The tea gardens of Darjeeling, in the foothills of the Himalayas, produced significantly less than 1 percent of India's 2.6 billion pound output last year. Yet Darjeelings are considered the "Champagne of teas," the finest in the country and some of the most exquisite and sought-after in the world.

The harvesting season in Darjeeling runs from mid-March through November, as the tea bushes gradually progress through a quartet of distinct seasons known as "flushes." The tea is often sold not only by single estate (like wine) but also by flush.

The first flush is keenly anticipated, and the second has obtained near-cult status. Yet many of India's top tea experts point to another as their personal favorite, autumn flush. Those teas, though, remain largely unknown and, alas, nearly impossible to find in tea shops.

A Primer On Flushes

Darjeeling traditionally produces black teas: The freshly plucked leaves are withered overnight, rolled and fermented (or oxidized) before being fired. The teas have an unrivaled metallic brightness in the cup, fragrant aromas, and flavors that hint of apricots, peaches, muscat grapes and toasty nuts.

But each flush offers a distinctive variation on these characteristic traits.

First flush teas, made as new leaves, stimulated by the first moisture after a winter of dormancy, start appearing on the bushes. Yellowish-green in the cup and light on the palate, they have an appealing spring freshness to them, with a hint of astringency that gives the tea a pleasing crispness.

Darjeeling's renown muscatel flavor — perhaps best described as a musky spice with sweet notes — is at its most pronounced during the second (or summer) flush. They days are warmer and the tea leaves slightly bigger. The brilliant golden-coppery liquor offers rounder, deeper flavors.

The monsoon arrives in Darjeeling sometime in June, and during the wet months that follow, the bushes produce abundantly. But the leaves are larger and coarser, and the damp weather complicates the withering and fermentation steps, making it difficult to turn out fine teas. Despite their romantic name, the monsoon flush is generally consigned to blenders who will mix it with other, often lesser teas to give them flavor. (The lower-grade monsoon teas frequently end up in less expensive teabags, sometimes without even the Darjeeling name.)

Autumn flush — the last of the year — begins by the end of October, once the monsoon has withdrawn from the misty hills, the rains tapered off, and the temperatures begun to drop. The tea bushes reduce their output as they move toward hibernation. It is the shortest of the harvests, and lasts just 30 or so days.

"The liquor has a delicate yet sparkling character with a delightful flavor, distinct from both first flush and second flush with a round cup," says B.N. Mudgal, who managed for last few decades Jungpana, one of Darjeeling's most storied gardens. "The infused leaf has a coppery gold brightness with a sweet fresh nose." That color can run to bright amber, even burgundy.

A Favorite Of Discerning Palates

Less floral and delicate than the opening flushes, autumn flavors tend to be more deeply fruity, with notes of ripe grapes and berries. "This is the kind of tea where you can get body," says Girish Sarda. His family has run Nathmull's of Darjeeling, the hill station's finest tea store, since 1931.

Or, as Rishi Saria, of the high-elevation Gopaldhara Tea Estate, says, "a robust cup and solid cup."

Robust is relative, and is far from the strong breakfast teas of Assam and Kenya. Even at its boldest, Darjeeling is still generally drunk without milk, sugar or even lemon.

"If there is one word I would use to characterize these teas, it would be well-balanced," says Jai Kejriwal, whose family has owned Jungpana since acquiring it from the Nepalese royal Rana family in 1956. "The teas have no sharpness, bite or astringency that typifies first and second flush teas."

The rounded flavors and smoothness in the mouth, slightly sweet under notes, and mellowness make it the most readily palatable of all Darjeeling teas for Kolkata auctioneer Anindyo Choudhury, who tastes about a thousand different teas from Darjeeling each week.

Autumn is the personal favorite flush of many of India's most discerning tea tasters, including Choudhury and the celebrated tea master and blender Sanjay Kapur, who savors the complexities of the flush's flavor.

Elusive Taste

Yet the autumn flush rarely makes it beyond India's borders.

Among the top North America purveyors of fine teas that sell Darjeeling tea by estate and flush, neither Harney & Sons nor Tea Trekker offer any, while Upton Tea Imports has just a single autumn flush among the 26 Darjeelings it stocks. Even the world's finest tea shop, Mariage Frères of Paris, which carries over 100 different Darjeeling teas, offers just three from the autumn flush.

There is significantly less tea from this final harvesting period. With less quantity, only a limited amount makes it to public auction. Gardens generally sell their autumn flush privately to exporters and a few online retailers and tea boutiques.

But this is not the sole reason it is nearly impossible to find in shops. Buyers abroad are largely done for the year, and often distracted by the impending Christmas holidays. Most of the top stores do not bother to stock it.

That means that customers are rarely even aware of autumn options. In France, which has a long tradition of drinking fine teas, customers at such well-stocked stores as Mariage Frères keenly await the arrival of first and second flush teas, but often have little idea that there will be new Darjeeling offerings arriving late in the year.

Certainly they are missing out on the last offering from the tea bushes before they go into hibernation. "The sweetness, smoothness and balanced fruity and floral notes of the cup are in complete harmony," says Kejriwal. "It's almost as if the bush is looking forward to its rest, content after a season-long journey."

For those who can get autumn flush — unless you have access to a shop like Mariage Frères, the best place might be a specialist online retailer, such as Teabox — it is the perfect way to ease out the final months of the year and sustain oneself until the new spring teas are ready in March.

First flush, at least, is easier to find.

SeparatorTea Tuesdays is an occasional series exploring the science, history, culture and economics of this ancient brewed beverage.

Copyright 2016 NPR. To see more, visit