Yardlong Beans Plant Profile

Long beans

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Yardlong beans are a subspecies of the cowpea (Vigna unguiculata), an annual legume that is an important crop in many warm regions of the world. Yardlong beans (subsp. sesquipedalis) are related to black-eyed peas (subsp. unguiculata), and they go by many names, including Chinese long beans, asparagus beans, pea beans, and snake beans. Yardlong beans live up to their name, often growing up to 3 feet in length, although they are usually eaten before they reach their mature size. They are especially popular in Chinese and other Asian cuisines, with a taste that is less astringent than string beans (Phaseolus vulgaris).

Yardlong beans grow quite well in most climates. The compound leaves are bright green, with three heart-shaped leaflets. The flowers and resulting bean pods usually form in joined pairs. Flowers look as you'd expect of a legume (papilionaceous) with five petals, the largest on top. The size and color will vary with variety—either white, pink, or lavender. The long vines set copious numbers of delicious dangling rope-like beans throughout the summer and continue producing until the weather turns cold.

Yardlong beans are generally planted in the spring once the soil is warm. The seeds will emerge in 10 to 14 days; after about 80 days, beans can be harvested.

Botanical Name Vigna unguiculata subsp. 
Common Name Chinese long beans, asparagus beans, yardlong beans
Plant Type Annual vegetable
Size 8 to 12 ft.
Sun Exposure Full sun
Soil Type Dry, sandy
Soil pH 6.0 to 7.5 (slightly acidic to slightly alkaline)
Hardiness Zones Annual, grown mostly in warm zones
Native Area Africa
Toxicity Non-toxic

How to Plant Yardlong Beans

Direct sow yardlong beans after all danger of frost is past and the soil is at least 60 degrees Fahrenheit. If you are worried about not having a long enough season for the beans to mature, you can warm the soil by covering it with black plastic a few weeks before your last frost date.

Sow yardlong bean seeds about 1 inch deep, spaced about 3 inches apart. Rows should be spaced about 24 inches apart. Thin out the plants to a 6-inch spacing as the seedlings emerge. In warm zones, you can succession plant two or three times at two-week intervals, and also plant a late summer or fall crop.

Because beans are legumes, they can benefit from applying a soil inoculant before planting. Coating the seeds with inoculant will help the plants to take nitrogen from the air to use as fertilizer.

Yardlong beans have long vines, often growing 8 to 12 feet tall. Except for dwarf, bush varieties, you will need to give them a tall support or grow them along a fence. Put your trellis or other support in the ground at planting time. If you can reach to harvest it, a teepee of 7 feet is a good size for the beans to scramble on. Don't make the poles any larger than 2 inches in circumference, so the vines can take hold.

Yardlong Bean Care

Light

These beans need a full sun location. Shade will reduce flowering and bean production.

Soil

Yardlong beans are not terribly finicky about soil pH, but they do best with a pH between 6.0 and 7.5. Yardlong beans are true legumes, so a soil without too much organic matter is best. Too much nitrogen will result in more leaves than beans. These plants will do well even in dry, sandy soil.

Water

While yardlong beans are fairly drought-tolerant, prolonged dry spells will make the pods tough and they won't grow as long as they should. Ideally, give these beans 1 inch of water each week.

Temperature and Humidity

Yardlong beans grow tall before setting flowers and need a long, warm period early in the growing season. Don't be surprised if they don't take off until the temperature heats up and stays there. Ideal growing temperatures are 70 to 80 degrees Fahrenheit. They will stop growing as the weather cools down in the fall. These beans are native to arid regions, and they grow equally well in dry and humid environments.

Fertilizer

Like other legumes, yardlong beans generally don't require supplemental feeding, since they fix their own nitrogen from the air.

Yardlong Bean Varieties

  • 'Liana' is a day-neutral variety that starts producing early in the season—70 days after germination. It is also recommended as a fall crop in warm climates.
  • 'Purple Podded' is a good choice for hot climates. It retains most of its color when stir-fried. This variety takes 90 days to mature.
  • 'Red Noodle' is similar to 'Purple Podded', but more flavorful with a crunchier texture. Seed germination to harvest is 95 days.
  • 'Stickless Wonder' is an unusual dwarf variety. The vines only grow to about 30 inches tall and do not need trellising. Plants start flowering early (40 days) but like many bush beans, they don't have as long a season as taller vining varieties. Seed germination to harvest is usually about 54 days.
  • 'Yard Long' (white seeded, black seeded, red seeded, extra long): Often you will find seed packets labeled only as Yard Long Beans, but there are subtle differences between varieties. Any of the green varieties offers a good place to start experimenting. They mature in about 90 days.

Harvesting

It can take two to three months for yardlong beans to start flowering from seed, and the beans follow in about two weeks. Once the beans form, it does not take long for them to start growing longer and longer. The beans lose their dense, crispness as the seeds inside fill out, so harvest them while they are still firm, usually between 8 and 12 inches long and thinner than a pencil.

Once yardlong beans start producing, you may need to harvest almost daily to keep the plants productive. The beans will keep several days in the refrigerator. The pods tend to grow in pairs, which makes harvesting a little easier.

You can use yardlong beans interchangeably with green beans, but they truly shine in stir-fry dishes, where they lend a mysterious flavor. These are the beans traditionally used for the Chinese green bean dish offered on many Chinese restaurant menus. They are also commonly cooked with fermented bean curd.

Propagating Yardlong Beans

The seeds inside the beans can be saved for planting the following spring. Allow the beans to fully dry on the stalks before harvesting them and breaking them open to collect the seeds.

Common Pests and Diseases

Yardlong beans are not as prone to bean beetle damage as green beans. It's the small, often unnoticed pests you need to look out for, like aphids and thrips (especially early in the season).

Unfortunately, the tender shoots and leaves are attractive to deer, rabbits, groundhogs, and other small animals. Sturdy fencing is the only prevention.