grow In?

Adzuki beans aren’t just healthy for you but also for your landscape. Its unique nitrogen-fixing abilities nourish the garden for your future crops.

One of its reasons for cultivation is to produce green manure.
The growing requirements for adzuki beans are quite like soybeans. Though they’re easy to grow, they’ll take a long growing season.

From sowing the seeds to harvest, it takes about 120 days for the adzuki plant to mature. If you’re planning to grow adzuki beans, here’s what you need to know:

What Temperature Adzuki Beans Tolerate?

The ideal growing temperature for adzuki beans lies in the range of 60 – 90°F (about 15,5 – 32°C), the same as for soybeans. To plant the seeds, wait until after the last spring frost, once the soil temperatures exceed 60°F (about 15,5°C).

While the seeds will sprout in 10 to 14 days with soil temperatures above 60° (approximately 15,5°C), germination can take over 20 days at temperatures between 50°F – 55°F (about 10 – 13°C). Cold, wet soil also makes the seeds susceptible to rotting, so be careful with that!

What Type Of Soil Is Best For Growing Adzuki Beans?

Plant adzuki beans at a site that gets plenty of sun throughout the day. Loose, well-drained, neutral to slightly alkaline soil rich in organic matter is ideal for growing adzukis. Good drainage is essential for healthy plant growth since adzuki vines can’t tolerate waterlogged soils.

Water And Fertilizing

Keep the soil evenly moist but not soggy. Adzuki beans are prone to rotting if they’re growing in waterlogged soil. Also, always remember to water at the base while keeping the foliage dry. This will prevent the plant from rotting and getting other plant diseases.

Fertilize the plants with a low-nitrogen fertilizer once the plants are about 4 to 5 inches (about 10 to 13 cm) tall. And once they bloom, give a second dose. Avoid using nitrogen-rich fertilizers since they’ll promote the growth of foliage at the expense of pods production.

Is It Safe To Eat / Consume Adzuki Beans?

With plenty of proteins, fibers, and minerals, adzuki beans pack bundles of health benefits, including weight loss, heart health, reduced risks of diabetes, and kidney health. Since they’re rich in proteins, adzuki beans make an excellent meat substitute for vegetarians.

But, is it safe to consume adzuki beans if you have a medical condition or if you’re pregnant? Is it safe for children? What about pets? Let’s find out.

Pregnant And Breastfeeding Women

Adzuki beans are good for women, especially during pregnancy. They’re rich in folic acid and can reduce the risks of neural tube defects, making sure your baby is healthy and strong. And that’s not all! They’re also safe for nursing moms.

Children

Adzuki beans are a healthy addition to children’s diets. They are also a part of excellent baby food, but you may want to remove the skin before feeding it since it can cause choking.

But, keep in mind that if your baby is allergic to soy, there’s a possibility that they’re also allergic to adzuki.

People With Allergies

Though adzuki is not a common allergen, it’s related to soybeans, so if you’re allergic to soy, you may want to consult a doctor before consuming adzuki. Some people with legume allergies are sensitive to certain types of legumes. Symptoms include vomiting, rash, itching, and hives.

People With Diabetes

Since it has a low glycemic index, it’s an excellent plant to eat if you have diabetes.

Pets

Though very healthy for humans, adzuki beans are poisonous to dogs. Please keep your pets safe and avoid offering them beans from your plate.

Featured image credit – © zcy – stock.adobe.com

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