Walnuts offer a rewarding harvest. The two most common types are the thin-shelled English walnut (Juglans regia) and the hard-shelled Black walnut (Juglans nigra). Although hulling differs slightly based on shell thickness, the general steps for collecting and curing remain consistent. This guide covers the practical stages required to successfully harvest these nuts.
Identifying Readiness and Timing
The process begins by recognizing the precise moment the walnuts are ready to be gathered, which typically occurs from late summer into early fall. A primary indication of maturity is the change in the outer hull’s appearance. Initially firm and green, the hull will begin to soften and transition to a yellowish-green or brown hue as the nut inside fully develops.
This color shift signals that the connection between the hull and the inner shell is weakening. The most reliable sign of readiness is the natural dropping of the nuts from the tree to the ground. Ready walnuts detach easily, often after a light shake. Waiting until the nuts have fallen ensures they have reached peak ripeness.
Gathering the Nuts
Once the nuts have begun to fall, collecting them quickly prevents mold development or pest damage. The outer hull contains juglone, a natural pigment that leaves dark brown or black stains that are extremely difficult to wash off. Therefore, wearing thick, impermeable gloves, such as heavy-duty rubber or nitrile, is necessary to shield the hands during handling.
The nuts can be gathered using simple tools like a rake and a bucket, but mechanical aids, such as specialized nut rollers or sweepers, pick up fallen nuts efficiently. When moving around the harvest area, be mindful of fallen walnuts, as stepping on them can crush the hull and release juglone onto the ground and footwear. Move the collected nuts immediately to the hulling area.
Hulling and Initial Cleaning
Removing the outer, fleshy husk is the messiest but most important step in preparing the walnuts for curing. The hull must be removed because it retains moisture, which encourages the rapid growth of mold, and the juglone residue can negatively affect the flavor of the nutmeat. For smaller batches, one can use a simple method like placing the nuts on a hard surface and stomping on them while wearing old shoes to crack and detach the soft hull.
Larger harvests often benefit from mechanical assistance, such as using a dedicated hand-cranked or electric huller designed for this purpose. Alternatively, some growers carefully drive a vehicle tire over a thin, contained layer of nuts to crush the hulls without cracking the hard inner shell. Regardless of the method used, the goal is to separate the tough outer material from the clean, intact inner shell.
Immediately following hull removal, the nuts must be thoroughly washed to remove fibrous debris and sticky juglone residue. This is accomplished by spraying the nuts with a strong jet of water, such as a garden hose with a sprayer nozzle or a low-pressure power washer. Agitate the nuts during the rinse to ensure the entire surface of the hard shell is clean. Discard any nuts that float, as they are likely infertile or damaged.
Curing and Long-Term Storage
After the nuts have been hulled and washed, they require a period of curing, which is a slow drying process. Curing reduces the moisture content within the nutmeat, preventing rancidity and inhibiting mold development. Spread the nuts in a single layer on screens or trays to maximize air circulation around each shell.
The ideal curing location is a cool, dry area that is well-ventilated, such as a screened porch, a dry basement, or a garage. Direct sunlight or high heat should be avoided, as rapid drying can compromise the quality of the nutmeat. The curing period typically lasts for two to four weeks, depending on the ambient humidity and the size of the walnuts. The nuts are considered fully cured when the shell is completely dry and the nutmeat inside is crisp rather than rubbery.
Once fully cured, walnuts can be stored in the shell for long periods in a cool, dark location, such as a root cellar or pantry. For the longest preservation, the nutmeats can be shelled and then placed into airtight containers. These shelled nutmeats can then be kept in a refrigerator for up to a year or frozen for several years without significant loss of quality or flavor.