Guide to Macadamia

Below are our recommendations for the growing and processing of macadamias from the experience we have gained from many years of both growing and processing of nuts as the largest manufacturer of nut processing equipment in New Zealand.
Trees: There are 2 main varieties of Macadamia trees Integrifolia (also known as dropper) and Tetraphylla (also known as stickfast). There are pros and cons to both varieties and its best to look at what will suit your site and harvesting conditions to choose the best variety. A few things to consider are:
  • Is it dry underfoot during harvesting, so a mechanical harvester won’t rut the ground?
  • Do you want to harvest one tree at a time, or do you want to harvest the entire orchard every few days as the nuts drop?
  • Is your site on a steep slope so nuts can roll away?

Tree spacing: We recommend 6 x 8 meters as a minimum so there is adequate sunlight between the trees and a tractor or harvester can be easily driven between rows. This equates to around 160 trees per hectare.

Soil conditions: PH of 5.5 to 6.5 with free draining sandy or volcanic soils facing the sun and frost protection is a must especially with young trees, probably best practice to only plant in a frost-free environment to give young trees the best possible chance.

Kernel recovery: 30% off initial weight after harvesting as a rough guide with the remainder being husk and shell. For crop calculations we use 20kg of Nut In Shell (NIS) per tree once mature.

Harvesting: An easy way to check if your nuts are ready to harvest is to look at the inside lining of the husk after the shortest day of the year. When the lining has turned brown to about the same colour as the nut inside, the crop is ready for harvesting.
With droppers it’s best to run a mower through the orchard just before the harvest to get rid of any immature nuts the trees may have dropped early.

Post Harvest: The following is the same for all macadamia varieties once the nuts have been harvested.

  • De-husk between 24 and 48 hours after harvest for best results using the V-Twin Dehusker. The husks are now commonly composted off-site away from the orchard as they can contain many plant pests we don’t want to spread through the orchard.
  • Dry the nuts to below 10% moisture, this is normally done in 1 tonne drying bins with fan forced air as soon as possible to then use a secondary drying system of silos or dehumidifiers to drop the moisture further.
We recommend a NIS moisture level below 3% with 1.5% being ideal for both long storage and best crack out through the Twin Cracker.

After cracking: There are 2 main recognised methods of separating shell from kernel.

1: Feed the nuts through a colour sorter. This can be high cost but almost no labour is required and it’s easy to automate.

2: Feed nuts through a trommel and then hand sort on a conveyor belt, this option is low cost but requires a lot of labour.