What are Winter Harvest Teas?
Teas in China and Taiwan may be harvested any time from once to six or seven times a year, depending on a number of factors such as climate, production requirements, cultivar and cultivation techniques.
For most areas the most important harvest in terms of value and volume is spring harvest- representing teas picked from February to May- a topic you can refer to on this guest post I wrote for World of Tea. Autumn harvest is generally considered the next most important and for certain types of teas on equal footing with spring teas.
Summer harvest though is typically only suited for producing black teas because the natural heat during that period aids the oxidation process and the value that black tea fetches is lower anyway. For example, in Huangshan, the spring harvest is used for making green tea while summer harvest is used for production of black tea, much of which goes into tea bags and RTD bottled tea.
Notable by its omission is winter harvest. In fact, in the rather comprehensive- not that any publication can be truly comprehensive for a topic such as tea- Cha Xue Gai Lun (Zhou Ju Gen et al published by Zhong Guo Zhong Yi Yao Chu Ban Se in 2007) mentions the various characteristics of spring, summer, autumn but not winter tea. This is how uncommon winter harvest is.
Generally, winter harvest tea are harvested around Li Dong (7th of November) on the Chinese agricultural calendar until mid to end of November.
In most parts of China, harvesting ceases by Oct of each year. In the southern regions though, notably Taiwan, winter harvest teas have been gaining quite a bit of popularity.
What’s with the winter harvest teas?
Typically tea plants hibernate from November each year to February and March each year. During this period, though the plants do not grow and bud, they continue to absorb nutrients. Tea plants only start growing when the ambient temperature is above 10°C. Plants would then bloom after a certain cumulative active temperature is reached.
Why spring harvest is the most valued is that the plants absorb the most nutrients before blooming since they enjoy the period of hibernation as well. By the same token, the summer heat means that the plants would quickly bloom before they had absorbed much nutrient. The cooler weather of autumn would put the tea plant in a better state compared to summer harvest.
These nutrients factor into the taste and health contributing compounds in the tea. That is why teas like Silver Needles which are traditionally most valued for their health contributing properties are only produced during spring.
The optimal point of sufficient heat to grow but not too much that the plant would bloom before absorbing enough nutrients is part of the reason why higher elevations are favored- all else being equal- for growing tea. The lower temperature and clouds that partially shields sunlight retard the blooming process, allowing plants to be better ‘developed’. The same logic applies for shading tea plants in the production of Gyokuro, one of the highest grades of Sencha.
Back to winter harvest.
In most parts of China, especially the northern areas, by October, temperatures would have fallen below 10°C, that’s why you will never hear of winter harvest from a northern area like Shandong for example. Not to mention the common winter droughts that plagues the north.
Where there is sufficient heat and rainfall during the period denoted as winter- notably Taiwan- plants can grow at a slower pace, forming more of the taste contributing compounds. Hence winter harvest teas are generally the sweetest of all and lower in bitterness and astringency.