Adzuki beans are a popular legume in Japan, China, and Korea. They are often called red mung beans and grow wild throughout East Asia. Adzuki beans make a fascinating specimen in your garden and are a plant rarely grown in American gardens.
Adzuki bean plants are easy to grow and perform well as container plants, where they grow vertically. These nutritious and exotic red beans can grow beautifully in your garden at home with the proper preparation.
What Are Adzuki Beans?
Adzuki beans are an annual vining plant that originates from Asia. This bean has been cultivated for so long that its origins are lost in the mists of time. Today, only soybeans are more extensively cultivated in East Asia. Adzuki bean plants tend to be bushy in appearance and about two feet tall. The bean pods are smooth and develop from bright yellow flowers in clusters.
Most of the time, you’ll find deep red Adzuki beans, but mottled beans in white, grey, and brown exist as well. One of the adzuki beans’ most common and delicious uses is the sweetened Asian red bean paste used as a filling or topping in Asian desserts. Adzuki beans offer good nutrition, easy growth and are delicious in many recipes.
How to Grow Adzuki Beans
American gardeners may find them sold in the Asian section of some supermarkets. However, growing your fresh adzuki beans is the best way to experience this ancient legume’s true flavor.
Growing adzuki bean plants is fun and straightforward enough that anyone can have success. When you know the ideal conditions for growing adzuki bean plants, you can get great results every season.
– Starting Adzuki Bean Seeds
The seed of the adzuki bean plant is the mature bean. Like many legume species, adzuki bean seeds are eager to germinate once temperatures are warm. Gardeners can sow directly into the garden once the soil temperature is above 60 degrees for several days in a row. All threat of frost has passed. Seeds will germinate in 6 to 20 days when sown in the garden.
Starting Adzuki Bean Seeds Indoors
Gardeners can get a head start on the season by beginning adzuki bean seeds indoors. You can start two to three weeks before the last frost in your region. Using a small knife, a file, or a piece of sandpaper, gently scarify the seed hull and place the beans in a shallow pan of clean water. Let the beans soak for two to four hours, then place in peat pots about one inch deep in high-quality potting soil.
Place the seed pots on a germinating mat and raise the temperature to 70-75 degrees. Most of your adzuki seeds will sprout within ten days and will be ready for the garden when the soil warms up. It would help if you did not try to transplant adzuki bean seeds as the roots are delicate. Use a starter pot that you can plant along with the adzuki bean seedling.
Where to Buy Them
Adzuki beans are easy to find in many stores. These beans can be sprouted and will grow; however, they may not be of ideal quality.
Gardeners will have the most success purchasing adzuki bean plant seeds from a reputable seed company or as young plants in the local garden center when available. Buying from a seed company lets you select a variety of adzuki beans precisely what you want.
Types of Adzuki Beans
- Takara: The most widely cultivated variety in the U.S. These medium beans are suitable for confectionary use or cooking.
- Hokkaido: This is an early-maturing variety that can tolerate wet and cool conditions.
- Wase: Another early-maturing and small variety, it’s ideal for soups and sweets.
Soil Conditions for Growing
Adzuki beans will grow well in most types of soil with a neutral pH. The plants prefer loamy, rich soil that has excellent drainage. Like other legumes, these Japanese red bean plants fix nitrogen in the soil, so gardeners should avoid using fertilizer and instead work organic compost into the garden. Nitrogen-rich soil will produce bushy plants with few beans.
– Growing in Containers
Adzuki beans are an ideal container plant because of the bushy, non-climbing nature. Use a sufficiently large barrel or planter box to provide room for the roots to spread.
Adzuki bean plants that grow in too small of containers will become root-bound and may die. A large wooden barrel or planter box with excellent drainage makes a great place to grow adzuki beans. You can also use sterile potting soil to prevent diseases.
– Proper Lighting & Temperature
Adzuki plants like to grow in sunny locations in temperatures between 75 and 90 degrees. The adzuki plant will tolerate high temperatures better than it will handle cold weather.
Avoid planting adzuki beans in shady locations as the plant will produce few flowers leading to low yields.
– Watering for Success
These tropical bean species like moist soil but can develop root rot if overwatered. The best way to water your adzuki beans is to allow water to soak the soil at the plant’s base slowly.
In most regions, watering a few times deeply per week is sufficient. In arid or hot regions, adzuki bean plants may need daily watering.
When to Harvest
Most adzuki beans grow slowly and will take at least 90 days from sprouting before they are ready to harvest. Some late-maturing varieties may take more than 120 days to produce fully.
Adzuki bean pods can be left to dry on the plant until they rattle inside the pod for shelling beans. These are the beans you’re after if you want to make Anko red bean paste. Harvest the bean pods when they are green and just showing for use in fresh recipes.
You can collect the dried pods from the adzuki bean plant throughout the growing season and keep them in an airtight container out of the sunlight. By season’s end, cut the entire plant and hang it to dry for at least a week in a cool location out of the sun.
Pop the pods open to extract the beans. Each pod will have seven to ten small red beans. Store them in a glass jar with an airtight lid in a dark place. They will keep for at least one year.
How to Make Anko Red Bean Paste
Every bean has its perfect use, and for adzuki beans, it’s best to make it into red bean paste.
It is a straightforward recipe for making the sweet filling familiar in Asian pastries.
- Sort, rinse, and drain 1 cup of adzuki beans, then soak for 1-2 hours—place in a large pot of boiling water. Reduce heat to a gentle simmer and cover. Discard and refill the water at least once during the process. Cook until tender 2-3 hours, gently mashing some of the beans.
- When the beans are cooked through, add in one cup of sugar and a pinch of salt. Continue cooking the mixture on medium heat until just thickening. You’ll be able to draw a line in the bottom of the pan with the spatula when it’s ready.
- Spread the bean paste on parchment paper to cool.
- Add to mochi balls or sweet bread.
Storage: Anko paste will keep in the refrigerator for at least a week. It can be frozen and will retain its flavor for two months.
Growing Adzuki Beans as Beneficial Garden Plants
Adzuki bean plants are a great plant to rotate into your garden periodically. The roots can improve the soil’s nitrogen, making it easier for other plants to absorb the vital nutrient.
Adzuki beans are often grown on fields that produce cotton, an essential crop notorious for being nutrient-absorbing. The bean plants can help other crops grow well in your home garden.
Excellent crops to plant with your adzuki bean plants include cucumbers, eggplant, and radishes that benefit from the soil’s nitrogen-enriching. Potato plants repel beetles that eat beans, while bean plants repel beetles that eat potatoes, making these two an unlikely but successful planting. Planting catnip near your adzuki beans can help repel flea beetles.
The most common pests in the U.S. to impact adzuki beans are flea beetles. These small, black insects eat irregular holes in leaves and can become an infestation. Bean borer beetles may be a problem in some areas. Aphids and whiteflies can also present pest problems for gardeners growing adzuki beans.
A light dusting with diatomaceous earth can help control insect populations. A mild neem oil spray can also reduce populations. Make sure to spray the leaves’ bottoms to kill eggs and larvae laid by the most common pests. Plant pest-deterrent species nearby and encourage predatory pollinators like lady beetles and many types of wasps.
The most common diseases that impact adzuki bean plants are root rot and mildew. Both conditions result from hot, humid conditions or improper watering. Mildew is a fungus that appears like white fur on the nodes of leaves and branches. Root rot makes the roots and stems mushy, and the plant will yellow and die quickly.
The best way to grow adzuki beans is to avoid planting seeds that may have diseases and use good-quality soil free of pathogens. Watering your plants the correct way can prevent most of the primary disease problems. If you have plants showing signs of disease, they should be removed from your garden and destroyed.
- Adzuki beans are commercially grown throughout East Asia and are an essential food source.
- The beans are typically made into a sweet paste.
- Adzuki beans require loose, well-draining soil, lots of sunshine, and consistent, deep watering.
- The plants can take between 90 and 120 days to harvest. Beans can be harvested green or when dried.
- The dried beans are the main ingredient in Anko, a red bean paste used for filling sweet bread treats.
- Adzuki beans are a beneficial plant to grow in your garden that provides nutrient fixing.
- Flea beetles and mildew are the most common diseases.
Adzuki bean plants make adorable container and planter varieties. The short, shrubby nature and vibrant foliage throughout the summer look great, and the vibrant yellow flowers attract beneficial pollinators. When the plants come into harvest, you’ll be surprised by the number of beans you can get from each little plant.