The Art of Pu Erh Tea Processing

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Pu erh tea is celebrated for its complex and diverse range of flavors, which stem from its distinctive processing methods, allowing the tea to age through microbial fermentation.
This blog post discusses the various stages of pu erh tea production, from initial harvesting to compression tea cakes, while providing insights into how each step shapes the complex aroma of pu erh tea. We also explore how these processes differ between raw (sheng) and ripe (shou) pu erh, offering valuable insights even for advanced pu erh tea lovers.
Note: For a detailed introduction to pu erh tea and the difference between raw and ripe pu erh tea, you may read this article: What is pu erh tea?
1. Harvesting
Picking tea leaves marks the first step in the processing of pu erh tea. Tea trees sprout fresh growth when they receive ample moisture followed by sufficient sunshine. In Yunnan, the best conditions for tea harvesting occur in spring (March-May) and, to a lesser extent, in autumn (September-October).
Some producers continue harvesting during the rainy summer months, but tea made during this monsoonal season, known as ‘rainy tea’ (yushui cha), is typically of lower quality. Moreover, harvesting tea during the summer months can impact the quality of tea produced in spring and autumn, as the tea trees become exhausted. Thus, when sourcing pu erh tea for our own tea cakes, we always avoid tea gardens that are active during the summer season.

When fresh leaves are ready, they are carefully plucked while still tender. The picking standard for pu erh tea is the first three to five leaves, including the bud. As every leaf is hand-picked, it's a highly labor- and time-intensive process. Harvesting tea from older, larger trees is particularly challenging, as it requires tea pickers to climb up the tree to gather the leaves. Beyond the precise picking itself, workers often face challenging hikes to and from remote growing areas.
2. Withering
As leaves are gathered into a basket during picking, they can bruise each other and start to oxidise. The oxidation process raises the temperature within the basket, creating a vicious cycle. To prevent this, it's essential to bring the fresh tea leaves to a processing facility as soon as possible. They're then carefully spread on bamboo mats or mesh-bottomed trays. This allows them to cool, slowly wilt, and lose excess moisture in a controlled manner, preparing them for the next stages of processing.
3. Pan-Frying (Kill-Green)
After withering, a process known as 'kill-green' (shaqing) begins. In this stage, the wilted leaves are carefully roasted by hand in an iron wok, traditionally heated over firewood. Once the wok reaches the right temperature, a fresh batch of leaves is tossed and turned, allowing water content to further evaporate.

The heat of the wok plays a crucial role, as it "kills" most, but purposefully not all of the enzymes responsible for oxidation. For raw pu erh, a small amount of these enzymes is intentionally left intact, laying the foundation for something truly magical.
Over time, through proper storage, these remaining enzymes work alongside bacteria and fungi to ‘age’ the tea in a process known as microbial ripening, transforming its aroma and flavor.

This method of stir-roasting is an art form in itself and requires the tea master to maintain a delicate balance: over-frying the leaves strips them of their distinctive raw pu erh character, turning them essentially into green tea. Under-frying, on the other hand, leaves the tea underdeveloped, resulting in a sour and lackluster brew. So far, machines have not become advanced enough to replicate the precision of hand-frying.
4. Rolling/Shaping
Once the stir-roasted leaves have cooled, they enter the next critical stage of tea production: rolling. At this point, the leaves remain tough and fibrous, unable to release their full potential when infused in hot water. Rolling transforms them, breaking down their cellular structure to unlock the rich flavors. This is where craftsmanship meets science, as the process requires just the right balance of precision and force.

Rolling can be performed by hand or with the help of machines. While hand-rolling is steeped in tradition, the use of machines often excels in delivering the consistency required for high-quality tea. Imagine the amount of steady, intense pressure needed to soften large quantities of leaves effectively, it’s a task almost impossible to achieve by hand alone. This is why most tea makers today rely on machines to ensure every batch is rolled to perfection.
However, machines still need to be operated with the supervision of humans. Under-rolling results in tea with a weak, underdeveloped character, while over-rolling creates an initial burst of intense flavor that quickly fades in subsequent steeps. When done properly, rolling produces leaves that release their fragrance effortlessly during brewing and offer a beautifully layered, evolving flavor profile through multiple infusions.
5. Sun-Drying
Sun-drying is the last step in producing 'rough' pu erh tea, also known as 'mao cha', which has yet to be compressed into tea cakes. This processing step is what gives pu erh its remarkable ability to age and transform over time. This traditional process depends on favorable weather, ample space, and significant manual effort.
Sun-dried tea leaves retain small amounts of enzymes and moisture, which are vital to shaping the unique characteristics of raw pu erh tea: its aroma, flavor, and ability to mature and develop complexity when stored under the right conditions. In contrast, machine-drying often over-dries the tea leaves, destroying critical enzymes and resulting in a green tea like taste.

For us, sun-drying is non-negotiable when it comes to crafting high quality pu erh teas. It’s a challenging process, but one that ensures the tea retains its authenticity and potential for aging beautifully.
At this stage, the tea has completed its rough processing and is now referred to as "maocha." While maocha can be enjoyed as a fresh tea, it is most often subjected to further processing. The maocha is either compressed into raw pu erh cakes, or it undergoes a wet-piling fermentation process to create ripe pu erh.
6. Wet-Piling (Fermentation)
For ripe pu erh tea, the leaves undergo a unique fermentation process called wo dui, or wet-piling. The dried leaves are piled into heaps, sprinkled with water, and covered to create a warm, humid environment. This encourages microbial activity, which transforms the leaves over several weeks. The fermentation process darkens the leaves, mellows their flavor, and imparts the deep, rich taste that ripe pu erh is known for. Raw pu erh, on the other hand, skips this step and ages naturally over time.

The process of fermenting ripe pu erh tea involves several key steps:
- Moistening: Water is sprayed on tea piles (30-50% of the tea’s weight) to ensure even fermentation, with water amounts adjusted based on leaf quality.
- Piling: Tea is stacked in windrows 50-70 cm high, depending on leaf coarseness.
- Covering: Piles are covered and kept at 50-65°C, releasing excess moisture and dropping in height over time.
- Turning: As the temperature inside the pile of tea is warmer compared to the outer layer, the pile of tea needs to be turned every 2 weeks to ensure the tea is fermented uniformly and to prevent pile-burning that spoils tea. While turning, any clumps in the tea are broken apart to further support optimal fermentation.
- Furrowing: Piles are furrowed daily toward the end of fermentation to reduce temperatures and water content to 14%, ensuring full fermentation without overheating.
- Airing: Tea is spread out after roughly 45 days to cool and stabilize at normal water content. The exact amount of days will depend on whether the tea master wants to achieve a lighter or stronger fermentation.
- Quality control: Any impurities like stones and stalks are removed.
7. Steaming & Compression
During this step, the tea is carefully weighed in a metal cylinder, often with a carefully placed inner paper ticket (nei fei) tucked beneath the top layer of leaves. The cylinder is then placed over a jet of hot steam. The softened tea is then transferred into a cloth bag, wrapped tightly into a compact ball, and secured with a firm knot. The tightly bound bundle is placed under a large stone and pressed manually, shaping the tea into the classic tea cakes. In more affordable production methods, hydraulic presses are often used instead of manual stone pressing, ensuring efficiency while still creating the familiar shape.
Once pressed, the newly formed tea cakes are placed on racks to rest and dry. As the cakes cool, the cloth wrapping is removed, and the tea is left to fully dry, completing its transformation.
Beyond the well-loved tea cake shape, pu erh tea is also compressed into other shapes, such as bricks and bowl-like tuocha. Unlike tea cakes, these shapes are always formed through hydraulic compression, ensuring sufficient tightness and consistency.
8. Sorting & Packing
Once the tea cakes have dried sufficiently, they're wrapped in paper. The process begins by stamping the wrappers with the tea's production date. The cakes are then placed front-side down in the middle of the paper, and the paper is carefully pinched and pulled toward the center. Finally, the last corner is tucked in to create a secure, tidy package.
In some cases, a thin layer of tissue paper is added as an inner lining to provide extra protection and extend the tea’s longevity. In fact, all Teasenz brand pu erh tea cakes enjoy this extra layer of protection.
Modern tea wrappers often feature beautiful designs, unique artwork, and branding alongside essential information such as the tea’s type, production year, and origin.
At last, the tea cakes are wrapped in bamboo 'tongs' and either labelled or lasered to make sure one knows what's inside:
9. Aging
Unlike most teas, pu erh tea improves with age, developing deeper and more nuanced flavors over time. As raw pu erh isn't pile fermented there's more aging potential compared to ripe pu erh tea.
During aging, the tea undergoes slow oxidation and microbial fermentation, which enhance its complexity and smoothness. The storage conditions, including humidity, temperature, and airflow, play a vital role in shaping the tea’s aging process.
While still niche in the West, pu erh is steadily gaining traction and hopefully one day could finally break into the mainstream. For more information about pu erh tea, you may visit our pu erh tea 101 page for more details.