THE DARJEELING CLONAL
HANDBOOK

TABLE OF CONTENTS

Introduction: The Cultivar Revolution in Darjeeling

When the first Chinese seed stock arrived in Darjeeling in the 1850s, the region's planters had little choice but to plant what they were given. By the early twentieth century, estates had begun selecting and propagating individual bushes that showed superior yield or quality. But the modern era of Darjeeling tea—the era in which a buyer can specify AV2 from a particular estate's south-facing block, or pay a premium for first-flush P312—began in earnest in the 1960s, when the Tocklai Experimental Station and later the Darjeeling Research Centre released numbered clonal cultivars selected for agronomic and organoleptic performance.

Today more than forty commercial clones are planted across Darjeeling's eighty-seven gardens, and the cultivar is as important to the cup as the flush, the altitude and the maker's skill. AV2 delivers the floral top notes that define a classic first flush; B157 offers muscatel depth in second flush; P312 combines yield with elegance; T78 thrives at altitude where other clones struggle. Yet cultivar data remains stubbornly opaque. Estate websites rarely disclose their plantings; auction catalogues seldom name the clone; and most published guides recycle the same half-dozen names.

This handbook breaks that silence. It is written for three audiences: the estate manager deciding what to replant after a frost, the specialty buyer building a single-estate program, and the serious enthusiast who wants to understand why one garden's first flush tastes brighter than another's. We profile the twenty-five most commercially significant clones, map their distribution across major estates, explain their agronomic trade-offs, decode their flavour signatures, and quantify—where the data permits—the price premiums they command.

The intelligence here is drawn from estate interviews, research bulletins, planting records, auction data and two decades of cupping notes. Where figures are uncertain or contested, we say so. Where a clone's reputation exceeds its planted acreage, we note that too. This is not tea folklore; it is the clearest picture yet published of how Darjeeling's cultivar landscape actually works.

1. The Clonal Selection Programme: History and Methodology

Darjeeling's transition from seedling populations to clonal monoculture did not happen overnight, and many gardens today remain a patchwork of old seedling sections, early estate selections, and modern Tocklai or DRC releases.

The Tocklai and DRC Selection Process

The Tocklai Experimental Station (now the Tocklai Tea Research Institute in Assam) began systematic clonal selection in the 1940s, evaluating thousands of individual bushes for yield, pest resistance, drought tolerance, and quality. Promising individuals were propagated vegetatively and planted in replicated trials. Only after ten to fifteen years of field evaluation—across multiple sites, elevations, and pruning cycles—was a clone assigned a number and released for commercial planting. The Darjeeling Research Centre, established in the 1960s, applied the same rigour to Camellia sinensis var. sinensis populations at altitude, selecting for cold hardiness and the delicate flavour profiles the region demanded.

A clone earns its number on the basis of agronomic performance (yield per hectare, shoot density, pruning recovery, pest/disease resistance), biochemical markers (polyphenol content, amino acid profile, volatile precursors), and cup quality as assessed by a trained panel. Importantly, these three dimensions do not always align. A high-yielding clone may produce a plain cup; a low-yielding clone may command a premium. This tension—between the estate manager's spreadsheet and the cupper's scorecard—runs through the entire clonal story.

Estate Selections and Proprietary Clones

Alongside the official releases, many estates have propagated their own selections—sometimes from within their existing seedling populations, sometimes from Tocklai trial material before formal release. These estate selections are rarely documented in the public literature but can be locally significant. For example, Castleton's famed muscatel character owes as much to its proprietary selections (sometimes referred to informally as 'Castleton types') as to its better-known official clones. Buyers should always ask which clones or selections an estate actually plants, not which ones it lists on its website.

By 2026, roughly 60–70% of Darjeeling's planted area is clonal, with the remainder in seedling populations (especially in older, high-altitude sections where replanting is slow and costly). The shift toward clones accelerated after the severe frosts of 2011 and 2014, which killed many old seedling bushes and prompted widespread replanting with proven cold-hardy clones like AV2, P312, and T78.

2. Understanding Flush Timing, Elevation, and Clonal Interaction

A clone's performance is never absolute; it is always a function of elevation, flush timing, pruning cycle, and processing skill. The same clone planted at 1,200 metres and at 1,800 metres will yield different cups, and the same clone picked in March versus May will express different volatile profiles.

Elevation Bands and Clonal Suitability

Darjeeling's gardens span roughly 600 metres to 2,100 metres above sea level, and not all clones thrive at all elevations. Low-elevation clones (600–1,200 m) tend to emphasise yield and vigour; they include B157, TV1, and some TV-series Assam hybrids used in rain-fed sections. Mid-elevation clones (1,200–1,600 m)—the heart of Darjeeling—include AV2, P312, B777, and China hybrid types; these balance yield with quality and are the backbone of first- and second-flush production. High-elevation clones (1,600–2,100 m) must tolerate late spring cold, shorter growing seasons, and intense UV; T78, AV2 (again), and some seedling populations dominate here.

Flush Timing and Volatile Expression

Darjeeling's flush calendar divides the year into first flush (March–April), second flush (May–June), monsoon flush (July–September), and autumnal flush (October–November). First flush is prized for its bright, green-floral character; second flush for muscatel sweetness and complexity. Clones differ in their bud-break timing—early clones like TV1 can be picked in late February at low elevation, while late clones like T78 may not break until mid-April at altitude—and in their volatile precursor profiles. AV2 accumulates linalool and geraniol precursors during slow spring growth, yielding intense floral notes in first flush. B157 develops terpene alcohols and amino acids (especially theanine) in the warmer May weather, contributing to its characteristic muscatel depth.

Processing also interacts with clone. Orthodox manufacture—withering, rolling, oxidation—allows a clone's native volatile profile to express fully. CTC processing, still used for a small fraction of lower-elevation Darjeeling production, erases most clonal distinctions. This guide assumes orthodox processing throughout.

3. Agronomic Performance Metrics: Yield, Vigour, and Pest Resistance

For the estate manager, a clone's value is measured first in kilograms per hectare, recovery from pruning, susceptibility to blister blight and red spider mite, and longevity of the field. Flavour is secondary if the clone cannot pay its way.

Yield and Economic Viability

Darjeeling yields are among the lowest in the world—typically 400–800 kg of made tea per hectare per year, compared to 1,500–2,500 kg/ha in Assam or Kenya. High-altitude sections may yield as little as 300 kg/ha. Within this constrained range, clonal choice still matters. High-yielding clones like TV1, TV18, and B157 can reach 800–1,000 kg/ha in favourable mid-elevation sites, while low-yielding quality clones like AV2 at altitude or China hybrid seedling sections may deliver only 300–500 kg/ha. The estate must decide: does a 20% yield penalty justify a 30% price premium at auction? The answer depends on the estate's reputation, buyer relationships, and cost structure.

Pest and Disease Resistance

Blister blight (Exobasidium vexans) and red spider mite (Oligonychus coffeae) are the two most economically damaging pests in Darjeeling, and clonal resistance varies significantly. TV-series clones (TV1, TV9, TV18) were selected in part for blister-blight tolerance and perform well in monsoon conditions. AV2 and China hybrid types are more susceptible and require careful canopy management and, in conventional estates, fungicide application. B157 shows moderate resistance. Many estates have reduced pesticide use since 2015 (driven by organic and Fairtrade certification), making clone choice even more important: a susceptible clone in an organic block can lose 30–50% of its flush to blight in a wet year.

Pruning cycle also matters. Most Darjeeling clones are pruned on a three- to five-year cycle (compared to annual pruning in high-yield regions). Fast-recovery clones like P312 and TV1 resume full yield within 18–24 months post-prune; slower clones like T78 may take three years, reducing their lifetime economic return.

4. Biochemical and Sensory Foundations: What Makes a Clone Taste Different

Flavour in tea is the emergent property of volatile aroma compounds, non-volatile taste-active molecules (polyphenols, amino acids, alkaloids), and the sensory interactions among them. Clones differ in the genetic regulation of secondary metabolism—the biochemical pathways that produce these compounds—and thus in their potential flavour profiles.

Volatile Aroma Compounds

First-flush Darjeeling is famous for its floral, green, and citrus notes, derived largely from linalool (floral, coriander-like), geraniol (rose-like), linalool oxides (sweet floral), and hexanal / hexenals (green, grassy). These volatiles are synthesised during the slow spring flush and released or transformed during withering and oxidation. AV2 is a high-linalool clone; in first flush, its dry leaf can contain 200–400 µg/g linalool (compared to 50–150 µg/g in lower-quality clones), which translates directly into a more pronounced floral top note.

Second-flush muscatel character is less well understood but is thought to involve terpene alcohols, fatty-acid derivatives, and Maillard-related compounds formed during oxidation and drying. B157 develops higher levels of certain terpene precursors and combines them with elevated free amino acids (especially theanine and glutamate), creating a sweet, fruity, mouth-coating profile. The term 'muscatel' is subjective, but trained panels consistently score B157 second-flush lots higher for fruity sweetness and complexity than TV-series or China hybrid lots from the same estate.

Polyphenols, Amino Acids, and Mouthfeel

Total polyphenol content in Darjeeling clones ranges from 18% to 28% of dry weight (lower than Assam, which runs 25–35%). China types and AV2 tend toward the lower end, contributing to a lighter, less astringent cup; TV hybrids and B157 are higher, giving more body and tannin structure. Catechin composition also varies: AV2 has a higher ratio of simple catechins (epicatechin, epigallocatechin) to the galloylated forms (EGCG, ECG), which correlates with reduced bitterness and a smoother mouthfeel. Theanine, the amino acid responsible for umami and sweetness, is elevated in B157 and P312, especially in second flush.

• High linalool / geraniol: floral, bright, 'classic first flush' (AV2, P312)
• High terpene alcohols + theanine: muscatel, sweet, complex (B157, B777)
• Balanced catechins, lower astringency: smooth mouthfeel (AV2, China hybrid)
• Higher total polyphenols: body, structure, longer brew tolerance (TV1, TV18, B157)

Processing skill remains paramount: a skilled maker can coax maximum volatile expression from AV2, while poor withering or over-oxidation will flatten even the best clone's profile. But given equal processing, clonal differences are real, measurable, and sensorially significant.