During the annual growth and development cycle of tea plants, it is affected by seasonal climates such as temperature, rainfall, and sunshine, as well as the differences in the nutritional conditions of tea plants themselves, so that the quality of tea in each season is also different. "Spring tea is bitter, summer tea is astringent, it should be delicious, autumn white dew (referring to autumn tea)", this is a summary of the natural quality of tea leaves in each season. According to the twenty-four solar terms of the lunar calendar, the tea produced from the date of mining in the spring tea garden to the time of the small full is generally called spring tea; the tea produced from the small man to the beginning of the autumn is summer tea; the tea produced from the beginning of the autumn to the closure of the garden is autumn tea. There are also winter teas in a few southern tea areas (November to December). Due to the different ecological environment, sunshine, temperature, precipitation, humidity and nutrient conditions of tea garden fertilization in different seasons, the reproductive characteristics, physical traits and chemical composition of tea tree shoots are different, and the quality of tea is of course different. In the case of green tea, due to the moderate temperature in spring, weak light intensity, abundant rainfall, and the tea plant recuperation through the long autumn and winter of the previous year, the spring buds are fat, tender, tender, emerald green, soft leaves, rich luster, young buds have more hair, the fewest purple buds, and the natural quality of fresh leaves is better. Due to the low temperature, weak light and rain in spring, under this ecological condition, it is conducive to the metabolism of nitrogen in the tea plant (the formation of proteins, amino acids), while the metabolism of carbon (the formation of tea polyphenols and sugars) is relatively slow. Chemical components related to the formation of green tea quality, such as proteins, amino acids and other nitrogen-containing compounds, are synthesized more, while the polyphenol content of tea is relatively low, and the formation of hexenol, pentenol and 2-hexenol with fragrance-type aroma components is also more. Therefore, spring tea has a fresh taste and strong aroma, especially early spring tea is often the best time of year for green tea quality. Many famous teas, such as high-grade West Lake Longjing tea, Biluochun, Huangshan Maofeng, Liu'an Gua Tablets, Taiping Monkey Kui, Guzhu Purple Shoots, Kaihua Longding, etc., are made of fine processing of the young buds and leaves of early spring tea.
High summer temperature, high sunshine intensity, is conducive to tea plant carbon substitution t, the formation and conversion of sugar compounds is more, tea polyphenol content is high, amino acid decomposition speed is fast, the content is significantly reduced, the content of anthocyanins and caffeine with bitter taste is increased, and the content of pentenol and hexenol with a clear fragrance is low. The buds are thin and small, the leaves are thin, the purple buds are many, and the green tea shape is light and fluttering with it, the aroma is not strong, the taste is bitter, it is not fresh, the bottom of the leaf is blue, and the quality is poor.
The climatic conditions for the growth of autumn tea are between spring and summer. The temperature in late autumn is low, mostly around 28 °C, which is conducive to the formation of floral aromatic substances (such as phenethyl ethanol, phenylacetaldehyde), and the tea leaves often have a floral fragrance, which is very beneficial to the production of oolong tea. However, due to the low air humidity, the nutritional conditions of the tea plant itself are not good, the buds are thin, the leaves are thin, the size is different, the leaf bottom is brittle, the leaf color is yellow, and there are more purple buds. Using this raw material to make green tea, there are often drawbacks such as green soup color, dark blue bottom flower, aroma, and bland taste.
Of course, as far as the quality of black tea is concerned, due to the high summer temperature, the tea polyphenol content in the tea leaves is higher, which is beneficial to the formation of more black tea pigments. Therefore, the black tea made of summer tea, dry tea and tea soup is more ruddy in color and the taste is more intense; but the amino acid content in summer tea is significantly reduced, which is also unfavorable for the fresh taste of black tea.