Growing and Saving the Seed Of Long Bean

Latin name Vigna unguiculata subs sesquipedalis, also known as yard long bean, noodle bean or asparagus bean, is actually a variety of cowpea. It is a subtropical/tropical annual climbing vine that is very easy to grow in a wide range of climates, even northern ones. This legume family member is a different genus from the common green bean.  Long beans are a top choice for very warm climates where other beans struggle.



Believed to be native to Africa, where the wild form still exists. The long bean was mentioned in ancient Chinese texts dating back to the Song Dynasty in 1008 CE.


  • Use immature beans like green beans.
  • Dried beans from mature pods can be used like cowpeas or black eye peas.




  • Direct sow well after all chance of frost has passed and soil has warmed substantially. (Long beans love heat but they detest cool soil!)
  • Northern growers or anyone looking to get a bit of a jump on the season can also start them indoors in 4-inch pots and carefully transplant out when soil has warmed.
  • Ideal germination temperature is 68-75 F.
  • Sow seeds 1/2- 1 inch deep and 3 inches apart, thinning to a final spacing of 6 inches apart.
  • Be sure to grow up a trellis or fence, as these vines like to climb.
  • Seeds germinate in 10-15 days.


  • Provide full sun and a warm location with a trellis, teepee or fence to climb. Vines are vigorous and will reach 6-10 feet in optimal conditions.
  • Prefers loose, well-drained soil and average water needs. Plants can be slow to start flowering, but once pods set, they grow very fast. Keep an eye out for the quick-growing beans. Harvest when beans reach 12-18 inches long or when they are about as thick as a pencil. The thinner they are, the more tender.
  • Aphids and ants are often found around the blooms of long bean. You can knock them off with a hard blast of water from the hose.


  • This self-pollinating annual in the legume family will not readily cross with other nearby varieties, so a distance of 10-20 feet between other cowpea or long bean varieties is sufficient to ensure pure seed.
  • It is super easy to save seed; just allow pods to dry and for seeds to become dry and hard.
  • You should not be able to dent the seed with your thumbnail.
  • Store seeds in a cool, dark, dry place.