Reminiscent of wind-swept tropical beaches and desert islands, coconut palm trees (Cocos nucifera) grow mainly in southern Florida, the southern tip of Texas and Hawaii in the United States. Hardy in U.S. Department of Agriculture plant hardiness zones 10 through 12, coconut palms are grown as ornamental trees and for their fruit. Coconuts can travel thousands of miles floating on ocean currents, so the trees' native homeland is unknown but is thought to be the South Pacific or Malay Archipelago.
Size and Appearance
Coconut palms are among the tallest palm trees. Growing 50 to 100 feet tall and 20 to 40 feet wide at their canopies, coconut trees are single-trunk palms with slender, light gray trunks that are often curved and swollen at the base. Coconut tree leaves are downward arching and grow up to 20 feet long, containing as many as 200 leaflets. Flowers can appear year-round, and trees begin flowering when they are 4 to 6 years old. Light yellow female and male flowers appear together on branchlets 2 to 4 feet long -- female flowers at the bases and smaller, male flowers at the ends. In cultivation, coconut trees usually grow 20 to 50 feet tall, depending on the cultivar, and dwarf forms are available.
Coconuts thrive in full sun and well-drained, mildly acidic to mildly alkaline soil. Tolerating salt spray and high humidity, they grow in oceanfront sites and in dry inland areas below 1,000 feet. Growing best at temperatures between 70 and 80 degrees Fahrenheit, coconut trees fare poorly at temperatures below 64 degrees Fahrenheit, and freezing temperatures cause permanent damage and death. They require 60 to 80 inches of water per year, through rainfall or irrigation, and tolerate temporary flooding and high winds. Trees grow well in moist, moderately fertile soils high in organic matter, spaced 25 feet apart.
Diseases and Deficiencies
Lethal yellowing and nutrient deficiencies are common problems for coconut trees. A disease spread by leafhoppers, lethal yellowing has killed hundreds of thousands of palm trees in Florida. Symptoms begin as premature coconut fall and blackened flower stalks and progress to yellowing in the lower leaves. Eventually, the yellowing spreads to the top of the canopy and the tree dies. Injections of an antibiotic called oxytetracycline are an effective prevention and help keep affected coconut trees alive. Coconut trees are also susceptible to potassium deficiency, which causes yellow-orange or black spotting on leaves and dead leaf margins and tips. New foliage is yellow, short and frizzled. Sulfur-coated potassium sulfate spread every three months at a rate of 1 1/2 pounds per 100 square feet of canopy supplies coconut trees' potassium needs.
Coconut trees produce their large, nutritious fruits year-round. Taking 10 months to mature, coconuts contain protein, fat, carbohydrate, calcium, phosphorous, iron and a range of other minerals and vitamins in their meat, which is the inner, thick white lining, and in their watery, sweet milk. The meat is dried and shredded for use in cakes and candy or pressed for coconut oil, which is an ingredient in many cooked foods and margarine. Coconut meat that has had its oil extracted is called coconut cake and is used as a livestock feed. The outer husks of coconuts are the source of coir, a material used in potting soil, ropes, matting, packing material and fuel. Coconut trees even produce drinkable sap from the cut ends of flower branchlets.