Macadamia

Macadamia is grown in dedicated orchards of grafted cultivars selected for kernel quality, nut retention, and disease tolerance. Trees are slow-growing and long-lived, typically taking several years to reach significant bearing.

Commercial production is concentrated in a relatively small number of subtropical growing regions worldwide, reflecting the tree’s narrow climatic tolerance compared with many other tree nuts.

Family

Proteaceae

Genus

Macadamia

Principal species

Macadamia integrifolia; Macadamia tetraphylla; commercial hybrids of the two

Growth habit

Evergreen tree bearing racemes of flowers followed by a hard, globose nut in a fleshy husk

Macadamia is native to subtropical rainforest areas of eastern Australia, where it was used by Aboriginal peoples long before European settlement. Commercial breeding and orchard development began in Hawaii in the early twentieth century, which for decades led global production.

Australia, South Africa, Kenya, and Hawaii are now among the leading producing regions, with additional plantings in other subtropical countries. Production statistics are compiled by FAO and national agricultural agencies.

Macadamia requires a subtropical to tropical climate with well-distributed rainfall and moderate temperatures; it has little tolerance for frost, which can damage flowers, young growth, and even mature trees in severe cases.

Trees are grown on well-drained, slightly acidic loams and sandy loams. Shallow or poorly drained soils increase the risk of root disease and restrict the tree’s relatively shallow root system.

• Grafted cultivars selected for kernel recovery, nut retention, and regional disease tolerance
• Windbreaks commonly used, since macadamia flowers and immature nuts are vulnerable to wind damage
• Canopy management to maintain light penetration and ease mechanical harvesting
• Extended orchard establishment period before trees reach significant commercial bearing

Nitrogen supports canopy growth, while potassium is closely tied to nut fill and kernel development in macadamia, making its supply a key consideration in orchard nutrition programs.

Consistent moisture during flowering and nut development supports yield and kernel quality, and irrigation is widely used in drier production regions or during periods of low rainfall.

Irrigation scheduling is based on local evapotranspiration estimates and soil moisture monitoring, since both prolonged drought and waterlogging can harm tree health.

Phytophthora root rot is one of the most significant diseases of macadamia, particularly on poorly drained sites, and husk and stem anthracnose can affect nuts and young growth under humid conditions. Thrips can scar developing nut husks, and weevils are documented pests affecting nuts in some producing regions.

Mature nuts drop naturally from the tree and are collected from the orchard floor, typically by mechanical sweepers in commercial operations, then dehusked and dried before cracking and grading.

• Whole and processed kernels used as a premium snack nut, raw or roasted
• Confectionery and baking ingredient
• Macadamia oil pressed from kernels for culinary use
• Shells used in some regions as fuel or mulch