April 26, 2023
The Searles Gardening Team
Macadamia nuts trees are traditionally a large Australian native tree. Originally from the subtropical rainforests, they prefer a frost-free environment and plenty of water. Macadamia nuts are a bush tucker and varieties are available that are dwarf and can be grown in pots. Varieties that have smoother leaves with less prickles are also available to the home gardener.
These fruit trees are not for the impatient gardeners, as they can take over a decade to produce a full crop. After several years they do start to tease with yields, but it is not until they reach maturity does this significantly increase. Macadamia trees have been known to live for over fifty years and still be producing nuts. New cultivars are still being developed to produce a crop quicker but are not available to the home gardener.
Macadamia trees rely heavily on bees for pollination, if you already have a tree that flowers but does not bare much fruit then a lack of bees could be an issue. If the tree is planted in an area of strong winds this will reduce the number of bees as well. Plant them in a full sun position that is still sheltered from strong winds.
Maintenance will include giving them a hard prune after they finish fruiting and before they start the next cycle of flowering. This can assist in keeping them smaller so you can net the trees to stop birds from eating the fruit. Fertilising the trees will need to be regularly applied, Searles Fruit & Citrus Food is suitable for macadamia trees and apply as directed.
The main pest of macadamia trees is nut borer. There are insecticides for this pest but consider trying a biological control. The Trichogrammatoidea cryptophlebiae is a wasp from Africa which attacks the eggs of the nut borer and is now often used to control the pest without the use of chemicals. Since it attacks the eggs and not the adult the wasps need to be released at a set time. There are native wasps that also attack the eggs but are not commercially available. Removal of all old nuts and regular inspections of the forming fruit weekly will assist in the control of macadamia nut borer.
Generally, macadamia is a quick growing Australian native tree. Though it is a large tree, they can be heavily pruned to fit the garden situation or dwarf varieties can be grown in pots. The fact they produce a magnificent nut is a bonus for those who are willing to wait. Being a native, it is well suited to grow in frost free areas but check with our local nurseryman which variety is best for your region.