Walnuts grow on trees. Most walnuts grown commercially are English walnuts. The most common varieties of English walnuts are Vina, Hartley, Serr, Tulare, Howard, and Chandler. When walnuts are in the growing stage they are surrounded by a green husk/hull. The actual thickness of the shell of the walnut within the hull varies depending on the variety. Walnuts are typically harvested September-October every year. Walnut harvest typically coincides with the hulls falling off the walnuts and walnuts falling to the ground.
Not all nuts mature at the same time so when the majority of the crop is ready the grower will mechanically shaker trees with a shaker. The shakers are mounted with rubber pillows. These rubber pillows clamp the trunk of the tree of limb and shaker the tree until the majority of the walnuts have fallen from the tree. This shaker moves from tree to tree throughout the orchard shaking all the walnuts to the orchard floor.
The harvester then goes through the field picking up the walnuts in the wind rows made by the sweeper. The harvester mechanically removes trash, leaves, and sticks from the wind row prior to dumping the walnuts into a cart that is pulled behind the harvester. A Runner works with the harvester unloading the walnuts from the harvesters cart into their own cart. The Runner is designed so the Harvester does not have to stop. The Runner unloads walnuts from the harvester and brings them to an elevator to load into sets of doubles that are delivered to a huller.
The huller is designed to remove any trash, sticks, and hulls from the incoming walnuts and dry the nuts to a moisture level of 8% or less. Since walnuts mature at different times some walnuts still have the green hull on them. The Huller removes these hulls with stiff metal brushes that scrape the outside of the walnuts. Walnuts are electronically and hand sorted to remove any sticks or defect walnuts. Walnuts then are dropped onto conveyor belts and placed into large dyer bins where air is applied to reduce the moisture level to below 8%.
Once walnuts are needed for processing they are placed into a fumigation chamber where they undergo treatment to rid the walnuts from pests using an approved fumigant. Once walnuts have undergone to appropriate exposure time and off gassing requirements the bins are unloaded and ready to be processed.