Epic Gardening is reader-supported. When you buy through links on our site, we may earn an affiliate commission. Learn more

How To Grow Soybeans: Edamame From Scratch

When you think of soybeans, what comes to mind? Large agricultural fields full of bushy plants, or maybe you think of soy milk or tofu. Either way, if you haven’t considered growing your own soybeans, then exploring how to grow soybeans may inspire you to plant your own soybean crop. 

Some claim soybeans are the oldest food crop in the world, which isn’t surprising, considering soybeans are more than a food source. Then there is edamame, the immature green soybeans that are popular in Asian cuisines. If you haven’t eaten edamame, then you are missing out on a scrumptious meal or snack and once you try them, you will want to grow your own. 

Soybeans are an easy crop to grow and care for because they don’t need a lot of special attention, plus they are similar to other bean crops (though not the same). This guide will go over exactly what you need to do, from sowing to harvesting soybeans, so you can be munching on your own edamame by the end of the growing season.

Good Products At Amazon For Growing Soybeans:

Quick Care Guide

How to grow soybeans
Let’s discuss how to grow soybeans! Source: UDel Carvel REC
Common Name(s)Soybean, edamame, soya bean
Scientific NameGlycine max
Days to Harvest45-65 days for fresh harvest
LightFull sun
Water1 inch per week
SoilWell-drained
FertilizerAged compost midsummer
PestsAphids, Mexican bean beetle
DiseasesFungal and bacterial blight

All About Soybeans

Commercial soybean field
A commercial soybean field can be massive in size. Source: UnitedSoybeanBoard

Soybean plants originated in Southeast Asia by Chinese farmers in approximately 1100 BC. A colonist brought the first seed to America in 1765. Common names include soybean, edamame, and soya bean. The botanical name is Glycine max as glykys means sweet in Latin.

Soybeans are a high source of natural fiber and protein. The edible portion is the bean, which is cooked or steamed first before consumption. Beans are also made into candles, cleaning products, plastics, and hair-care products just to name a few. The soy bean is an ideal cover crop to reduce weeds and add organic matter to your soil. 

If you haven’t seen these popular beans growing in a farmer’s field, then you might be unsure what this herbaceous annual looks like. It’s an erect bush that can grow up to 5 feet tall, though most average 2-3 feet tall. Each plant can yield upwards of 100 pods that grow to 1.5 to 3 inches long. 

A pod grows from self-fertilizing purple or white flowers that rise from stem nodes. Each stem will have three individual oval-shaped leaflets at the terminal end. Pods arise from each flower and grow in groups of two or three. The seeds in the hairy pod can be green, brown, or yellow, with 1 to 4 seeds per pod.  

The life cycle of the soybean plant has eight stages (depending upon when you harvest the bean). These include seed, germination, seedling, growing plant, flowering, small pod, large pod, and mature pod. In the coming sections, we will discuss how to grow, care, harvest, and store your soybeans.  

Planting Soybeans

Soybean seeds are best planted directly into the garden bed in the early spring as soon as the soil temperature is 60F. These beans are not frost-tolerant, but you can plant soybeans in late winter in warmer regions since planting times differ. Sow soybean seeds 1-1.5 inches deep, placing them approximately 4 inches apart. Space your rows at 2 ft to allow room for the bushy plants to grow. 

As long as they receive plenty of sunlight, warmth, and space, you can plant soybean seeds in a raised or in-ground garden bed. Take care not to over-water the soybean seeds because they rot easily. 

If you live in a cold climate with a short growing season, plant soybeans indoors 6 to 8 weeks before your last frost date. Transplant young plants outside as the soil warms, spacing them 4-6 inches apart. Planting soybeans too late in the season (even early summer) will affect the size of the plants and soybean yields. However, you can choose soybean varieties that mature earlier. 

If you don’t have the space, opt to grow the soybean seed in a container that is at least 12 inches in depth. This will provide plenty of room for sturdy roots. Monitor the soil moisture in the pot since it will dry out faster compared to garden soil.  

Care

Soybean roots
Soybean roots develop nitrogen-fixing nodules. Source: UnitedSoybeanBoard

Let’s explore specific care tips for growing soybeans so your plants thrive from sowing the seed to harvesting the crop. Fortunately, soybean plants grow well once they meet all the basic growing conditions.   

Sun and Temperature

Plant soybeans in full sun (8 hours of sunlight per day), otherwise partial shade areas will prevent your soybean crops from maturing and adversely affect soybean yield. Soybeans grow in USDA growing zones 2-11, so choose a soybean variety that will thrive in your climate. 

The best growth is seen with temperatures between 70F and 95F. When the weather is too hot or too cold, these legumes will not thrive. They are not frost-hardy and damage occurs when temperatures drop below freezing. 

Water and Humidity

Keep the soil moist after planting and until the seeds have germinated, though do not overwater. Soybeans can tolerate some humidity as long as they don’t get overly hot, such as temperatures above 95F. Once the plants are at the larger vegetative stage, plan to water at a rate of 1 inch per week. 

Water in the morning at the base of the plant to keep the foliage and flowers dry. As flowers form, increase the amount of water to 1.5 inches per week and then as small pods form, increase further to 1.75 inches per week. Soaker hoses or drip irrigation work well for soy.

These beans aren’t drought-tolerant, so it’s best to have a watering plan in place for the growing season. Stop irrigation once the pods have filled out and you notice a few leaves and pods turn yellow.  

Soil

Soybeans grow well in neutral to slightly acidic soil, with a pH range of 6-6.8. They will tolerate poor soil, but for the best results, plant them in well-draining loamy soil with an organic mulch to keep the weeds at bay and prevent drying of the soil. Loamy soil has an even amount of clay, silt, and sand. It will drain well and hold the right amount of moisture.

Fertilizing

There is no need to add nitrogen fertilizer to the soil while the soybeans mature. Since soybeans are a legume, they perform what’s called nitrogen fixation. They form a symbiotic relationship with nitrogen-fixing bacteria in the soil to convert atmospheric nitrogen to usable nitrogen. In turn, the plant supplies carbon to the bacteria. Otherwise, soybeans aren’t heavy feeders, so an aged compost applied mid-summer will supply plenty of nutrients until it’s time to harvest. 

Pruning

The variety of soybean you grow in the garden will determine how tall and bushy the plant becomes. Most soybeans grown in home gardens reach 2 feet tall and don’t require any type of pruning. If the plant becomes overgrown and takes space from other plants in your garden, you can prune back the invader. 

Propagation

As mentioned earlier in the planting section, the best way to propagate soybeans is to sow them 1-1.5 inches deep directly into the garden once soil temperatures warm to 60F. Usually, in the late spring if the air temperature is at least 70F. Don’t soak the seeds before planting and don’t overwater before germination has occurred.  

Harvesting and Storing

Soybeans
Dried soybeans can be planted or stored for later cooking. Source: matsuyuki

This next section covers harvesting soybeans and how to store them fresh and/or dry. We’ll look at other methods for storing so you can find the one that works best for you.

Harvesting

The time to harvest soybeans depends on whether you want edamame (the green pods) or dry soybeans. The pods will typically reach maturity at the same time, so you can pick them all at once. Edamame (the immature soy bean) is ready when the pods are 2 to 3 inches, bright in color, and plump. For this type of harvest, simply pick the pods off of the plant.

Mature pods (for dried soybeans) aren’t ready to harvest for another 2-3 months; giving them a total growing time upwards of 100 days. The leaves on the plant will turn yellow and the pods will turn brown, showing they are ready for harvest. Now you can pull out the whole bush and hang it upside down to allow the beans to continue drying. Once dried, pick the shells from the plant, and remove the beans from the pod. After the harvest, toss any remaining plants into the compost

Storing

Fresh soybeans keep well in the refrigerator for approximately 7-10 days. Place shelled or unshelled soybeans in a well-sealed container. Raw soybeans should never be eaten raw because they are not easily digested. Cooking them makes them ready for human consumption.

You can freeze immature soybeans (edamame); either with the pods or just the fresh beans. Bring a pot of water to boiling, add a pinch of salt and then boil the edamame for 3 minutes. Plunge into ice water to stop the cooking process, drain, and then dry them with a towel. Place into a freezer bag and freeze immediately. Frozen beans will keep for up to one year. 

Another option is to dry the immature soybeans for a healthy, crunchy snack. Cook the shelled beans in water for 7 minutes. Once cooled, coat them with salt and olive oil. Place them on a baking sheet and bake in the oven at 200 degrees for 6 hours. Alternatively, you can dry plain edamame in a dehydrator. Store dried edamame in an air-tight container for 2-3 months. 

Shell dried mature soybeans and place them in an air-tight container. You can store them for 1-2 years in a cool, dry place. They will last longer if kept at a constant temperature of 50-60 degrees Fahrenheit.  

Troubleshooting

Tops of soybean plants
The tops of soybean plants in a commercial field. Source: UnitedSoybeanBoard

When you grow soybeans on a small scale in the home garden, you won’t encounter as many pests and diseases compared to a commercial farmer. However, there are a few common concerns worth mentioning.

Growing Problems

The biggest growing concern is getting your soy beans to germinate. Most gardeners will over-water the seeds, thus causing them to rot from too much moisture. Water enough to moisten the soil, but don’t let the soil become saturated after planting.  

Another concern is pods falling off the plant, which happens when the plant becomes stressed. A few pods here and there aren’t an issue, but when you see multiple falling off, you will need to intervene. Most of the time, it’s related to over-watering or under-watering, too much heat or not enough warmth.

Soybeans planted in sunny locations in the garden do well if the temperature isn’t extreme. If you live in areas that receive extreme heat, your soybeans may thrive better in partial shade. 

Pests

Common pests that affect soybeans are bean beetles and aphids.

Mexican bean beetles are a pest that attacks the legume family. They are related to the ladybug but are larger and a light yellow color. If left on the plants, they will eat leaves, pods, and stems. Pick the beetles from the plants and remove yellow egg clusters from the underside of the leaves. Diatomaceous earth spread around the base of the soybean plant may help prevent infestation. 

Aphids are a common pest that likes to attack a variety of vegetables. They are tiny, oval-shaped, and can be bright green, tan, yellow, or dark brown. Damage from these pests can kill your plant and you will see decreased growth, mottled and/or curled leaves. Blast them off the plants with water or use organic insecticidal soap. Encourage lady beetles to come to your garden to keep the aphid population down too. 

Diseases

Soybeans are prone to fungal infections such as root rot, powdery mildew, and Cercospora leaf blight. One form of root rot can cause Sudden Death Syndrome which has become a huge issue with soybean crops. Prevention is the best method to reduce the chance of these affecting your plants. Soybean plants need plenty of space which allows airflow. Also, water from ground level and ensure your garden has well-drained soil. 

Another concern is bacterial blight, which is an airborne and water disease that enters through any wounds on the plant. Affected plants will have yellow and brown leaves, making it so the plant can’t uptake water and nutrients. Blight will continue to spread rapidly to the rest of your crop. Prevention is also key. 

Implement crop rotation and keep pest damage to a minimum. In the early stages, cut off damaged leaves and stems with clean tools, and apply fungicide to prevent further spread. If the damage is severe, it’s best to remove the whole plant before it spreads to others. Organic fungicides are most effective for prevention, not treatment. 

Frequently Asked Questions

Soybeans drying on the vine
Soybeans drying on their vines in the sun. Source: Stephen Downes

Q: How long does it take to grow a soybean?

A: If growing soybeans for their fresh pods they will need 45 to 65 days to mature. However, if you want dry beans they will need at least 100 days. 

Q: Is it easy to grow soybeans?

A: Yes, they are easy to grow as long as you have at least 45 days of temperatures over 70F. After planting they need warmth, sun, and moderate moisture. They don’t require a high amount of nutrients as they are nitrogen fixers.


The Green Thumbs Behind This Article: