To make black tea, the fresh leaf is withered by exposure to air and is broken and left to ferment after picking. For green tea, the leaf is not fermented at all. It is steamed immediately after harvesting to stop the fermentation process. Sencha is dried after steaming and, when dry enough, rolled into a variety of shapes until it is completely dry. The quality of sencha is, however, highly variable.
Quality depends on the tea's origin, the season, and leaf processing techniques that are used.
For gyokuro only the youngest flush leaf is picked. Special cultivation techniques are employed to produce a tea that is famous for its rich flavor and pale lemon-green color. Gyokuro tea plants are grown in the shade for approximately three weeks before harvesting begins. Removing direct sunlight in this way reduces leaf photosynthesis which alters the proportions of flavenols, amino acids, sugars, and other substances that provide tea aroma and taste. This aging blends and mellows the flavenoids and other organic compounds to produce a tea that is renowned for its smooth elegant taste.