The macadamia nut, also known as the Australian or Queensland nut, grows on large evergreen trees native to southeastern Queensland. The trees can grow to a height and width of 40 feet. In the wild, the trees grow near streams and in rainforests. There are two species of macadamia nut trees: the smooth-shelled macadamia and the rough-shelled macadamia, as well as hybrid varieties. In the United States they are grown in Hawaii and California for nut production. Although the trees can be planted from seed, they may take over five years to produce a crop. For more immediate results, select healthy transplants from a nursery or macadamia grower.
Select your planting site. Macadamia nut trees need full sun and are sensitive to wind. If you live in a windy area, choose a wind-resistant variety such as Kau or Pahala.
Test soil pH. Macadamias prefer acidic soil with a pH of 5.5 to 6.5.
Amend soil with poor drainage by adding peat, wood chips or tree bark to the top layer of soil.
Plant the tree root ball in the soil site and water the soil well. Water the tree regularly, particularly during dry periods. Once the tree begins to flower and set fruit, pay special attention to watering and be sure to keep soil moist. Drought may cause flower and fruit drop.
Fertilise your macadamia tree six months after planting. California Rare Fruit Growers (CRFG) recommends using a citrus mix or fish emulsion with no more than 1 per cent nitrogen content. Fertilise about twice a year.
Harvest nuts when they fall to the ground, usually in late fall and spring. Do not shake the tree to bring down nuts, since you may get a few unripe ones. Husk the nuts right away and let them air dry for at least two weeks.
Plant trees near a beehive for maximum pollination. In Hawaii, macadamia trees are often planted with coffee plants to increase production. Macadamia nut trees may not be available at local nurseries. Online tropical plant distributors may be the most viable option.
Do not store unhusked nuts for more than a day to avoid spoilage. Look out for pests such as macadamia root rot, trunk canker, dieback and flower blight. Macadamia trees are also susceptible to many pests, including the ambrosia beetle, broad mite, longhorned grasshopper and Hawaiian flower thrips.