Instead of summer rain, we seem to be getting a heavy dose of vog in West Hawaii. Since drought conditions appear to be ongoing in Kona, we might want to consider plants for our gardens that are somewhat drought tolerant and perhaps tough enough to withstand our current poor air quality.
Several tough species from the Erythrina genus are worth consideration. The large, native wiliwili tree, Erythrina sandwicensis, or the tall, narrow tropic coral, Erythrina variegata, might serve the purpose. For those looking for a small tree in this genus, the common coral tree, Erythrina cristi-galli, would be an ideal choice.
This lovely, small tree grows quickly to about 20 feet and develops a wide crown that can provide shade at its base. The botanical species name, cristi-galli, is Latin for cock’s comb and the bright red flowers it produces almost year-round do somewhat resemble the red comb of a male chicken in color and shape.
The common coral is a South American native. It is known as ceibo in Argentina where it is the national tree and is the national flower in Argentina as well as Uruguay.
The small Erythrina genus is a member of the very large Fabaceae, or legume (bean), family that includes nearly 20,000 species. These plants, including the Erythrina species, produce bean-like seed pods following flowering.
Another quality of most leguminous plants is their ability to ‘fix’ nitrogen. They collect nitrogen from the air and sequester it in root nodules that are produced by nitrogen fixing bacteria. These support the plant with nutritional nitrogen. This characteristic adds to the appeal of growing a common coral tree.
The common coral tree makes an attractive specimen plant due partly to its appealing shape and small stature as well as to the striking beauty of its racemes of bright red flowers. Though quite unusual, a coral tree lei can be exquisite. These dazzling blooms are also attractive to bees and birds because of the sweet nectar they produce. The thick corky bark of the tree further enhances its appealing appearance. A lush canopy of six-inch compound leaves provides a pleasant shaded area in the garden for heat relief or to accommodate a shade-loving understory.
The seed pods that follow flowering will dry and turn a dark brown. At this point the six or more seeds inside are ready for collection and planting. Once the seed pods are dry and removed, it is best to cut off remaining stems.
Though new growth cuttings can produce plants fairly quickly, seeding is the preferred propagation method for the common coral tree. Many seeds are available on the tree and they sprout easily when properly handled.
For the best germination rate, the seeds should be lightly scarified. Clipping a small break in the hard seed coat with nail clippers can accelerate the process. Plant scarified seeds in a seeding mix and keep the medium moist (not wet) until new growth appears.
Once the seeds sprout, they can be fertilized lightly and kept in a pot until several leaves unfold and the plant seems strong enough to up-pot or plant out. The first leaves, the cotyledons, of the common coral tree will likely stay underground, so it may take a while for the true leaves to emerge.
When the new plant is ready to be planted out, look for a sunny spot with soil that drains well. Be sure the location has room for this specimen to spread as it grows. It can sometimes grow to be nearly as broad as it is tall.
Though most erythrinas are somewhat drought tolerant, they all need regular watering until established. The common coral tree will survive on little water but may be more attractive if supplied with a small amount of water on a regular basis.
Very few pests are attracted to this plant with a single serious exception. The erythrina gall wasp was wreaking havoc on many in this species beginning in 2005 here on the Big Island. Several chemical treatments were employed including soil drenching and systemic injections. These methods seem to have brought the pest under control but constant observation and rapid treatment is required to minimize damage to plants in this genus.
If you do decide to grow a common coral tree, you may have to look around a bit to find one. You can always call Margo from Sunrise Nursery as she is currently helping customers locate hard to find plants. She can be reached at 329-7593.
If you want to acquire seeds and start your own plants, some are available for free to members of the Community Seed Library in the Kailua-Kona Library. Go into the library for more information on the CSL and becoming a member.
The common coral is a small tree guaranteed to please. Consider one for your garden.
Diana Duff is a plant adviser, educator and consultant living on an organic farm in Captain Cook.
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: “Sunset Farmers Market” 2-6 p.m. in the HPM parking lot at 74-5511 Luhia St. in Kailua-Kona (across from Target)
Wednesday: “Ho’oulu 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 a.m. to noon at Pukalani Stables
Sunday: “Pure Kona Green Market” 9 a.m. to 2 p.m. at Amy Greenwell Garden in Captain Cook
“Hamakua Harvest” 9 a.m. to 2 p.m. at Highway 19 and Mamane Street in Honokaa
Plant Advice Lines
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 firstname.lastname@example.org