Cashew nuts grow as part of the cashew tree's fruits (or apples). The cashew tree is most commonly grown in Brazil, India, Southeast Asia and parts of Africa. These trees start producing fruit young, and a grafted tree can begin fruiting in just 18 months. You can purchase seedling stock or a grafted cashew tree from a nursery, or you can grow one from fresh seeds, which are the cashew nut including the shell. Cashew seeds are easy to germinate, but they may not grow a tree that produces high-quality nuts.
Plant your cashew tree in sandy, well-draining soil. Choose a location that offers some protection from high winds and receives full or partial sunlight.
Allow a distance of about 33 feet between cashew trees if you're planting more than one. Also make sure that the cashew trees have enough room to grow up to 39 or 40 feet tall.
Support the cashew trees during the first two to three years by inserting wooden stakes beside the trees and tying the trunks to the stakes using soft string or twine.
Water your cashew trees during dry spells or times of drought. You don't need to water older, established trees regularly, but water younger trees deeply once every two weeks.
Feed your cashew trees with a fertilizer containing nitrogen, potassium and phosphorous (NPK). Fertilize the trees when they flower and again when the nuts begin to develop. Feed five-year-old and younger cashew plants a fertilizer with an NPK ratio of 4:3:2. Feed trees that are six years old and older a fertilizer with an NPK ratio of 4:3:4. Follow the dosage and application instructions on the package.
Spray your cashew trees with a zinc leaf spray to prevent zinc deficiencies. During the winter growing season, spray the tree's leaves with a solution of 7 ounces zinc oxide mixed with 26 1/2 gallons of water. For a smaller colony of cashew trees, you can use a solution of 1 ounce zinc oxide to 4 gallons of water.
Harvest the cashew nuts when the cashew apple is deep pink or red in color and the nut shell turns a dull grayish color. The best time to harvest the nuts is when the fruits are ready to fall from the tree.