Over the past few millennia, tea crafters have developed myriad ways of drying and preserving the leaves to increase the shelf life of the finished tea. First, leaves were steamed and compressed, then dried and powdered, and today they are withered and fired, with each step removing more moisture. But any tea requires proper storage for the best flavor, no matter how well they’re preserved in crafting. Green teas are especially prone to losing flavor, since they don’t go through additional withering during the oxidation process.

So what is the best way to store tea leaves, in order to keep them as fresh as possible? In the simplest terms, tea leaves are best kept away from light, air, and moisture.

Effects of Oxygen

Most tea drinkers know that tea should be stored in airtight containers. As part of the crafting process, oxidation is strictly managed, but even finished tea leaves can continue to oxidize on the shelf. Over a long period of time, green tea leaves can turn brown and lose flavor through this slow, steady reaction with oxygen. Good quality tea canisters use a double lid to create an airtight seal, but air trapped in a nearly empty canister can have the same effect.

In addition, tea can absorb strong flavors from other things stored nearby. Subtle flavors can be overwhelmed by the aromas of spices, or even the smell of a wooden storage box. While an airtight container might mitigate this effect, teas should always be stored away from spices or coffee.

Effects of Light

t can be tempting to store beautiful tea leaves in glass jars, so they can be easily viewed and admired. But exposure to light has been shown to decrease the intensity of aromatic compounds in the leaf. While the mechanics of this process are not fully understood, it is generally thought to be a continuation of the oxidation process. Instead of transparent glass or plastic, we recommend metal or ceramic storage.

In addition, light shining on a glass jar builds heat around the tea leaves, which has been shown to cause degradation of catechins (one type of antioxidants) in the leaf. Prolonged exposure to heat also speeds oxidation, increasing the speed at which the leaves go stale. Some tea drinkers seek to avoid this issue by storing their teas in the fridge or freezer, but we typically don’t recommend this method. Any air trapped with the tea will condense, creating moisture: our next culprit.

Effects of Moisture

It probably comes as no surprise that moisture extracts flavor from dried tea leaves, since this is exactly how we prepare the familiar beverage. When the dry leaf becomes hydrated, water soluble flavor compounds are released. Therefore, the biggest factor in determining how long tea will stay fresh is the relative humidity of the environment. In humid parts of Asia, this can be a huge problem. Many teas are sold in vacuum sealed bags to avoid this effect during storage, but the compression of a vacuum seal can also cause leaf breakage, especially with long, twisted leaves.

In California, and much of North America, the lack of humidity is a tea hoarder’s dream. Green tea drinkers from Zhejiang have been known to buy Dragonwell in San Francisco late in the year, since the leaves keep better in the cooler weather. While the humidity in their homeland can render green tea stale and flavorless in less than six months, San Francisco’s relatively dry climate keeps our green teas tasting crisp and flavorful for at least a full year.

Exceptions to the Rules

These simple guidelines for keeping your tea fresh apply to almost any type of tea, whether light or dark. However, it’s important to note that while some teas (like green teas) are most prized when they are fresh off the plant, darker styles are often given some time to rest and mellow. At the opposite end of the spectrum, pu-erh teas actually require exposure to air and humidity for continued fermentation, and develop deeper, richer flavors when exposed to heat.

Finally, while these tips will help you keep your tea fresh for as long as possible, most teas will lose flavor over time no matter how they’re stored. We recommend always asking for the harvest date of lightly oxidized teas to make sure they were picked recently. And of course, the best way to get the most aroma, flavor, and antioxidant content from your teas is to drink them, rather than store them! Check out these easy brewing methods to make your daily cup a little quicker.

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