Macadamias are loved by everyone, and for good reason; they taste amazing, are full of good fats and antioxidants, lower bad cholesterol, raise good cholesterol and are good for the heart. These nuts can be eaten raw or roasted and are used in a variety of recipes both sweet and savoury. They are one of Australia’s most successful native plants developed commercially.
There are several native macadamia trees at Booyong and the most magnificent one is in the Kiwi fruit farm which will in time become a native food forest. The tree propagates naturally and you will find many new plants popping up when bushwalking in that area. We are uncertain what to do with them, as we have been advised by one person to let them go as they are, whereas another person recommended taking the new plants out and keeping them under control to prevent them from permeating the whole conservation area. We are thinking about making the walking track at the kiwi fruit farm a boundary and removing new plants that arise, ensuring they don’t cross the path and encroach too much within the conservation area.
In the short time we’ve been at Booyong it’s been interesting to witness how the change in weather and rainfall affects the production of both the pecan and macadamia nuts. They prefer distinct wet and dry seasons and grow on a large range of soils but prefer well-draining types; clay soil is prone to water logging and in wet periods root rot occurs (5-5.5 Soil PH). They don’t grow well in frost and don’t like temperatures over 38 degrees, because high temperatures reduce growth and increase early dropping of nuts.
Macadamias grow in either light shade or full sun. Late autumn is a good time to plant as it gives the plant plenty of time to get established before the summer months. Whilst this native plant propagates easily from seed and can be propagated from a cutting, a grafted plant is recommended as it will provide more nuts earlier. Trees should be mulched carefully so the mulch doesn’t reach the tree trunk and they also like a little bit of fertilizer every 2 months from September to May. When fertilising use a native or citrus plant product as they are sensitive to phosphorus.
The macadamia tree flowers in May and its flowers are pink or white spikes that hang from the inner branches of the tree. The flowers turn into nuts and take some 9 months to mature. The shells are hard but well worth the effort to break them (I’ve been known to use the vice in the shed – it works wonders). Nuts fall mid-February and continue through till August, and fallen nuts are often still in their husk which need to be removed and can be used as mulch.
After harvest, internal branches should be removed to open up the trees and allow air circulation.
We haven’t had much opportunity to cook with the nuts at Booyong as the birds and native bush rats seem to beat us to them, but we will persist and let you know how we go.
Macadamia bush nut – Botanical Name: Macadamia tetraphylla
This was the first Australian native food plant to be grown by non-indigenous Australians as a commercial crop. It’s a very hardy plant and easily grown along most of Australia’s east coast all the way down to Victoria.
This is a medium sized tree to 10m native to southern QLD and Northern NSW. The fruit is hard shelled, and the nuts fall from the tree when they are ripe. Flowers occur in September to November and nuts from December until March.
Propagation can be done from cuttings. If planting do so in full sun to part shade position in deep friable soil. It bears nuts in approximately 5 years. Our tree is well established and has medium frost tolerance which is beneficial. It’s beneficial to have two planted for best pollination but a single tree will set nuts.
The leaf of the bush nut is pointy on the end and the nuts are often singular as opposed to the other variety at Booyong (macadamia Integrifolia) which has bunches of macadamia nuts.
Macadamia – Botanical Name: Macadamia Intergrifolia
The second macadamia nut tree in the Food Forest is a small to large tree that bears decorative trusses of cream flowers, followed by edible, nutritious nuts. Unlike the Bush nut it has bunches of nuts and a curved leaf shape.
Macadamia integrifolia is a small to medium sized tree to about 15 metres with a bushy habit. The glossy leaves are oblong in shape to about 200mm long by 100 mm wide and often have wavy margins. Flowers are white and occur in pendulous racemes up to 300 mm long, usually in winter and spring. They are often hidden among the foliage. The fruits are globular and about 25 – 35 mm diameter. They have a hard, green outer layer and an extremely hard inner shell which protects the kernel.
Even if it did not produce an edible nut, Macadamia integrifolia would still be cultivated for its attractive, ornamental habit. It has proven to be hardy in a range of climates and soils but prefers good drainage and humus-rich soils. It will flower and set fruit in much cooler areas than its natural habitat. It is troubled by few pests and will tolerate moderate frosts.
Propagation from seed is relatively easy – the seed should be sown when fresh. Cuttings are also successful but vegetative propagation is usually carried out by grafting or budding of select forms onto seedlings.
It attracts bees and butterflies.