Macadamia spp.

macadamia

Proteaceae

Eastern Australia (Queensland and New South Wales)

Attracts Pollinators

SunFull Sun

WaterMedium

HardinessZones 9–11

Overview

Macadamia spp. is a genus of four species of evergreen trees in the family Proteaceae, native to the subtropical rainforests of eastern Australia in Queensland and New South Wales. Trees grow 20 to 50 feet (6 to 15 m) tall with dense, spreading crowns and leathery leaves arranged in whorls of three to six, their margins smooth or spiny depending on species. Long, pendent racemes of small white to pink flowers appear in late winter and spring, followed by hard, woody fruits that split to release the round, cream-colored seed, the edible macadamia nut. M. integrifolia and M. tetraphylla are the species grown commercially for nuts, while M. ternifolia and M. jansenii bear bitter, inedible seeds; M. jansenii is critically endangered in the wild. The nuts are encased in an extremely hard shell. Trees grow in deep, fertile, well-drained acidic soil in frost-free climates and are damaged by hard frost and strong wind. The raw nuts are edible to people but are poisonous to dogs.

Native Range

Native to the coastal subtropical and tropical rainforests of central and southeastern Queensland and northeastern New South Wales, Australia. Wild populations are limited and several species are threatened by habitat clearing.

Suggested Uses

Grown as an orchard and nut crop in subtropical regions and as a shade or specimen tree in frost-free gardens and parks. The dense evergreen canopy is used for screening and shade. Trees combine with other subtropical species in large gardens.

How to Identify

Recognized by leathery leaves borne in whorls of three to six, often with spiny-toothed margins on young growth, and by long, hanging racemes of many small white to pink flowers. The fruit is a hard, green to brown follicle that splits along one side to reveal a single round, hard-shelled nut. Mature trees have a dense, rounded canopy.

Appearance

Size & Dimensions

Height20' - 50'

Width/Spread20' - 40'

Colors

Flower Colors

Foliage Colors

Fall Foliage Colors

Bloom Information

Bloom Period

~6 weeks

Winter Spring

Flowering occurs in late winter and spring, roughly August to November in the Southern Hemisphere, with long pendent flower racemes. Nuts develop over six to seven months and ripen from late summer into autumn. Trees can carry flowers and developing nuts at the same time.

Detailed Descriptions

Flower Description

white to pink

Foliage Description

green

Growing Conditions

Sun Requirements

SunFull Sun

Requires 6-12 hours of direct sunlight daily

• Full Sun: 6+ hours of direct sunlight

• Partial Shade: 3-6 hours of direct sunlight

• Full Shade: Less than 3 hours of direct sunlight

Soil Requirements

pH Range5.5 - 6.5(Neutral)

357912

Soil Types

loam sand

Drainagewell drained

Water & Climate

Water Needs

Medium

Frost Tolerance

tender

Time to Maturity

Begins bearing in four to six years; reaches full size in 10 to 15 years

Care & Maintenance

Care Guide

Grows in full sun in deep, fertile, well-drained soil with an acidic pH of about 5.5 to 6.5, in frost-free subtropical and warm-temperate climates. Young trees are tender and damaged by frost, while mature trees withstand light frost but not hard freezes. Steady moisture and shelter from strong wind support good growth and nut set, as the shallow roots and brittle branches are wind-sensitive. Trees begin bearing nuts in four to six years and reach full production in around ten to fifteen years. Few serious pests occur outside commercial orchards, where nut borers and felted coccid can be problems. The raw nuts are edible to people but contain compounds poisonous to dogs.

Pruning

Young trees are pruned to a single central leader and a framework of well-spaced branches. Mature trees need little pruning beyond removing crossing, damaged, or low branches to keep the canopy open for light and air. Pruning is done after harvest in late autumn or winter.