The main producing areas of Job's tears are distributed in warm, humid regions such as Guizhou, Yunnan and Fujian.

Job's tears is the seed kernel of the grass family plant Job's tears (Coix lacryma-jobi), also known as coix seed or yi mi. The plant prefers a warm, humid climate and is mostly grown in low-altitude river valleys and on slopes. In China, the main producing areas of Job's tears are concentrated in Guizhou, Yunnan, Guangxi, Fujian, Hunan and other provinces and regions; among them, Guizhou stands out for both the scale of its coix cultivation and its reputation, and places such as Xingren have long been known as the hometown of coix.

Job's tears from different producing areas differ slightly in grain size and taste. Guizhou coix grains are plump and of stable quality; Pucheng Job's tears in Fujian has a long cultivation history and is a well-known local specialty agricultural product; the Job's tears of Yunnan and Guangxi are mostly grown in mountainous and hilly areas, where abundant rain favors grain filling and ripening. There is also scattered cultivation in Taiwan, China, mostly concentrated in the central region, while some of the coix on the market comes from imports from Southeast Asia.

In terms of growing conditions, Job's tears is highly adaptable, likes light and moisture, and is suitable for soil with a deep layer that retains water and nutrients, but it is not tolerant of drought or frost. It is generally sown in spring, and during the growing period the soil should be kept sufficiently moist, with attention paid to controlling diseases such as smut; once the fruit husk turns brown and the grains are hard, it can be harvested and dried.

When selecting, those with whole grains, a clean white color, and a dry texture without off odors are best; do not buy any with a musty smell or that have clumped from moisture. Job's tears can be used to make porridge or soup, and can also be ground into flour for baked goods. Traditional Chinese medicine considers it to have the effects of promoting diuresis and draining dampness and of strengthening the spleen, and it is often eaten together with red beans. After buying it, store it sealed in a cool, dry place to avoid insect infestation and spoilage.