Can You Grow Cashews in Texas?

Nut Production Locations

• Early Portuguese and Spanish explorers took cashew trees with them throughout the tropical world. India and Brazil are the primary producers of cashew nuts, along with Southeast Asia, Central America, East Africa, Peru, Venezuela and Colombia. Cashew trees can't tolerate freezing weather. In the United States, cashews are grown in extreme southern Florida, Hawaii and Puerto Rico. In Texas, the semitropical USDA zone 9 Gulf Coast area, including Galveston, is too cold for cashews because temperatures there occasionally fall below 20 degrees Fahrenheit. Even in the Brownsville area, growing cashews is chancy because of occasional cold spells that would kill the trees. A temperature of 16 degrees Fahrenheit occurred in Brownsville in December 1989.

Only One Nut Per Fruit

• Cashew fruit is a strange-looking structure. The kidney-shaped true fruit starts development below the stalk that holds it onto a branch. The fruit changes color as it grows: first pink, then green, greenish gray and finally grayish brown. Above the seed, however, a false fruit forms as the stalk enlarges into a pear-shaped, bright-red or yellow, edible, 2- to 4-inch-long cashew apple. Some areas grow cashews for the cashew apple crop and don't harvest the nuts, which have been an international crop only since after World War I. In home orchards, the cashew apples are the crops that can be harvested safely.

Dangers of Nut Production

• The kidney-shaped true fruit has a double-walled shell. The outer, hard, gray layer is separated from an inner shell by a softer layer that contains a caustic oil, urushiol. The cashew tree is in the same family as poison ivy (Toxicodendron radicans), which also contains urushiol. Opening the shell to reveal the nut releases the urushiol, which causes pain, blistering, dermatitis and allergic reactions. Each nut is soaked and roasted to remove all traces of the oil, and the process makes the nuts safe to eat. The hard shell, however, still has to be removed, a laborious task by hand. Cashew harvesters wear gloves to separate the true fruit from the cashew apple and sell the unshelled seeds.

In the Landscape

• In the tropics, cashew trees grow more than 30 feet tall, but they are smaller in less optimal conditions. The trees' smooth, leathery, green leaves are 6 to 7 inches long. Cashew trees used for landscaping grow from fresh seeds under 1 year old and begin to produce fruit after three or four years. The seedlings require careful transplanting because of their fragile root systems. Cashews need full sun exposure and well-drained soil. In Texas' USDA zone 10a, cashews may grow best in the most protected microclimate available. Keep the trees pruned to 15 feet tall for easier cashew apple harvesting and to make the addition of cold protection for them easier when the temperature approaches 32 degrees Fahrenheit.