The lowly pigeon pea offers many benefits to akamai gardeners. Not only is it a drought-tolerant, small and attractive tree but it also offers an edible crop and fixes nitrogen. As the leaves of pigeon pea trees provide filtered shade for your garden, they are also collecting nitrogen from the air to sequester in your soil.
Though not widely grown in Hawaii today, pigeon peas have been cultivated in tropical areas for more than 3,000 years likely beginning in India. Since they have been identified in African archaeological sites dating back to 2,000 B.C., they are also possibly native to tropical and sub-tropical Africa. Many Europeans took pigeon pea plants home from Africa and it was through the slave trade in the seventeenth century that they made it to the American continent. They were reportedly introduced to Hawaii in 1824 and were widely planted here during World War I. Today, pigeon peas are grown commercially in many countries as a protein-rich food crop.
A member of the very large legume/bean or Fabaceae family, the pigeon pea (Cajanus cajan) has countless relatives. Most of them are legumes with similar flowers, which produce pods containing beans or peas and have a high percentage of nitrogen in their leaves, stems and roots.
Pigeon peas are consumed as a protein source by both humans and livestock in many parts of the world. They can be shelled and eaten as fresh peas or harvested when the pods are dry and stored as dry beans for cooking and eating later. In parts of the Caribbean pigeon peas are known as gandules and in India, as dahl. They have even been growing in Hawaii long enough to have a Hawaiian name. They are known as pi nunu (pigeon pea) or pi Pokoliko (Puerto Rican pea).
These pea trees are often planted as hedges or as support for vines like vanilla and lilikoi. Parts of the trees are often chopped and used as green manure on farms as well as in gardens. Their strong tap room means they can help prevent and control erosion and, when grouped, they can provide a windbreak to protect more vulnerable plants.
Because of its numerous beneficial uses, the pigeon pea is often described as a permaculture plant. Many videos about this plant appear on YouTube. A short one describing the plant’s usefulness is at https://www.youtube.com/watch?v=hpd_7JNiWkM.
Though it starts slowly, the pidgin pea tree soon starts to grow quickly. In the first year, it can reach over 5 feet. Classified as a shrub or small tree, it rarely grows taller than 15 feet during its life. Pigeon peas are known as perennials, which means they continue to grow from year to year. In ideal conditions they may live up to eight years, but occasionally they have a shorter life span of four to five years. During their first year, they will produce flowers and beans. This makes it possible to replant from seed bi-annually to keep a constant supply of trees growing.
The small ovate leaves grow in triplicate on slender green branches and, if it is trimmed as a tree, the branches can offer shade below. Within the first year in the ground, pigeon pea plants will produce lovely yellow flowers streaked with red. They attract honey bees and carpenter bees as well as other pollinators. Numerous pods will appear once flowers are pollinated. These can be harvested early, before they dry, and shelled as fresh peas. If left to dry on the tree, the pods will contain peas that can serve as dried beans or as seeds for a new crop
Propagation from seeds is the preferred method and requires little effort. The hard, dry seeds need some scarification to encourage quick sprouting. Nicking them with a nail clipper or sanding a small section and soaking overnight in water can help. They will usually sprout in one or two weeks in a moist (not wet) medium.
Once the true leaves appear on the seedlings you can plant them in deep pots or tree tubes and fertilize lightly to get them strong. Be sure not to wait too long to plant out, as you don’t want to abort the tap root development.
To plant them, choose a sunny spot in soil that drains well. Select a planting spot where the tap root will have room to grow. Water the new plant until it gets going. Pigeon peas are hardy plants that can tolerate many different soil types and growing conditions. Their deep root system means they can tolerate drought, so you can cut back on water once they are established.
When the plant begins to develop branches, you can either trim off lower ones to encourage a tree like growth habit or use a reduction cut (also called a drop crotch cut) on the top to keep it small and shrub-like. The trimmings make excellent mulch for your garden.
Beyond occasional optional pruning to control size and shape, pigeon peas need very little care. They are not prone to disease or insect attacks. If either occurs, treat with organic products if you plan to eat the peas, feed them to livestock or chickens or will be using the trimmings for mulch on edible plants. You can fertilize lightly to encourage growth but since they acquire nitrogen from the air, heavy fertilizing is not needed or desired.
For the many reasons enumerated here, pigeon pea trees are definitely a worth considering for your garden. Though they appear in various spots around the island and are cultivated on some farms, the seeds may be hard to find. Several online sources are available if you can’t find local seeds. Try this plant and don’t forget to donate some of your dry seeds to the Community Seed Library in the Public Library in Kailua-Kona.
Diana Duff is a plant adviser, educator and consultant living part time in Kailua-Kona.
Gardening Events
Saturday: “Work Day at Amy Greenwell Garden” from 9 a.m. to 12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Call Peter at 323-3318 for more information.
Farmer Direct Markets
Wednesday: “Hooulu Farmers Market” 9 a.m. to 2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay
Saturday: “Keauhou Farmers Market” 8 a.m. to noon at Keauhou Shopping Center
“Kamuela Farmer’s Market” from 7:30 a.m. to 1 p.m. at Pukalani Stables
“Waimea Town Market” from 7:30 a.m. to noon at the Parker School in central Waimea
“Waimea Homestead Farmers Market” from 7 a.m. to noon next to Thelma Parker Gym in front of Thelma Parker Library.
Sunday: “Pure Kona Green Market” 9 a.m. – 2 p.m. at Amy Greenwell Garden in Captain Cook
“Hamakua Harvest” 9 a.m. to 2 p.m. at Hwy 19 and Mamane Street in Honokaa
Plant Advice Lines
Anytime: konamg@ctahr.hawaii.edu
Tuesdays &Thursdays: 9 a.m. to noon at UH-CES in Kainaliu – 322-4892
Mon., Tues. &Fri: 9 a.m. to noon at UH CES at Komohana in Hilo 981-5199 or himga@hawaii.edu