In California, walnuts are harvested from August until November. Walnut growers start harvesting walnuts when about 75% of hulls have split. In most countries, farmers harvest by hand, through shaking the branches so that walnuts can fall in special collection nets that have been put in the ground. However, in large commercial orchard of United States, big vibrator machines (shakers) attach to the mature walnut trunk and shake it violently, so that hundreds of walnuts fall in the ground. Then, a special machine picks the walnuts from the ground and makes a necessary first stage sorting (broken stems and leaves are removed). In most cases, the nuts are then put in special machines, where the hulls are carefully removed and the nuts can dry properly. From this point onwards, the processing differs on whether each market demands shelled or unshelled nuts.
The average walnut tree starts to produce nuts at an age of 8-10 years. However, there are cases in which walnut trees start to produce about 15-22 lbs. (7-10 kg) of nuts at an age of 5-7 years. Most commercial walnut orchards reach their peak production level at an age of 30 years or more. Healthy and mature walnut trees produce from 66 to 350 lbs. (30 to 160 kg) of nuts, but this production cannot be achieved every year. The tree has an inherent tendency towards alternate bearing, and it usually yields a good production in every other year.
When it comes to realizing profit from selling English and black walnut trees as wood, there are not many rules of thumb or average prices. Every tree is different and can be marketed in a different way. Of course the prices vary significantly between countries. In general, the tree diameter is measured at a height of 4,5 feet (1,37 meters) from the ground, and this figure is important. A good healthy tree with dense high quality timber should be normally left to grow more than 20 inches (51 cm) in diameter. On the contrary, the less vigorous trees that are close to a dominant tree can be thinned and sold when they reach a diameter of 12-14 inches (30-35 cm).
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