Yard long beans live up to their name, often growing up to 3 ft. in length, although they are usually eaten before they reach their mature size. You may know them by their other common name, asparagus bean. Despite that common name, yard long beans are not related to nor do they look anything like asparagus.
Yard long beans are popular in Chinese and other Asian cuisines. They are more closely related to cowpeas (Vigna unguiculata) than string beans (Phaseolus vulgaris). The taste is less astringent than string beans.
Yard long beans have an Asian flair, but they grow quite well in most climates. The long vines set copious amounts of their delicious dangling rope-like beans throughout the summer and continue producing until the weather turns cold.
- Leaves: Bright green leaves are compound, with three heart-shaped leaflets.
- Flowers and pods: The flowers and resulting bean pods usually form in joined pairs. Flowers look as you'd expect of a legume (papilionaceous) with 5 petals, the largest on top. The size and color will vary with variety, either white, pink, or lavender.
Vigna unguiculata subsp. sesquipedalis
Long beans go by many names. Asian vegetables have a tendency to be named either for their description (black radish) or the area they are grown. Whatever they are labeled, you will know them when you see them. Some common names you may find them called include:
- Asparagus beans
- Chinese long beans
- Pea bean
- Snake beans
- Yard long beans
Long beans are grown as annuals, so they are not given a hardiness zone rating.
Long beans need full sun, to do well. They 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. They will stop growing as the weather cools down in the fall.
Days to Harvest
It can take 2 to 3 months from seed for yard long beans to start flowering, but 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 beans inside fill out, so harvest while they are still firm, usually between 8 and 12 inches long and thinner than a pencil.
Once they 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.
Using Yard Long Beans
You can use asparagus beans interchangeably with green beans, but they shine in stir-fries where they give the dish that mysterious flavor. They are the bean traditionally used for the Chinese green bean dish offered on many Chinese restaurant menus in America. They are also commonly cooked with fermented bean curd.
The Best Varieties to Grow
- Liana: A day-neutral variety that starts producing early in the season. It is also recommended as a fall crop in warm climates. (70 days)
- Purple podded: Good for hot seasons. Retains most of its color when stir-fried. (90 days)
- Red noodle: Similar to purple podded, but more flavorful with a crunchier texture. (95 days)
- Stickless wonder: 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. (54 days)
- Yard long (white seeded, black seeded, red seeded, extra long): Often you will only find seed packets labeled as Yard Long Beans, but there are subtle differences between varieties. Any of the green varieties would be a good place to start experimenting. (90 days)
Yard long beans are not terribly finicky about soil pH, but they do best in a soil with a pH between 6.0 and 7.5. Yard long beans are true legumes, so a soil mildly rich in organic matter is best. Too much nitrogen will result in more leaves than beans.
Direct sow after all danger of frost is past and the soil is workable. If you are worried about not having a long enough season for them to mature, you can warm the soil by covering it with black plastic, a few weeks before your last frost date. Sow yard long bean seeds about 1 inch deep spaced about 6 inches apart. In warm zones, you can succession plant 2 to 3 times, at 2-week intervals, and also plant a late summer or fall crop.
Yard long beans have long vines, often growing 8 to 12 ft. 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 ft. 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 grab hold of them.
Help the young seedlings find their trellis. With a little initial training, your yard long beans will soon be able to grab and climb on their own.
Besides keeping the beans harvested, the biggest maintenance is keeping the plants watered. While yard long beans are somewhat drought tolerant, prolonged dry spells will make the pods tough and they won't grow as long as they should.
Pests and Problems
Unfortunately, the tender shoots and leaves are attractive to deer, rabbits, groundhogs, and other small animals.