Growing & Processing

Find out how walnuts get from the tree to the store.

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From Harvest to Market

Each step in the process from propagation, to harvest, to packer, and finally to market is handled with care and attention. There are over 4.000 walnut growers, a large majority being family farms, many of which have been in the walnut business for several generations.


Walnut production takes commitment and patience, and orchards are dedicated solely to walnut production. After a walnut sampling is planted, it takes five to seven years for it to grow into an adult tree suitable for harvesting. A walnut tree can bear fruit for 100 years. Although many varieties of walnuts are grown in California, six account for more than 75 percent of total production: Hartley, Chandler, Serr, Vina, Franquette and Howard.


Harvesting begins in late August and continues through November. The walnuts are ready for harvest when the outer green hulls begin to dry and split, allowing the in-shell walnuts to be removed. Mechanical shakers vigorously shake each tree and thousands of walnuts fall to the ground. The walnuts are carefully swept into windrows (rows of walnuts raked into heaps) to allow mechanical harvesters to pick them up for cleaning.

Processing – Hulling

Once the walnuts are harvested, pre-cleaners are used to clean the walnuts so they are ready for hulling. A huller removes the outer green hull and the nut is mechanically dehydrated (air dried) to the optimum 8 % moisture level, preventing deterioration of the nut and protecting its quality during storage. Hulled walnuts are transported to nearby packing plants and are stored until needed for cracking.


Walnuts are transported to a packing plant where they are graded based on usage, in-shell or shelled. Shelled walnuts are further graded by color, as shown in the official walnut color chart. Walnut kernels are screened and separated into different sizes.

Find out more on Walnut Product Types

Handler List

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