Nowhere in the growing or processing of hemp is good judgment more needed than in determining the time to end the ret. Experience and good judgment are necessary to determine just when the hemp stalks should be lifted from the field and bundled. The lifting and shocking stops the retting action. The value of the fiber can be cut in half or entirely lost by several days' overretting in warm weather.
In Kentucky, hemp spread immediately to ret after harvest is apt to sunburn, or sunscald. It is common belief that the hot, bright days in August and September in some way cause deterioration of the fiber if spread for retting. Sunburned fiber is uneven in color, usually has less strength, and possibly is drier and more harsh than fiber not sunburned. In order to avoid sunscalding, the hemp is shocked after being harvested and not spread for retting until the cooler days of November. In locations having climatic conditions similar to those prevailing in Wisconsin, sunscald of hemp is rare.
In dew retting the spread stalks should be turned once or more during the retting period. This aids in bleaching the stalks and results in fiber of more uniform color and quality. The turning is done by workmen using bent poles approximately 8 to 10 feet in length. The poles are pushed under the head ends of stalks in the swath, and the stalks are turned over without moving the butt ends.
In turning the straw the workmen start in the middle of the field, turning the first swath into vacant center space. The second swath will be turned to lie where the first swath had been, and so on.
Care should be exercised in turning to prevent the stalks from tangling. The more hemp is handled, the more tangled the stalks may become. Tangled hemp is more difficult to process and produces a high proportion of tangled, short, tow fiber.