Question: My son just started at the University of Hawaii at Manoa, and we were walking around the pretty tree-filled campus. We noticed a bush or small tree with what looked like edamame. But my akamai son said, "No way, Mom. Edamame grow on bushes, short bushes." Do you know what these might be? Do soybeans grow on trees? Or is my son the smart one? (We think so!) — Mrs. Proud Mom and Mr. Happy Dad
Answer: Soybeans, or edamame as we like to call them in Hawaii, do grow on bushes, and they grow well here in Hawaii. I think what you are describing is an old-fashioned plant that is becoming popular once again as people become more interested in growing their own food in home gardens, community gardens and even on the UH-Manoa campus. This sounds like gandule beans, also known as pigeon peas.
They grow on a large bush or small tree. Unlike soybeans, which will give you a crop or two in Hawaii, these are a longer-lived perennial that will keep flowering and producing ono edible peas for years. It is also an attractive plant in your garden landscape.
Pigeon peas, like all members of the bean family Fabaceae, are nitrogen-fixing plants. They improve soil fertility for themselves and for the other plants growing around them. Any trimmings or clippings make excellent "green manure," or garden mulch that will improve your soil and the health and vigor of other plants.
I first got to know about this plant when I was an apprentice gardener at the National Tropical Botanical Garden on Kauai. Nick Vera Cruz, who was a section head and gardener trainer, had them growing. I, too, thought they were big soybean bushes at first and then found out more about them from Nick Vera Cruz. We grew the seeds from him and kept them growing for some years.
Scientists call them Cajanus flavus, and they also have the Hawaiian name pi-nunu. Grow them as you would any bean, planting seeds in well-tilled, weed-free soil and covering them firmly with a half-inch of dirt. Water gently every day. Once established, you can water less often.
The plants will bear yellow pea-shaped blossoms that are pollinated and form into bean pods. As with edamame, boil or steam the pods and then pop the beans into your mouth for an ono pupu or vegetable. You can also add the cooked beans to other dishes.
Pigeon peas were brought to Hawaii early on and are widespread in drier, tropical areas today. It is probably native to Africa, but as the seeds are portable and easy to store and grow, it was carried to many places by akamai farmers and home gardeners.
In the old days they were fed to horses, cows and chickens. The plants also make a nice windbreak or edible hedge. When they become less productive after three to four years of growth, plow the whole plant back into the soil and add some free fertilizer for your next crop.
They are a key ingredient in gandule rice.
Heidi Leianuenue Bornhorst is a sustainable landscape consultant specializing in native, xeric and edible gardens. Reach her at heidibornhorst@gmail.com.
