Mature macadamia nuts will fall to the ground from late fall to spring. It's best to harvest the nuts that are already fallen, because shaking the tree will bring down immature nuts as well. You can expect about 30 to 50 pounds of nuts from a ten-year-old tree.
Dehusk the nuts; spread out to dry in a dark, dry place for 2 or 3 weeks. You can finish drying in an oven at the lowest temperature setting for about 12 hours, stirring occasionally, without cooking. Avoid excessive heat.
Store the nuts in a heavy plastic bag in a cool, dry area. Shells can be removed from the dry nuts with a nutcracker.
Read more about harvesting macadamia nuts.