Frankly speaking, there is no national mandatory standard.
That's why the words "High Mountain Green Tea" can be printed on any tea bag, and no one will check or care.
However, there is a conventional definition in the tea industry:
Tea grown at an altitude of over 600 meters can be called high mountain tea. Areas above 1000 meters are recognized as premium high mountain tea producing regions.
This standard was not arbitrarily set by any institution, but rather represents a consensus accumulated over decades by tea farmers, tea merchants, and tea science researchers. The underlying logic is as follows: beyond 600 meters, the impact of mountain climate on tea quality becomes significant; beyond 1000 meters, this impact becomes more stable and prominent.
What are the benefits of high altitudes for tea leaves?
Four words: slow, cool, foggy, difference.
Slow: Due to the high altitude and low temperature, tea leaves grow slowly. The slower the leaves grow, the more fully the internal substances are accumulated - this is why high mountain tea tastes rich and layered, rather than having the flavor dissipate in one sip.
Cool: The temperature is low, so there are fewer insects. It's not that we don't want to use pesticides, it's just that we don't need to. Our tea garden is located at about 1000 meters, and in June and July, we still need to wear jackets when going up the mountain. It's chilly in the morning, around 20 degrees Celsius. At this temperature, most tea tree pests can't survive for long. The grass in the garden is manually hoed, and the branches are manually pruned. There's no such thing as pesticides.
Fog: There is much cloud and fog in the mountains, and the air humidity is high. The tea trees are immersed in fog all day long. Fog scatters sunlight, transforming direct strong light into soft diffuse light, which makes photosynthesis of tea leaves more uniform, and both chlorophyll and amino acids are a little more abundant. This is one of the sources of the fragrance of high mountain tea. In our place, fog is most prevalent in spring, and there is often a rainy season as well. Sometimes, when people stand in the tea garden, with fog under their feet and around them, they can only see a few tea trees near their hands
Difference: There is a large temperature difference between day and night. During the day, photosynthesis synthesizes sugar and aroma substances. At night, when the temperature drops, these substances are consumed slowly and accumulate in the leaves. The greater the temperature difference, the higher the aroma of the tea, the sweeter the taste, and the longer the aftertaste. Tea gardens at low altitudes have a small temperature difference between day and night, resulting in less aroma accumulation. This is why the same variety of tea grown on flat land and high mountains tastes significantly different.
