Macadamia

Sun

Full sun for good nut production; tolerates light shade but crops less heavily.

Water

Keep the root zone evenly moist but never waterlogged, especially during flowering and nut development. Established trees tolerate brief dry spells, but drought reduces the crop.

Soil

Deep, well-drained, slightly acidic soil, ideally pH 5.0-6.5. Avoid compacted ground, standing water and strongly alkaline soil.

Height

30-50 ft (9-15 m)

Spread

20-40 ft (6-12 m)

Flowers

Late winter to spring; long, hanging clusters of small cream-white flowers.

Foliage

Evergreen. Glossy, leathery, dark green leaves, usually in whorls of three. Mature leaves usually have smooth or sparsely toothed edges; young leaves can be more sharply toothed.

Growth

Moderate in warm, moist conditions; slow in cool climates.

Care needed

Medium

• Pollinators
• Heat tolerant
• Wildlife
• Fragrant
• Edible

Northern hemisphere months. In Australia, shift them by six.

Difficulty

Hard

Toughness

Needs looking after

Pick your zone, country, light and whether you have pets.

1. Planting day

   7 ft (2 m)

2. After 1 year

   8 ft (2.4 m)

3. After 2 years

   9 ft (2.8 m)

4. After 3 years

   10 ft (3.2 m)

5. After 5 years

   13 ft (3.9 m)

About 26 years to full size.

From a typical nursery size, at an average rate for this kind of plant. A rule of thumb, not a forecast.

Cats and dogs

Toxic

Native to

Australia

Growth rate

Slow

• Plant in a sunny position sheltered from strong winds, leaving room for the mature crown.
• Water deeply during dry weather, particularly while young and from flowering through nut filling.
• Spread organic mulch over the root zone, keeping it clear of the trunk.
• Feed lightly with a low-phosphorus fertilizer suitable for Australian native plants; avoid heavy applications of manure or high-phosphorus feeds.
• Protect young trees from frost with horticultural fleece or frost cloth, and avoid frost pockets.
• Choose a grafted tree of a locally suitable named cultivar for earlier, more predictable cropping; a compatible second cultivar can improve yields.

Pruning. Train young trees to a strong framework with well-spaced branches, removing narrow forks and damaged growth. After harvest, prune established trees lightly to remove dead or crossing branches and control size; avoid heavy topping.

Collect mature nuts after they fall naturally, usually from late summer through winter depending on climate and cultivar; gather them frequently rather than picking green nuts from the tree. Remove the outer husks promptly, dry the nuts thoroughly in a warm, airy place, then use a macadamia nutcracker to open the hard shells. Grafted trees commonly give a worthwhile crop about 4-7 years after planting;

Late winter

Protect young trees during cold spells and check that winter rain drains freely.

Spring

Plant after frost risk has passed, refresh mulch and apply a light low-phosphorus feed.

Spring

Keep soil moist during flowering and avoid insecticide sprays while bees are visiting.

Summer

Water deeply through dry periods and check developing nuts for insect damage.

Late summer to winter

Collect fallen nuts regularly, remove husks promptly and dry the nuts before storage.

After harvest

Remove damaged or crossing branches and lightly thin crowded growth if necessary.

• Use as a productive evergreen canopy tree in a spacious edible garden.
• Plant as a specimen in a sheltered lawn, allowing space beneath it for nut collection.
• Combine with subtropical foliage plants around the outer canopy for a layered garden.
• Include in a frost-free food forest, keeping its trunk and harvest area accessible.

Garden styles it suits: Australian native, Food forest, Backyard orchard, Edible landscape, Tropical and Homestead.

Plant it with: Pineapple, Ginger, Turmeric and Lemongrass.

Wildlife: Flowers provide nectar and pollen for bees and other insects. Nuts attract rodents and, in Australia, cockatoos, which can remove much of the crop.

• Root rot in wet soil: improve drainage before planting, keep mulch away from the trunk and avoid frequent shallow watering.
• Yellow leaves on alkaline soil: check soil pH and drainage; use chelated iron if iron deficiency is confirmed rather than adding more general fertilizer.
• Nut borers in susceptible regions: collect damaged and fallen nuts promptly, remove old husks and seek local advice on correctly timed controls.
• Poor nut set or premature nut drop: maintain moisture during flowering and nut filling, protect flowers from frost and consider a compatible second cultivar.

Macadamia nuts are toxic to dogs and can cause weakness, vomiting, tremors and overheating; contact a veterinarian promptly after ingestion. The edible kernels are not known to be toxic to people, though they can cause serious nut allergies. Toxicity in cats and horses is not well established, so do not feed them nuts or husks. Shells can cause choking or digestive blockage if swallowed.

• Rough-shell macadamia (Macadamia tetraphylla)

  Usually has leaves in whorls of four with more strongly toothed margins, pinkish flowers and rougher nut shells. Commercial hybrids can have intermediate features.

• Gympie nut (Macadamia ternifolia)

  Generally has smaller leaves and much smaller, bitter nuts. Its nuts contain cyanogenic compounds and are not edible; do not identify edible macadamias by leaf shape alone.

Macadamia honours the Scottish-born Australian physician and politician John Macadam, while integrifolia means entire-leaved, referring to the usually smooth margins of mature leaves.

Propagation. Fresh seed germinates in warm conditions, but seedlings vary in nut quality and take many years to crop. Grafting onto seedling rootstocks is the usual way to preserve a cultivar; buying a grafted nursery tree is the most practical option for a home garden.

Accepted botanical name

Macadamia integrifolia

In the US and Canada

Introduced in Puerto Rico.

Native range

New South Wales and Queensland.

Sources: GBIF (CC BY 4.0), USDA PLANTS and Trefle (CC BY 4.0). The care and design notes are LandscapeGPT's own.