Macadamias

Macadamias

Article originally published by: Kiwi Gardener

Hannah Zwartz enables Kiwi gardeners to grow this nut delicacy.

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The first time I saw a macadamia tree was in, of all places, Wellington. Several metres tall and cropping well, the tree was tucked into a sunny, sheltered, north-facing corner of a small backyard on Epuni Street, in Aro Valley.

Back in the 1980s this seemed (and was) incredibly unusual and exotic. These days, macadamias are more widely available and, as the Aro Valley tree goes to show, these sub-tropical lovelies can be grown in less-than-tropical sites, as long as gardeners meet their needs: in particular, shelter from wind and frosts.

Macadamias are one of the few plants native to Australia that are grown there as commercial food crops today – though the biggest plantations are in Hawaii. They originate in the rainforested mountains of the southern Queensland coast and, as anyone who has visited the Gold or Sunshine coasts will know, this area is warmer than most parts of New Zealand. Yet they grow in Aotearoa both as a backyard tree and, in northern areas – the Bay of Plenty and Northland in particular – as a commercial crop. I’ve seen macadamias growing well as far south as Marlborough and the Buller region of the South Island’s West Coast.

Wanting to grow a macadamia? You’ll need good shelter. Mature trees will survive a light frost, but young ones will need protection.

They are not too fussy about soil – though it’s always good to improve it with compost – as long as it’s well-drained and doesn’t stand in a soggy condition. According to the NZ Macadamia Society, if tamarillos will grow that’s a good indication conditions will be good for macadamias.

Macadamias are big trees, growing as high as 10m or more. But many types are upright, almost columnar in habit, making them easier to fit into a small garden than a more spreading tree. If pruning is needed, winter is the best time to do it, straight after the nuts have been harvested.

Physically, macadamia trees resemble rewarewa (to which they are related, both being in the wider protea family). Leaves are long, shiny and waxy, usually serrated. The tree I remember from Aro Valley was cropping well without another macadamia in sight, but the NZ Macadamia Society recommends planting more than one variety for maximum pollination.

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There are two main species – Macadamia integrifolia, with creamy-yellow flowers, and the spinier M. tetraphylla, whose young leaves and flowers are bronzy-pink. These two species, however, have produced numerous crosses, which vary in spininess of leaves, colour of flowers, size of nut and thickness of shell.

The flowers, and later the nuts, hang down in clusters beneath the leaves. Nuts are almost spherical with a hard, glossy casing, which can be difficult to crack. But it’s worth the effort as inside is creamy, sweet, crunchy flesh rich in good fats and essential trace elements and minerals.

Hard though they are to crack (sometimes demanding a specially built nutcracker) the nuts are still somehow attractive to rats, who nibble through the shells leaving tell-tale circular holes. So rat control can be an issue, especially if your trees are ‘droppers’, as opposed to ‘clingers’, on which ripe nuts wait to be picked – according to Anne and Paul Robin of Ohiwa Macadamias, Bay of Plenty.

Nuts ripen over winter, but depending on your tree’s variety, and which part of the country you live in, harvest could be any time between May and October. Ripe nuts need to be collected every day or so to keep ahead of the rats, and to avoid them being spoiled by wet ground conditions. The outer husks need to be removed to allow the hard inner shells to dry.

Macadamias are delicious straight from the shell. For a sweet treat: try dipping the nuts in dark chocolate; adding them with marshmallows to a rocky road mixture, or making white chocolate and macadamia chip cookies. They can be equally good in savoury recipes – added to salads for a crunchy texture, or in rich creamy macadamia basil or parsley pesto, with macadamia nuts substituted for pine nuts

In a nutshell:

  • Macadamias need good shelter and frost-free locations.
  • They like similar growing conditions to tamarillos if tamarillos will grow, macadamias should, too.
  • Trees start bearing within three to five years.
  • They are often alternate bearing (cropping more heavily every second year).
  • A mature tree can bear up to 8kg of nuts.