This is the second half of an interview article with William Osmont of Farmerleaf, with more on Yunnan and pu’er related tea production. Read part one here.

What tea aspects indicate that a pu’er will age well, or what types of teas would it make more sense to not age?  One sometimes hears that in the original Chinese tea culture pu’er wasn’t intended to be aged to improve it; any thoughts on that?

Good Huigan (sweet and fresh feeling in the throat) will be sustained through the years, and this is one of the main criteria on which pu-erh tea is evaluated.

Make sure the tea you aged doesn’t taste like green tea or isn’t too red when young. This degree of greenness depends on the way the kill-green process was done. An overly green or red pu-erh tea can be very enjoyable when young, and be disappointing after years of aging.

The big tea factory blends are generally intended to be aged, [and] they are not suitable for immediate drinking. Blends can be a safe choice for long term aging, even though they rarely contain high-quality material.

Bitterness tones down with age, but it doesn’t mean bitter teas will necessarily give a better tea once aged. For example, Yiwu tea generally has no bitterness, but it’s a sought after terroir for long term storage; this kind of tea can be unimpressive when young and turn into great sweet and complex teas after a couple of years of aging.

The Pu-erh tea culture is constantly changing; in its most current form, it is considered this tea can be enjoyed young, as it was consumed in Yunnan, and aged, as it was consumed in Guangdong. The Tibetan way of drinking it with Yak butter doesn’t seem to have spread much. In a pre-industrial context of smallholders, it was technically much easier to produce Pu-erh tea than other types of teas. When made in small quantity, the only piece of equipment required is a wok. Sun-drying was used to dry tea, just like it was used to dry fruits, corn or cabbage.

The tea culture has been shaped through the constraints of production and logistics. People like wet-stored tea in Guangdong because that is the way tea would turn out in those conditions. Some tea lovers in the West build “pumidors”, while I have never found one in China. It is beautiful to see the tea culture evolve as tea spreads throughout the world.

What is the local (Yunnan) understanding of ideal and problematic pu’er storage conditions?  Is environment humidity the primary concern?

In Yunnan, few people actively control humidity; they typically store the tea cakes in their bamboo wraps in cardboard boxes. When stored in large quantity, the air flow is somewhat limited, which is believed to preserve the fragrance of tea. Some tea professionals limit the air exchange further by wrapping the boxes with plastic sheets.  This technique makes sense as long as the leaves are not vacuum sealed. The aging process does require oxygen to occur, but the air contained inside the box should be enough for decades. A minority advocates for a complete removal of oxygen, this slows down the oxidation process and the tea profile evolves in a very different way.

Aging is the result of enzyme activity, called “enzymatic browning” in the food industry, and the action of micro-organisms. The relative importance of each in the aging process depends on humidity. In wet environments, microorganisms take a large role in tea oxidation, while in dry environments, their action is negligible. This probably explains the difference in taste profile that we can observe between wet and dry-stored teas.

What is the difference between using tea from just one plant to make tea versus mixing it?  Per input related to other tea types (eg. Dan Cong) the range of characteristics would be narrower; is this the same?

Pu-erh tea Single tree productions have been popular for a couple of years. Since only one or a handful of trees are harvested, the result in the cup varies widely. Some can have a very good throat-feel; others can be bitter and astringent, or sweet and fragrant… A big part of the appeal is to have the picture of the big tree and the feeling of tasting something very old. Self-suggestion can go a long way to make your session enjoyable, even though such productions wouldn’t necessarily perform better than a standard “gushu” harvest in a blind tasting.

Such productions are valuable by their limited quantity; you can hardly get more than a kilogram of dry tea from a single ancient tree. They can feature traits that are unexpected in their area of production and tend to change less along the infusions than standard productions that involve thousands of trees.

How much tea (leaf weight and dry weight) can an individual tea tree produce?

It really depends on the size of the tree, frequency of harvest, varietal, nutrient availability, water, sunlight, pest and disease, pruning method… It can go anywhere between 500g and 5kg of fresh leaves per year (about 120g to 1.2kg of dry tea). Some trees are picked three times a year, while other are picked thirty times.

What is your impression of how tea tree age affects pu’er quality or characteristics?

The leaves harvested from ancient gardens tend to have a better Huigan (sweet and fresh feeling in the throat), they can feature more pronounced bitterness that turns quickly into sweetness. They have an oily mouth feel that can remind [one] of chicken soup. Their fragrance can be more complex than tea made from young plantations. Old-growth tea can generally be brewed more times than young plantations tea.

These differences can also be noticed when comparing young and older tea plantations. A lot of great tea comes from 50+ year-old tea plantations.

It’s important to keep in mind that the age of the trees is only one factor among others that makes good tea. The agricultural techniques and the location of the gardens (including altitude, soil, environment…) will have a large impact on the taste of tea. Some young plantations produce excellent tea, while some old tea gardens are not highly praised.

To what extent can tea tree ages be identified?

Following some heated debates on the internet, I have looked into the questions. Interestingly, I have found published scientific articles that discuss the age of specific trees. At best, the circumference of the trunks is measured, and this is only loosely correlated to the age of the tree. According to farmers and experts I interviewed, growth rate of the trunk varies widely, depending on soil fertility and genetics. In some cases, we can know the age of the tea gardens from historical records, but not the age of specific trees.

The tree ring counting method does not seem to be used in the case of the tea trees.

Some vendors use the age of the trees as a selling point, but I would rather recommend using the size of the trees, which is easier to confirm.

Farmerleaf tea can be purchased here.