When is the best time to harvest macadamia nuts?
Written by
Olivia Mitchell
Reviewed by
Prof. Martin Thorne, Ph.D.The successful growth of macadamia trees is ultimately determined by the proper timing of harvest. The nuts should be ripe when their husks split naturally and their shells turn a deep brown. I have seen impatient growers in the orchards in Hawaii crack the green nuts only to find that they produced a bitter nut inside. The best thing to do is to wait until they drop daily without fail and collect them within 24 hours to avoid possible mold.
Signs of Maturity
- Husk split: 1/4 inch gap exposing shell
- Shell color: Uniform brown, not green or mottled
- Nut drop: 5-10% daily fall signals peak ripeness
Harvesting Techniques
- Daily collection: Use tarps or nut harvesters
- Drying start: Begin within 6 hours of picking
- Tool hygiene: Sanitize baskets to prevent fungus
Drying can make or break nut quality. Place the nuts on mesh racks in single layers and drying them at a temperature between 95°F - 104°F (35-40°C) is optimal. A neighbor stacked his trays and, as a result, developed mold on nuts that cost him 30% of his crop. Use fans for airflow. Shake and test for dryness; as long as there is no moisture involved, after 14-21 days, the nuts should rattle freely in their shells.
---Put dried nuts in vacuum-sealed bags, adding oxygen absorbers for preservation. Glass jars are fine for use every month, but for long-term storage, freezer-safe bags prevent nuts from turning rancid. For example, I harvested nuts in 2020 and stored them for 18 months at 0°F (-18°C) before they became rancid. Stay away from plastic buckets - they retain moisture that causes spoiling.---
Be like a hawk when it comes to humidity! Nuts that are above 60% relative humidity will begin to reabsorb moisture. Again, as a precaution, place silica gel packets in storage containers. A client ignored this and her "dry" nuts molded in about 4 weeks. Digital hygrometers ($15) can help take the guesswork out of this. You want to aim for 10-15% kernel moisture content.
Plan your harvesting with the weather. If you harvest drops during rainy days the nuts will absorb water thereby doubling your drying time. Check the weather reports and hurry to collect the nuts if rains are imminent. After harvesting, label each batch with the harvest date. Early-season nuts tend to taste sweeter than nuts harvested later. Share your harvest online and join #MacadamiaHarvest to connect with fellow macadamia growers around the world.
Read the full article: How to Grow Macadamia Trees: A Complete Care Guide
