Harvesting walnuts primarily involves waiting for them to ripen on the tree and then dislodging them, typically by shaking, before collecting them promptly from the ground.
When to Harvest Walnuts
The ideal time to harvest walnuts depends on the variety and local climate, but generally occurs from late September through October. Knowing when your walnuts are ripe is crucial for a successful harvest.
Key Ripeness Indicators:
- Hull Splitting: The most reliable sign is when the green outer hull begins to split open, exposing the inner shell. This indicates the kernel inside is fully developed.
- Hull Drying: The hull may also start to turn yellow or brown and dry out.
- Ease of Separation: The hull should be easy to separate from the nut.
- Nut Color: The nut's inner shell will turn a dark brown color.
- Walnuts Falling: Some walnuts may naturally fall from the tree.
Expert Tip: To accurately assess ripeness across your entire tree, it's advisable to test walnuts from high up on your tree, as these typically ripen last and will therefore indicate the ripeness of the rest of your tree.
Harvesting Methods
Once the walnuts are ripe, they need to be removed from the tree.
1. Manual Harvesting (Shaking & Picking)
This is the most common method for home growers or smaller orchards.
- Shaking the Tree: Once ripe, you can shake walnuts loose from your tree. Utilize a pole or your hands to shake the walnuts free from the branches. For taller trees, a long pole with a hook or shaker attachment can be very effective.
- Collecting Immediately: After shaking, the walnuts will fall to the ground. It is crucial to collect them from the ground immediately to prevent damage from pests, moisture, or soil contact, which can stain the shells or degrade the kernel quality.
- Using Tarps: Laying tarps or old sheets under the tree before shaking can make collection much faster and cleaner.
2. Mechanical Harvesting
For larger commercial operations, specialized machinery is used to expedite the process.
- Tree Shakers: Large hydraulic shakers grasp the tree trunk and vibrate it vigorously, causing thousands of walnuts to fall quickly.
- Sweepers and Harvesters: Following the shakers, machines sweep the nuts into windrows and then pick them up, separating them from leaves and debris.
Post-Harvest Steps
Harvesting is only the first step. Proper post-harvest handling ensures quality and prolongs shelf life.
1. Husking
The green outer hull needs to be removed. If the walnuts are ripe, the hulls should come off easily. This can be done by hand (wear gloves to avoid staining from the juglone in the hulls), by walking on them with sturdy shoes, or using specialized hulling machines for larger quantities.
2. Washing
After husking, wash the nuts thoroughly to remove any clinging hull particles or dirt. Use a hose or a bucket of water, scrubbing gently with a stiff brush if necessary.
3. Drying
This is a critical step to prevent mold and ensure good storage.
- Spread Them Out: Lay the walnuts in a single layer on screens, elevated racks, or shallow trays in a well-ventilated area. Avoid direct sunlight, which can cause the shells to crack and the kernels to become rancid.
- Good Airflow: Ensure excellent air circulation around the nuts. A fan can aid in this process.
- Drying Time: Depending on humidity and temperature, drying can take anywhere from 2 weeks to a month. The nuts are dry when the kernel snaps cleanly when broken in half and the membrane between the kernel halves is brittle.
4. Curing (Optional)
Some growers allow walnuts to "cure" for a few weeks after drying by storing them in mesh bags or shallow bins in a cool, dark, dry place. This allows the moisture content to equalize throughout the nut.
Tips for a Successful Harvest
- Wear Gloves: The hulls contain a dye called juglone that can stain skin and clothes.
- Monitor Weather: Try to harvest during dry weather to avoid wet hulls and ground, which can lead to mold.
- Check for Pests: Inspect nuts for signs of insect damage before storage.
- Safety First: When using poles, be mindful of overhead power lines and slippery ground.
Walnut Harvest Summary
| Aspect | Details |
|---|---|
| Ripeness Cues | Hull splitting open, nuts falling naturally, testing high-up walnuts. |
| Primary Method | Shaking the tree (by hand or pole) to dislodge nuts. |
| Collection | Collect nuts immediately from the ground after shaking to prevent damage and maintain quality. Using tarps simplifies this. |
| Post-Harvest | Remove hulls, wash thoroughly, and dry completely in a well-ventilated area (2-4 weeks) before storage. |
| Storage | Store in a cool, dry place. For longer preservation, shelled walnuts can be frozen. |
For more detailed guidance on walnut cultivation and harvesting, consider consulting resources from agricultural extension offices like those at University of California Agriculture and Natural Resources.
