After a walnut sapling is planted, it takes ﬁve to seven years
for it to grow into an adult tree suitable for harvesting. Although many
varieties of walnuts are grown in California, four account for over 80% of
total production: Chandler, Howard, Hartley, and Tulare. California walnuts
are protected from contamination because of the nut’s double envelope of
hull and shell while on the tree.
Harvesting begins in late August to mid-September when the green hulls
start to split which signals the beginning of harvest. First the orchard
ﬂoor is swept clean. Mechanical shakers vigorously shake each tree and
thousands of walnuts fall to the ground. The walnuts are carefully swept
into windrows to allow mechanical harvesters to pick them up for cleaning.
The walnut harvest time period is short; typically all walnuts are harvested
within a six-week window.
Walnut Shells: Uses & Applications
Walnut (Juglans Regia) Shells are a versatile soft abrasive media. Walnut Shells are carefully crushed, ground and classified to standard mesh sizes, ranging from abrasive grits to fine powders. Walnut Shells have unique physical characteristics and chemical properties that make them suitable in a wide variety of industrial applications including: walnut shell blasting, cleaning, tumbling, polishing, fillers in manufacturing, non-skid flooring, and filtration; as well as uses in pet litters and cosmetics & soaps.
Physical Characteristics of Crushed Walnut Shells
Crushed walnut shell grit is high strength, long-lasting, all-natural and biodegradable. It has a hardness of 3.5 MOH and 91 Rockwell, and specific gravity of 1.2-1.4. Walnut shells resist fermentation and perform well in a wide range of temperature and pH conditions.