Steep green tea for 2 minutes 30 seconds at 80°C (176°F).
Green tea is Camellia sinensis leaf heated soon after picking — steamed in Japan, pan-fired in China — to stop oxidation before it starts. That halt is the whole point. It keeps the chlorophyll and the fresh, vegetal character that a black tea trades away for malt. Japanese greens like sencha and gyokuro lean marine and savory; Chinese greens like dragon well are nuttier and rounder in the mouth. Green tea also keeps poorly compared with darker leaf, so buy it in small amounts, store it away from light and heat, and drink it within a year of harvest.
Take the kettle off the boil and let it stand a few minutes, or add a splash of cold water — 80°C (176°F) is well below boiling, and a variable-temperature kettle or a cheap thermometer removes the guesswork entirely. Use about a teaspoon of leaf per 250ml cup and give it room; a cramped ball infuser stops the leaf opening. Pour down the side of the vessel rather than straight onto the leaves. 2 minutes 30 seconds at medium is the starting point, 1 minute 55 seconds for something lighter, 3 minutes 15 seconds if you want more body. Taste at the end rather than trusting the clock alone.
Boiling water. It ruins more green tea than everything else combined, and it happens by default, because most kettles have one button. Water straight off the boil scalds the leaf, and what reaches the cup is a flat bitterness with none of the sweetness underneath it. The second mistake is walking away. Green tea moves fast, and the gap between 2 minutes 30 seconds and five minutes is the gap between a bright cup and an astringent one. Lift the leaf out the moment the timer sounds instead of letting it sit in the water while you drink.
Green tea takes a second steep well, and a good loose leaf takes a third. Pour the first cup off completely — leaf left standing in hot water keeps extracting, so the next infusion starts already tired. Add roughly thirty seconds to each successive steep to make up for what the one before it took. The second cup is usually softer and sweeter, with the grassy edge sanded off; the third is thin but pleasant. Bagged green tea is the exception. The leaf in it is already broken small and gives everything it has in one go.
Steep green tea for 2 minutes 30 seconds in water at 80°C (176°F) — 1 minute 55 seconds for a lighter cup, 3 minutes 15 seconds for a stronger one. The longer it stands the more of the bitter catechins it gives up, so green tea is one to lift out when the timer sounds rather than leave sitting in the water.
Almost always because the water was too hot or the steep too long. Use 80°C (176°F) rather than boiling water, and 2 minutes 30 seconds rather than five — bitterness in green tea comes from catechins the leaf releases when it is scalded or left standing.
Use one level teaspoon of loose leaf, or one bag, per 250ml cup. Japanese greens like sencha are often measured a little heavier and steeped a little shorter, which gives a fuller cup without more astringency.
Roughly 20 to 45mg per 250ml cup, about a third to a half of a coffee. A shorter, cooler steep at 80°C (176°F) extracts less of it, so a light green tea sits at the bottom of that range.