There are several types of palm trees, including the type often used in landscapes in Hawaii, coconut palm trees. Many can be found in resorts, along beaches and even in some gardens.
Although the origin of the coconut palm is debated, there are several varieties found throughout the world. Most of the varieties found today are domesticated. The trees are generally either tall, often with yellow or green husks, or dwarf. Most of the dwarf varieties are named from their origins such as the Samoan and Malayan coconuts. The dwarf coconuts tend to be self-pollinating, but cross-pollination does occur with the tall varieties, resulting in trees of various height.
The Hawaiian word for coconut is niu. Just about every part of the plant was used by the early Hawaiians.
The husk of the fruit was used as fuel and for fiber to make cordage. The shell was used to make bowls and cooking and eating utensils. The water was drunk and the meat was eaten. The leaves were used as thatch and woven into baskets, and the trunk was used for drums and construction.
Today the husk fiber, or coir, is used to make brushes, mats or rope. The husk is also chopped and used for a horticultural planting medium, especially for orchid and anthurium growers. The coconut oil is used for cooking and cosmetics.
Gardeners can grow their own coconut plants from seed. Coconut plants grow in well-drained soil, with a temperature of 70-80 degrees, in areas with high humidity and 40 to 60 inches of rainfall a year.
When the coconuts fall from the tree, shake the nut to see whether it has water in it. Soak the entire nut in water for two to three days. Select your site but keep in mind the expected height of the tree and that the fibrous roots can extend up to 20 feet from the tree. Dig a shallow hole, place the nut on its side and bury the lower third of the coconut. Water the soil every couple of days.
The coconut should germinate in three to six months. The roots will emerge through the husk, and the first shoot will look like a green spear and emerge from the broad end of the nut that was attached to the tree. The plant will grow using the nutrients in the nut for the first year.
After the first year, gardeners should apply a complete fertilizer with analysis similar to 10-10-20. Apply 1 pound of fertilizer in the spring and fall during early growth, and increase the fertilizer to 5 pounds per year for mature trees. The plants begin to form a trunk after about five years.
The coconut rhinoceros beetle is a new pest in Hawaii. Adult beetles are fairly large, about 2 inches long, dark brown to black, and bore into the center of the crown, injuring the young tissue and feeding on the sap. The beetle grubs are white with a brown head and reach up to 3 inches long. The grubs are usually found in green waste, mulch and compost piles.
The coconut rhinoceros beetle is native to the Asian tropics and is found in the western and central Pacific islands, including the Philippines and Guam. It is not known how the beetle was introduced to Hawaii, but it was first detected on coconut trees in the Pearl Harbor and Hickam areas in 2013. Adult beetles have since been found in traps at Barbers Point, Nanakuli, near Mililani and at Diamond Head on Oahu.
Other insect pests include the coconut mealy bug, scales and whiteflies. These insects suck the plant sap and excrete a sugary substance called honeydew. Ants feed on the honeydew, and sooty mold grows on it, covering the leaves with a black mold. Rats can be a problem, feeding on the young leaf tissue. Some coconuts in landscapes can be seen with a metal band around the trunk to prevent rats from getting up into the leaves.
A serious fungal disease of coconuts causes Phytophthora fruit and heart rot of coconut.
Infected fruits are brown or black, and the young leaves are often the first to die. Once the infection moves into the heart of the plant, the plant often dies within a year.
Richard Ebesu is an extension agent with the Kauai Cooperative Extension Service.
