Spring Taiwanese oolongs begin to arrive in the market in early April, but the last of the Taiwanese oolongs arrive only in late May/early June. Why do some oolongs arrive relatively early while others arrive at the beginning of summer? Why is the oolong season so long in Taiwan? The answer is elevation.
Lower elevation teas, such as those grown at around 500m, will be harvested beginning in March. As the weeks progress, harvesting continues at ever higher elevations, ending in May with the harvesting of the highest elevation teas.
Spring Harvest by Elevation:
Chilly Nights and a Short Growing Season
The reason for harvesting first at lower elevations and moving upwards later in the season has to do with the influence of elevation on the growing cycle of the tea. The growing season arrives later and ends earlier at higher elevations. At the same time, these higher elevation tea bushes grow more slowly than those planted at lower elevations. Tea grown in Lishan, HeHuanShan, YuanFeng, DaYuLing, etc. all grow more slowly and during a shorter growing season than lower elevation tea bushes.
The best temperature range for these bushes to grow is between 18-25°C. The tea will stop growing when the temperature dips below 15°C. Because of the wide range between daytime and nighttime temperatures experienced at these higher altitudes, the leaves stop growing during cold nights, only resuming to grow when the temperature climbs back up. Growth is much slower as a result.
For the Winter Teas (that are harvested in the fall at the end of the growing season), the order of harvesting is reversed with higher elevation teas being picked first before temperatures become too cold.