Growing macadamia nuts outside is possible only in frost free region. Learn how to grow macadamia nuts tree in this article.
USDA Zones — 9 – 11
Propagation Method — Seeds, vegetative propagation
Difficulty — Moderate
Soil Type — Acidic to slightly acidic
Macadamia tree is native to Australia, the tree grows up to anywhere between 2 – 12 m ( 7 to 40 feet tall). It is mainly cultivated for its fruits. Only two species of macadamia produce edible nuts: Macadamia integrifolia and Macadamia tetraphylla. Both are natives of eastern Australia, but also thrive in Hawaii, Southern California and many other subtropical and tropical regions outside USA where winters are above freezing level and the rainfall is consistent. Macadamia trees are bushy, evergreen and can be grown outside or in large containers. If cultivated properly, macadamia nuts trees start to produce fruits in 4 to 6 years after planting.
Although propagation from seeds is easy but they are commercially not propagated from seeds because it take up to 12 years to start producing nuts. They are usually propagated from cutting, grafting and budding.
Buy a grafted macadamia tree from your nearby nursery. Plant it in same depth in which it was grown. Firm the soil around the roots to eliminate air spaces and water deeply after planting to help lessen the shock of transplanting.
Select a location in your yard that gets full sun but get sheltered from the wind. South or West side of a garden that is less windy is suitable.
Requirements for Growing Macadamia Nuts
Macadamia nuts are slow growing and in clay rich soil they grow more slowly. Before planting also make sure that your soil is well draining and deep. If it is not, amend it using perlite or sand. Keep pH level around 5 – 6.5
Macadamia is a tropical tree, it requires full sun to grow and produce healthy fruits.
Keep the soil of macadamia tree slightly moist. Water young macadamia tree regularly. Once the plant matures water it once a week during the growing season and every other day during the period of drought and summer.
Macadamia Tree Care
Do mulching to preserve moisture as growing macadamia nuts tree requires slightly moist soil. Mulching also prevents the competitive weeds.
Fertilize with 1% nitrogen fertilizer twice a year, in the beginning of growing season and in mid season. Macadamia tree grows slowly, so you do not need a lot of nitrogen.
If your soil is rich you do not need to fertilize often as excess fertilization can damage the tree.
Prune in early spring with pruning shears, as you do with an apple tree, to promote a single strong trunk and 6 to 8 horizontally growing scaffold branches spaced evenly along the height of tree. Clip off the vertically growing shoots because they will not produce nuts and will sap the vigor of the tree. Also prune off dead and damaged wood.
Pests and Disease
Healthy macadamia tree is usually pest free but thrips, mites and scales might attack it, but mostly they are deterred by tree itself. Use of organic pesticide is recommended in case of large infection.
Collect macadamia nuts when their skin begin to crack. Shell them within 24 hours of harvest to prevent mildew. Keep in mind that the hulls will be more difficult to remove once they have dried.