Oolong teas is often considered one of the most universally appealing tea varieties because they share some characteristics with both green and black teas.
Among all tea types, Oolongs are also the most complex—shaped not only by their growing conditions but by an intricate sequence of processing stages. Below, you’ll find a step‑by‑step look at how Oolong tea is made and how its controlled oxidation is the key to Oolong depth and complexity.
The steps in producing Oolong Tea
The basic processing steps of olong are: plucking, sun‑withering, indoor‑withering, oxidation, fixing, rolling, shaping, baking or roasting, and drying.
Oolong’s many processing steps give producers fine control over the finished tea’s flavour, appearance, aroma, and overall mouthfeel.
Cultivation
The rugged, mineral‑rich landscapes where oolong tea is grown greatly influence its character. High‑mountain plantations with rocky soils encourage deep root growth, allowing the plants to absorb a diverse range of minerals. This contributes to oolong’s layered aroma and long‑lasting flavor. Famous cultivars like China’s Tie Guan Yin and Taiwan’s Dong Ding owe much of their complexity to this unique combination of altitude, rocky terrain, and careful cultivation.
Plucking
The process begins with hand‑plucking the tea buds once they reach the desired stage of maturity, which typically involves harvesting not the bud itself but the first and second leaves, with the two subsequent leaves. Because many oolong cultivars are grown on steep, mountainous terrain, harvesting is usually done manually.
These more mature leaves contain higher concentrations of amino acids and carotenoids compounds that significantly contribute to the floral, sweet, and creamy notes often found in oolong teas. Their maturity also makes them more robust, allowing them to withstand the multiple stages of oolong processing.
Sun Withering
After plucking, the leaves undergo an extended withering stage to develop their full aromatic potential.
During solar withering, direct sunlight induces slight sunburn on the leaf surface, stimulates the formation of aroma compounds by increasing oxidation beyond what would occur indoors. The leaves are carefully spread on bamboo or mesh trays for several hours, and periodically shaken to redistribute moisture, create slight micro‑damage on the surface, and ensure that the water content is released gradually and evenly.
Indoor Withering
After sun exposure, the leaves are brought indoors, where airflow, humidity, and temperature are carefully controlled. Indoor withering enhances body and depth, creating a smoother texture, increased sweetness, and a richer aroma.
The combination of outdoor and indoor withering produces the wide spectrum of diversity found in oolong teas.
Oxidation
The next step, oxidation, is one of the most delicate stages in tea processing, as it strongly shapes the tea’s final character. The leaves are spread out on bamboo trays and gently stirred at regular intervals. This light agitation causes the leaves to rub against the bamboo surface, softening their cell walls and releasing aromatic oils.
This stage typically lasts 10 to 18 hours, depending on the desired style of tea and environmental conditions.
As a result, Oolong teas generally fall into three main categories.: lightly oxidised varieties like our Formosa Dong Ding Wulong; medium oxidised teas such as our Formosa Tie Guan Yin Premium ; and heavily oxidised Oolongs like our Jeju Island Dark Oolong. The least‑oxidized Oolong teas share similarities with green tea but generally show less bitterness. With higher oxidation, the fresh green and cut‑grass aromas diminish, giving way to richer, more floral ones.
Fixing, rolling and shaping
This process is designed to stop oxidation by rapidly applying high heat, which denatures the enzymes responsible for it, without fully drying out the leaf.
After fixing, the leaves are wrapped into a cloth ball and allowed to cool for a few minutes to help retain their moisture. They are then placed into rolling machines, where they are vigorously rolled. This motion causes the leaves to rub against the machine’s surface to release their aromas.
Subsequently, the cloth balls undergo a second roasting at moderate temperatures. This step stabilises the aromas and reduces excess moisture.
These cycles of roasting and cloth‑ball rolling can be repeated several times. This process shapes the leaves into rounded balls.
While ball‑rolling is the most common method, oolong can also be rolled manually into long, curved leaves—the most traditional style.
Baking/roasting and drying
At this stage, most oolong teas are baked in ovens or over charcoal for many hours at low temperatures to further develop their flavour and texture, refine the aroma, and remove most of the remaining moisture.
After this phase, the leaves are dried at a moderate heat to remove any remaining moisture.
Finally, the stems are removed, the leaves are sorted for quality, and packed.
Conclusion
Oolong teas develop their unique character through a combination of mineral‑rich mountain terroir and a complex, multi‑step production process. The most important stage is the controlled oxidation, which defines each tea’s flavour and aroma.
