Hyacinth Bean
Growing The Hyacinth Bean
You might think that the hyacinth bean, Lablab purpureus, given its potential for invasiveness and the toxicity of its beans, might be shunned by most gardeners. Quite the contrary. Almost everyone who has planted the hyacinth bean thinks of it as being one of the greatest plants ever. The hyacinth bean is a species of the Lablab genus, and is known as the Lablab plant in some parts of the world.
The hyacinth plant is a tropical vine, but can be grown as an annual in more temperate climates. It is quick growing, and once started will quickly cover a trellis or a chain link fence. The vines can be anywhere from 6' to 15' long and will climb on most anything climbable. One gardener planted a few seeds along with some sunflowers, presumably the tall Russian or Mammoth variety, and found the combination of sunflowers and vines to be quite striking. The plant blossoms almost continuously from late summer into the fall. The blossoms are purple in color and very fragrant. The hyacinth bean attracts honeybees, butterflies, and hummingbirds.
Invasive, But Manageable - As far as the plant's tendency to be invasive is concerned, it is seldom a problem if you place the plants where you want them to grow year after year, as while the plants die back each winter, they seed themselves if a few pods are left on the plant, and a new generation of plants will sprout the following spring. If neglected, or placed in a location where you only want a plant or two, you may eventually find yourself having to dig out newly sprouted plants over a wide area unless you take the time to remove the seed pods before the seeds are sown.
The hyacinth bean seeds are said to be poisonous or toxic, yet the seeds are eaten in many parts of the world and the plant is used as forage, especially for goats. A number of people who have eaten the raw beans claim not to have suffered any ill effects, and some even express surprise to hear that they are supposedly poisonous. It would seem that one would have to eat quite a few to feel any bad effects, but it's probably best to err on the side of caution.
Good Eating, If Done Right - The poison in the seed is a compound called cyanogenic glycosides, which sounds like it has something to do with cyanide or a type of cyanide sugar, but this compound is destroyed upon boiling or cooking, and it is the cooked bean which is eaten as food in some parts of the world. In parts of Asia, the hyacinth bean is a popular ingredient in stir-fry recipes, especially the young seed pods, and the shoots and blossoms can be eaten in salads. This plant supposedly has an affinity for heavy metals, taking them up from the ground when planted in contaminated sites. When that is the case, ingesting any part of the plant may not be healthy, but when grown in most garden soils, this should not be a problem.
The hyacinth bean is an easy plant to grow. Some say that it is difficult to get started, while others will tell you to place the seeds in the ground and stand back! It does appear to be helpful to soak the seeds awhile before planting them, and some gardeners keep the seeds between damp paper towels for a few days, then plant them as they are just beginning to germinate.
The hyacinth bean blossoms come in several colors, with purple being the most common. Some varieties feature red blossoms, and there is a variety which has yellow blossoms, although it's claimed yellow bean hyacinth seeds can be somewhat difficult to find.