How to Grow Macadamia Nuts Tree

Here are the best tips on How to Grow Macadamia Nuts Tree successfully in your backyard. Our comprehensive guide covers everything!

Don’t know How to grow macadamia nuts? The Macadamia tree is native to Australia and grows up to anywhere between 2-12 m ( 7 to 40 feet tall) and is mainly cultivated for its fruits. Keep reading this article to learn everything about Growing Macadamia Nuts.

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Macadamia Tree Information

The Macadamia tree belongs to the family Proteaceae. This family is primarily native to the Southern Hemisphere and includes various flowering plants, including many species of shrubs and trees.

The Macadamia tree is native to eastern Australia, specifically in the rainforests of Queensland and New South Wales. It is also commonly known as the Queensland nut tree.

Macadamia trees are medium to large evergreen trees that can reach heights of up to 40 feet (12 meters) or more. They have dense, glossy green foliage and produce pinnate leaves with multiple leaflets. The tree’s bark is typically rough and dark brown.

What Makes it Special? 

• Edible Nuts: The most famous feature of the Macadamia tree is its delicious and highly prized nuts. Macadamia nuts are known for their creamy texture, buttery flavor, and high oil content. They are often eaten raw, roasted, or used in various culinary applications, such as baking and cooking.
• Ornamental Value: In addition to their culinary value, Macadamia trees are often grown for their ornamental appeal. Their lush foliage and attractive appearance make them desirable landscaping trees in tropical and subtropical regions.
• Environmental Benefits:  Growing macadamia nuts trees can help protect soil and reduce erosion in their native habitats due to their extensive root systems. They also provide habitat and food for local wildlife.

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Propagating Macadamia Tree

Ways to Propagate Macadamia Trees

• Seed propagation
• Grafting
• Budding
• Air layering
• Cuttings
• Tissue culture

The Most Popular and Reliable Method: Grafting

Grafting is the most reliable method for propagating Macadamia nut trees because it preserves the desired genetic traits of the parent tree, ensures faster maturity, and provides consistent, known quality compared to growing from seeds.

Steps for Grafting Macadamia Tree

1. Select Rootstock and Scion Wood: Choose a healthy Macadamia tree as your rootstock and a scion wood with desirable characteristics for grafting.
2. Prepare Rootstock Plant: Trim the rootstock to your desired height, typically a few feet tall. Make a clean, diagonal cut on the rootstock stem just above the ground.
3. Prepare Scion Wood: Collect scion wood with 2-3 buds and a diagonal cut matching the rootstock’s cut.
4. Make Matching Cuts: Create a matching cut on the rootstock and scion wood to fit them together perfectly. Common grafting techniques for Macadamia include cleft grafting or whip-and-tongue grafting.
5. Secure Graft Union: Place the scion onto the rootstock, ensuring that the cambium layers (greenish inner tissue) align. Use grafting tape or rubber bands to secure the union tightly.
6. Protect the Graft: Cover the graft union with grafting wax or similar protective material to prevent drying out and infection.
7. Provide Optimal Conditions: Place the grafted plant in a controlled indoor environment with high humidity, ideally using a propagation chamber or misting system. Maintain stable temperature and light conditions to encourage healing and growth.
8. Monitor and Transplant: Monitor the graft for signs of successful union and new growth, which may take several weeks.

Once the graft has established and shows vigorous growth, you can transplant it to a suitable pot or location.

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Advantages of Grafting

• Genetic Consistency: Grafting ensures that the new tree inherits the exact genetic characteristics of the parent tree, including nut size, flavor, and disease resistance. This is especially important when Growing macadamia nuts because it guarantees desirable traits.
• Faster Maturity: Grafted trees tend to mature and bear fruit more quickly than trees grown from seed. This means you can start harvesting nuts sooner when you use grafted trees.
• Known Quality: When you graft a Macadamia tree, you are working with a known quantity. You can select a high-quality tree with proven nut characteristics, which may not be the case with trees grown from seeds where the quality can vary.

Note: It is always a good idea to buy a well grafted tree from a garden center to cut down the harvest time!

Choosing a Container for Macadamia

Macadamia trees can become quite large and have extensive root systems, so choosing an appropriately sized container is essential.

While you can start the plant in a small 10-12 inches pot initially, consider using a container of 16-22 inches for mature specimens, but that too will make it limited to just a foliage plant that might provide a little harvest. For nuts, you have to grow it in the garden.

Requirements for Growing Macadamia Nuts

Sunlight

Macadamia trees thrive in full sun. They require at least 6-8 hours of direct sunlight daily to grow and produce nuts successfully. Inadequate sunlight can lead to reduced nut production and weaker overall growth.

When Growing macadamia nuts indoors, ensure they receive sufficient light by placing them near a south-facing window or using supplemental grow lights if natural sunlight is limited.

Soil

Macadamia trees prefer well-draining soil with a slightly acidic to neutral pH level. They thrive in soil that is rich in organic matter. A loamy or sandy soil type with good drainage is ideal. Macadamia trees thrive in soil with a pH level between 5.5 and 7.0.

Avoid heavy clay soils that can become waterlogged, as Macadamia trees are susceptible to root rot under such conditions. Adding organic compost to the soil can improve its texture and nutrient content.

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Water

Macadamia trees have moderate water requirements. It’s essential to keep the soil consistently moist but not waterlogged. Water deeply and infrequently rather than shallow, frequent watering.

Adjust the watering frequency based on environmental conditions and the tree’s growth stage. In hot weather, you may need to water more often.

Temperature

Macadamia trees are sensitive to frost and cold temperatures. They should be planted in areas where the minimum winter temperature does not drop below 24 to 28°F (-4 to -2°C). Macadamia trees grow best in temperatures between 65 and 90°F (18 to 32°C).

These temperatures promote healthy growth, flowering, and nut production.

Macadamia trees are native to regions with high humidity, so they appreciate a moderately humid environment. When Growing macadamia nuts indoors or in a dry climate, consider increasing humidity levels around the plant.

Macadamia Tree Care

Fertilizer

Macadamia trees benefit from a balanced fertilizer regimen to promote healthy growth and nut production. A slow-release, granular fertilizer with a ratio of NPK (nitrogen, phosphorus, and potassium) tailored to fruiting trees (such as 8-3-9) is suitable for Growing macadamia nuts. 

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Apply fertilizer evenly around the tree’s drip line, avoiding direct contact with the trunk. After fertilizing, water the area thoroughly to help nutrients penetrate the soil.

• Spring (Early): Apply fertilizer in early spring as new growth begins to support healthy foliage and flowering.
• Summer (Early): Fertilize again in early summer to encourage nut development and overall tree vitality.
• Late Summer to Early Fall: Reduce or withhold fertilization during late summer to early fall, allowing the tree to prepare for dormancy in the winter months.

Pruning

Perform pruning during the late winter or early spring when the tree is in its dormant phase. This minimizes stress on the tree and reduces the risk of disease transmission.

Use clean and sharp pruning tools, such as pruning shears or loppers, to make clean cuts and minimize damage to the tree. Begin by removing dead, damaged, or diseased branches. These can be a source of pathogens and should be pruned back to healthy tissue. Thin out the canopy by selectively removing crowded or crossing branches.

Pests

• Macadamia Nut Borer (Cryptophlebia ombrodelta): Larvae bore into nuts, causing damage to the fruit and reducing nut quality.
• Macadamia Felted Coccid (Eriococcus ironsidei): Feeds on sap and produces honeydew, leading to sooty mold growth on leaves.
• Stink Bugs: Pierce nuts with their mouthparts, causing damage and reducing nut quality.
• Scale Insects: Feed on sap, weakening the tree and excreting honeydew, which can lead to sooty mold.
• Aphids: Suck sap from leaves, causing distortion and curling of foliage.
• Macadamia Leafminer (Acrocercops chionosema): Larvae create serpentine mines within leaves, affecting photosynthesis.

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Diseases

• Anthracnose (Colletotrichum): Results in dark lesions on leaves and nuts, reducing fruit quality.
• Macadamia Fungal Canker (Neonectria spp.): Causes sunken lesions on stems and branches, potentially leading to dieback.
• Powdery Mildew (Oidium spp.): Forms a white powdery growth on leaves, affecting photosynthesis and overall tree health.
• Bacterial Blight (Xanthomonas campestris pv. translucens): Leads to water-soaked lesions on leaves and fruit, causing tissue decay.
• Macadamia Mosaic Virus (MMV): Affects leaves, causing mottled discoloration and reducing photosynthesis.

Harvesting Macadamia Nuts

Maturing After Propagation

• From Seeds: Growing macadamia nuts from seeds is a natural but time-consuming process. It may take five to seven years or even longer for seed-grown trees to bear fruit.
• Grafting: Grafted Macadamia trees tend to mature more rapidly than those grown from seeds. Typically, grafted trees can start producing nuts within two to four years after grafting, depending on the tree’s age at grafting and environmental conditions.

Days to Harvest

• It can take anywhere from 140 to 180 days (approximately 4.5 to 6 months) from pollination to full nut maturation. However, this timeline can be influenced by factors such as climate, weather conditions, and local growing practices.

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Signs the Fruit is Ready to be Picked

Here are some signs that indicate the nuts are ready to be picked:

1. Husk Splitting: As the nuts mature, the husks will naturally split open, revealing the hard shell inside. This is a clear sign that the nuts are ripe for harvesting.
2. Change in Color: Mature Macadamia nuts typically exhibit a change in color, shifting from green to creamy beige or brown, depending on the cultivar.
3. Sound Test: When gently shaking the tree or tapping a nut with a hard object, a mature nut will produce a dull, metallic sound, while an immature one will sound hollow.
4. Ease of Removal: Ripe Macadamia nuts are relatively easy to remove from the tree by gently twisting and pulling. If they do not come off easily, it’s an indication that they are not yet fully mature.

Storing Macadamia Nuts

Now that you know How macadamia nuts grow, here are some guidelines for storing Macadamia nuts:

• Shell Storage: Macadamia nuts can be stored in their shells for an extended period. Place them in a cool, dry, and well-ventilated area away from direct sunlight and moisture.
• Shelled Nuts: If you’ve removed the nuts from their shells, store them in an airtight container or vacuum-sealed bag to prevent exposure to air, which can cause them to become rancid. Keep them in a cool, dark place.
• Refrigeration: For longer-term storage, consider refrigerating or freezing shelled Macadamia nuts in airtight containers or vacuum-sealed bags to maintain their freshness.

FAQs

1. How Do Macadamia Nuts Grow?

Macadamia nuts grow on evergreen trees native to Australia. They develop in hard, woody pods and mature within 6-7 months.

2. Where Do Macadamia Nuts Grow?

Macadamia nuts primarily grow in regions with a warm, subtropical climate. Australia, Hawaii, California, and parts of South Africa are some of the main global cultivation areas.

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3. Do Macadamia Nuts Grow on Trees?

Yes, Macadamia nuts grow on trees known as Macadamia trees. These trees can reach heights of up to 40 feet and produce nuts within their hard-shelled fruits.

4. Where Do Macadamia Nuts Grow Map?

Macadamia trees are typically suited to USDA Hardiness Zones 10-11. You can find Macadamia nut growing regions on a USDA Hardiness Zone map. The USDA’s map categorizes areas based on their climate suitability for various plants, helping you determine where Macadamia trees can thrive.