True matcha is not just any green tea ground into powder. It comes from tea plants shaded for weeks before harvest, which pushes them to produce more chlorophyll, keeps the savory amino acid theanine from turning into bitter catechins, and creates its seaweed-like aroma. This episode explains the plant science and why much of the green powder sold worldwide does not meet the standard.

We trace the tea from salty, boiled tea-brick soups of the Tang dynasty to whisked tea in Song dynasty temples, the Ming emperor’s 1391 ban on compressed tea, and seeds brought to Japan by the monk Eisai. The story continues through Uji’s frost covers, samurai-era monopolies, and today’s supply crisis, including tariffs and new production in China.

• What ISO 20715 and Japanese labeling rules require for a product to be called matcha
• Why the Song dynasty elite prized white tea made from tiny tea buds
• How frost protection in Uji accidentally led to the shade-growing method
• The Edo-period tea jar procession and the difference between koicha and usucha
• Why slow stone milling, aging farmers, a 20% drop in the 2025 harvest, and a 15% U.S. tariff are squeezing supply