How to Grow Asparagus Beans

Asparagus beans, also known as yardlong beans, snake beans, or Chinese long beans, are a summer favorite that flourish in hot weather and produce abundantly. In addition to being easy to grow, they are rich in protein, vitamin B, iron, and calcium. Learn how to grow asparagus beans with these 5 helpful tips.

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5 Tips for How to Grow Yardlong Beans

1. Plant asparagus beans at the right time

Asparagus beans are a warm-season crop. They should be planted outdoors once the danger of frost has passed and soil temperatures are consistently above 50˚F (10˚ C). This is usually late spring or early summer. Asparagus bean seeds sprout and grow best in warm weather, and need a long, warm growing season (at least 75 days of frost-free weather).

When summer temperatures climb, many vegetables can’t take the heat – but asparagus beans flourish.

In the low desert of Arizona, plant from March 15 through July.

Varieties to Try:

• PLANTING GUIDE: Each month lists vegetables, fruit & herbs to plant outside & seeds to start indoors.
• HARVEST GUIDE: Photos show what may be ready to harvest that month.
• Planting dates are for the low desert of Arizona (zone 9b).

2. Choose a good location to plant snake beans

Asparagus beans thrive in well-drained soil. Beans don’t need overly-rich soil, but appreciate some extra compost at time of planting. Asparagus beans prefer full sun, so choose a location that receives at least 6 to 8 hours of direct sunlight. If you live in a hot climate, consider planting your beans in a spot that receives some shade during the hottest part of the day.

These beans love warmth and grow best when the air temperature is between 77-95˚F (25-35˚C).

• Don’t grow where legumes (peas or other beans) have grown the previous year. 
• Increase the harvest by using an inoculant of nitrogen-fixing bacteria on the seed or in the soil at planting time. 

3. Plant seeds in the garden – don’t transplant them

Beans, as a general rule, should be direct sown in the garden. The root systems of beans are shallow and grow best when undisturbed. Plant seeds 1 inch (2.5 cm) deep. Space beans 3-4 inches (7-10 cm) apart. Once your seedlings emerge, thin them to 6-8 inches (15-20 cm). apart.

Asparagus beans need consistent moisture to thrive. Water them deeply once a week, and more frequently during hot, dry weather. Avoid getting the leaves wet when watering, as this can lead to fungal diseases. Overwatering, however, can cause the roots to rot.

Common diseases include bacterial blight and mosaic virus. To prevent these, ensure good air circulation around your plants and avoid working in your garden when the foliage is wet.

Pests can include aphids, spider mites, and bean beetles. Regularly check your plants for signs of these pests. Check plants daily, remove infected leaves and handpick pests to prevent problems from becoming larger.

4. Give snake beans something to climb

Asparagus beans are happiest when growing up, and will easily climb 10 – 12 feet or more (3 – 3.6 m). Plant bean seeds at the base of a trellis or cattle panel with plenty of straight vertical supports. Put supports in place at planting time to avoid disrupting roots of growing plants. 

Growing asparagus beans vertically not only helps manage the plant’s growth but also keeps the beans off the ground, reducing the risk of disease. It also makes harvesting easier, and keeps the beans from being eaten by ground-living insects (rollie-pollies, I’m talking about you!)

5. Harvest asparagus beans correctly

Although called “yardlong” beans, harvest the beans when they are between 10-12 inches (25-30 cm) long for best flavor. Pick the beans when they are still slender, before the seeds inside have fully developed. If the pod becomes soft or spongy, you’ve waited too long; the beans inside the pod are developing and the pod’s flavor changes.

To harvest the beans, twist the bean off the vine rather than pulling. Asparagus beans are usually produced in pairs at the terminal bud. Twisting off the beans will leave the vine intact and ready to produce more beans.

Snake beans grow fast and should be harvested often. Keeping beans picked encourages more production. Leaving plants on the vine signals to the plant that its job is about over, and it slows down production.

To save seeds from asparagus beens leave several beans on the strongest plant until they are mature with large seeds inside a papery husk. Save them inside in a brown paper sack until completely dry to share and plant next season. Store the seeds in a cool, dry place until you are ready to plant them.

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