Macadamia walnut: the tropical delight

When we think of Hawaii, we think of beautiful beaches, warm sand, hula dancers and flower leis. And some of us also think of the macadamia walnut!

This beautiful, graceful evergreen produces an oily and rich nut that has been used as food in tropical climates for generations. However, what most of us don't realize is that they are more Australian than Hawaiian. Maybe we should say "g & # 39; day, mate" when we dip into one of those greasy delicacies nuggets … well, if it didn't take so much work to get into them.

The macadamia is a tough nut to crack and takes almost 300 pounds of pressure per square inch to break the shell. But we love them, hard to crack or not. They are used in a variety of dishes, are covered with chocolate, and are considered a tropical delicacy regardless of where they come from.

So let's talk everything about the beautiful macadamia walnut and how you can make these delicious delicacies!

Get a macadamia walnut

Good products for growing macadamia nuts:

Brief instructions on care

Macadamia nut treesMacadamia trees can reach a height of up to 40 feet. Source: Big Scout Project

Common Name (s) Macadamia, Queensland Nut, Bush Nut, Maroochi Nut, Bauple Nut, Hawaii Nut
Scientific name Macadamia integrifolia, Macadamia ternifolia, Macadamia tetraphylla
Months of harvest September to April
light Full sun, but partially tolerates sun in very hot climates
Water: Even watering evenly, more if the tree is very young
ground Rich, fertile clay soil – slightly acidic
fertilizer Balanced fertilizer twice a year, if possible a little less nitrogen
Pests Thrips, mites, scale insects, macadamia nut drills, stink bugs
Diseases Anthracnose, cancer

All about macadamia nuts

Although the macadamia tree is a popular crop in Hawaii, it actually comes from northeastern Australia. The tree is also grown in Africa, Asia and Latin America, as well as in the warm climates of Florida and California in the United States.

The macadamia tree belongs to the Protaceae family. Although the tree grows slowly, it will continue to produce for many years as soon as it bears fruit.

The foliage is a strong, deep green hue with elongated leaves with blunt tips and spiky, jagged edges. These leaves develop in groups of three to six, but almost never develop individually. When it blooms, its flowers grow on long ears, called grapes, each with between one hundred and one hundred and fifty flowers. The average tree produces about 2500 flowers in a certain flowering period.

Trees take seven to ten years to start producing harvestable nuts. The tree grows to a height of between 7 and 40 feet, although those used in commercial growing are usually kept short to facilitate harvesting.

Its nuts develop in a round and hard wooden bowl. This shell is about five times harder to crack than a hazelnut and has a variety of uses.

Bowls are often burned at extremely high temperatures to produce activated carbon for applications such as water filtration. They can be ground to produce a fertilizer for the tree itself, or used as mulch. They are also used when grilling in the pit, as the burning mussels do not give the food any unpleasant flavors. Occasionally, they are used to make a form of chipboard that is particularly moisture-resistant and prevents warping. And of course they make excellent biochar.

The real festival lies in these shells. The macadamia nut itself consists of almost 80% oil, which makes it an extremely high-calorie, aromatic nut. There is usually only one nut per shell, but occasionally two can form. These delicious nuts are rich in fiber, monounsaturated fats and are considered to be foods with a low glycemic index.

Other names for the macadamia nut are bush nut, Queensland nut, Hawaii nut, Bauple nut or Maroochi nut.

Types of macadamia

Flowering macadamiaDuring flowering, macadamia grapes can have dozens of flowers per stem. Source: Tatters

There are three types of macadamia nut trees that produce edible nuts. These are Macadamia ternifolia, Macadamia integrifolia and Macadamia tetraphylla.

  • Macadamia integrifolia comes from Queensland, Australia. It has white to pink flowers with woody, rounded fruits. The leaves are quite long with serrated edges.
  • Macadamia ternifolia is a smaller, multi-stemmed tree that grows up to 26 feet tall. This also comes from Queensland, Australia, with leaves that are dull from above and pale from below. It has pink petals that are 6-8.5 mm long.
  • Macadamia tetraphylla is a hard but small tree. The tree native to Australia usually occurs in rainforests or along borders and streams where the soil is most fertile.

A fourth macadamia tree, Macadamia jansenii, also occurs in the wild in Australia. However, the nuts are poisonous and are therefore normally not grown.

There are many varieties of macadamia nuts, but here are some of the most common.

  • Beaumont is a hybrid of Macadamia integrifolia and M. tetraphylla. It has bright pink flowers that appear on long clusters with vibrant, reddish leaves. This variety also has grape-like grapes that can end up leading to branches. Macadamia nuts do not fall when they are ripe, but this variety produces nuts that are easier to crack.
  • Maroochy is a pure M. tetraphylla variety, which is produced for its rich taste, healthy harvest and light pollination of the "Beaumont".
  • Fame is a hybrid variety of M. integrifolia and M. tetraphylla. As a spreading macadamia tree, it bears the highest yields. However, the nuts don't have much taste and are very thick-skinned.
  • Nelmac II comes from South Africa and is a hybrid variety of M. integrifolia and M. tetraphylla. It has a sweeter taste. Many people enjoy the uncooked seeds because of their sweetness. It is known for its pollination of "Beaumont" and provides delicious nuts.


Immature macadamia nutsWhen immature, the outer hull is green and blends into the foliage. Source: eekim

Planting macadamia nuts is relatively easy. But it will take years for them to grow and develop before they produce delicious treats. Find out how you can maintain them both during and after development!

When to plant

Macadamia seeds should be planted indoors from late autumn to early winter. This gives them enough time to germinate before spring. When the spring weather warms up, new seedlings can be gradually hardened to outside temperatures. However, care should be taken not to expose them to cold, as they are vulnerable at a young age.

Young grafts can also be planted out in spring, but after the last chance of frost has passed. Older trees can take a little cold and excessive heat, but young trees are at risk of frost damage or leaf burns.

Where to plant

Choose a place where the sun is shining all year round, but is protected from strong winds. While a ripe macadamia can be a very effective wind protection, there is a risk that its flowers will be damaged by strong winds. If you grow them for their nuts, you don't want these long clusters of flowers to be damaged when they appear!

Macadamias grown in containers need space for healthy root development. Make sure the size of the pot matches the height and age of the tree for good growth.

How to plant

When planting in the soil, loosen the soil in a circle of at least 3 to 4 feet around the planting area and at least 3 inches deep. Make sure your soil drains away excess water and change it if necessary to improve drainage.

Most Macadamia integrifolia trees arrive in a pot when you buy them, and any plants you get from seeds are also potted. Carefully take your tree out of the pot and check the roots to make sure they don't circle. If this is the case, open the root mass slightly with your fingers.

Plant your trees at the same depth that they were planted in the container. Do not plant them deeper than before as this can lead to stem rot. Your tree will grow in place for a while, so you want to make sure it stays healthy.

Plants that are placed in containers should have a container that is large enough to handle their root ball. Open the roots by hand again and examine the size. Then select a container that matches the size of your tree at that time. You may need to repot it in the future to make more space.

Macadamia Care

Macadamia in bloomThe macadamia can produce thousands of flowers per flowering period. Source: Tatters

Growing macadamia nuts doesn't take a lot of time and effort, but annual maintenance is required. It is important that your tree remains healthy. Let's look at some care tips that will help you.

Sun & temperature

When growing macadamia trees, the ideal growing areas are between 9 and 11. This offers the right annual climate and the least risk of frost or frost for your tree. They can be grown outside of these regions, but may not be as efficient.

Full sun conditions are ideal for your tree. If you have scorching summers, penumbra can also work as long as the tree has a good amount of morning sun.

While the ideal growth temperature for your plants is between 65 and 85 degrees, they can tolerate periods above or below.

Temperatures that are constantly above 95 degrees can reduce the harvest of macadamia nuts because the tree can be exposed to heat. An established tree planted in the ground can better deal with hotter climates if its roots go deeper. Container plants do not have this option. Therefore, make sure that all trees grown in containers remain hydrated.

If the temperature drops below 45 ° C, your tree may suffer. Provide protection by wrapping the trunk in a blanket or a commercially available tree bag. Trees that are less than 3 years old are most at risk and should be fully packaged. However, care should be taken to keep the bag away from the foliage by using piles as additional support for the bag.

Water & moisture

Uniform and regular watering is important for the cultivation of macadamia nuts. This is particularly important in certain phases of the development cycle. As soon as the nut begins to form, water is required to ensure that the nut is plump and aromatic. Too little water during this time leads to an inferior nut set.

A vegetative growth phase occurs in late spring and summer months. During this time, water is also required to ensure that the plant has enough moisture to develop leaves. Younger trees need more water than mature ones because they grow much faster.

If possible, try watering early in the day. For the first few years, a 5-gallon bucket of water that is slowly applied around the root area every few days during the hot months is a good amount. Drip or watering irrigation is also an option, as long as you ensure that the tree gets evenly and evenly moist.


Macadamia nut trees grow best in deep, loamy, well-drained soils. They also prefer a slightly acidic pH of 5.0-6.5. As they grow in other soil types, they tend to be less vigorous. Soils with a high content of natural salts can also have a negative effect on the growth of the tree.

Trees will also appreciate mulching as it helps prevent moisture loss. Mulching can be very helpful and prevent competitive weeds. The macadamia shells themselves can be a very effective mulch in a 3 to 4 inch deep layer. Do not place the mulch directly against the trunk and leave a space of at least a few centimeters around the trunk to protect the trunk.


Macadamias in the hull on treeBefore maturing, the outer hull is split to expose the mother trapped inside. Source: clasping walnut

Slow growers will find that your macadamia tree is fairly undemanding in terms of fertilizer. A citrus mixture or fish emulsion that contains no more than 1% nitrogen can be used twice a year. Fruit tree formulas can also work provided they are in the correct nitrogen range.

Aged manure or compost can be spread instead of at least one of the annual fertilizer doses, provided that it is nutrient-rich enough.

Apply fertilizer early in the spring when new growth begins and then again in midsummer. Do not fertilize in the autumn or winter months.


Regularly prune the tree by removing unhealthy or dead branches and branches that grow inwards. This trimming helps the air flow, prevents root rot, keeps the tree at the desired height and gives your tree a beautiful shape.

The cut can be done at any time, but the best time is in May or June after the harvest. Use either sterilized pruning shears or sterile pruning shears.


Macadamias reproduce easily from seeds, but it can take 8-12 years for the tree to harvest. In addition, depending on the variety grown, the trees may not be as strong as their parents.

A more consistent form of propagation is grafting, but macadamia nut trees are often difficult to graft. A simple whip transplant technique is the most common, but side transplants are also effective. Since the tree produces hard wood, grafting macadamias is best left to kindergarten staff.

Softwood cuttings can be rooted with the use of root hormone. This is more practical for home builders.

Harvest & storage

Macadamia walnutThe macadamia walnut produces rich, delicious nuts that we all like to eat. Source: Paloetic

So you grow macadamia nuts. How do you know when they started producing ripe nuts? More importantly, when and how should you harvest and store your hard-earned macadamias? Let's talk about it.


Ripe macadamia nuts fall from late autumn to early spring. With some varieties, you may need to poke the nuts with a shopping cart to make them fall. Shaking can also cause unripe nuts to fall. Avoid shaking the branches to encourage them to descend.

Place a tarp at the base of the tree to catch nuts, or pick them up off the ground when they fall. A daily trip to collect ripe macadamias should bring you a substantial supply, as the average tree at 10 years old can produce between 30 and 50 pounds of nuts.

The outer shell that surrounds the shell should dry out and turn brown before it falls to the floor. Remove the outer shell, leave the shell and its nut in place and let them dry in a dry place without sunlight for 2-3 weeks. Once you have air dried them, place your nuts in the shell in a dehydrator or oven at 100-115 degrees Fahrenheit for 12 hours, stirring occasionally, being careful not to cook.

Once fully dried in this way, the hard shells can be cracked to extract the nut meat.


After drying, your ripe macadamias can be roasted or left raw. Macadamias can be stored or frozen in airtight containers at temperatures between 40 and 65 degrees.

To roast your nuts, place peeled nuts on a tray and spread them on top. Avoid stacking them more than 2 deep. Roast in the oven for 40 to 50 minutes, stirring occasionally. They may or may not be salted before storage (as desired). The nuts produce enough natural oils, so you shouldn't need oil to fry them.


Macadamia nuts in shell and bodyThese delicious nuts are hidden in a very hard shell covered with a shell. Source: RaeAllen

As beautiful as macadamia trees are, they are still prone to pests and diseases. How to keep your plants free from most pests and diseases as well as most other macadamia problems!

Growing problems

A heat wave at the wrong time can reduce the potential harvest. This is especially true if it occurs during flowering. Similarly, strong winds can reduce harvests if they hit during flowering. While you can't stop the intense heat or strong wind, offering protection from the wind the first time you plant it is an option. Additional pouring over high heat can slow down the nut breakdown.

Avoid watering your trees. They like water, but if the soil is muddy or too damp, it can lead to root rot.


Very few pests are likely to be found on macadamia in the United States. Those who occur are more likely to be in the harassment category.

Thrips can inhabit the flower-decorated grapes of your plant. These annoying little pests eat plant juices and can reduce the harvest. You can continue to live on the shell and also feed on it. Horticultural oil applications should reduce their number.

Mites can also inhabit the shell around your nutshells, and they will eat them and leave the nut open to environmental risks. Broad mites can also feed on the flowers, reducing the nut set. As with thrips, horticultural oil reduces their number.

Scale insects can build on stems. Like thrips, these are juice suckers, but they rarely cause serious damage if they are on only a few leaves. You can simply cut off infested leaves. Horticultural oil will also reduce or slow their development.

The Macadamia nut drill is a moth larva that can seriously damage immature nuts before their hard shells form. These caterpillars eat both the leaves and the fruits themselves and can cause serious damage over time. Larvae are eliminated by using Bacillus thurigiensis.

Finally, that stinking beetle is a common pest … but also a blessing if it is the right variety. Some forms of stink bugs feed on the other pests, but not on the tree. The risk is if your stink bugs are more interested in the macadamia itself. If you start to see yellowed spots or chewed leaves and notice flat, bug-like winged insects, this is your culprit. Neem oil works against them early on, and horticultural oil can also be effective if it works less than neem.


Anthracnose can infect leaves and nuts in damp areas. This fungal disease can be treated by spraying the leaves and forming nut shells with a liquid copper fungicide. If only a few leaves show signs of anthracnose, you may be able to easily remove them with a light cut.

If the stem is damaged by a weed killer or other injury, it can develop cancer. These cancers are generally fairly harmless, but certain types can cause stem rot. Avoid damaging the trunk by keeping weeds and grass away and mulching just under the tree canopy to reduce weed growth.

frequently asked Questions

Q: How long does it take to grow a macadamia nut tree?

A: If you start with seeds, it can take 8-12 years to produce consistently.

Q: Do you need two macadamia nut trees?

A: You need at least two trees for cross-pollination. Most varieties of macadamia are not self-pollinating and cannot produce fruit without a nearby pollinator.

Q: Are macadamia nuts toxic to dogs?

A: Yes, they are. Ingesting more than 2 grams of macadamia nuts per kilogram of body weight can cause a variety of symptoms, including vomiting, weakness, fever, tremors, or depression.

The green thumbs behind this article:
Lorin Nielsen
Lifetime gardener

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