In the 2024/25 season, the Kenya Tea Development Agency told its roughly 600,000 smallholder growers that their bonus was falling, in some factories by close to 20 shillings on every kilogram of green leaf. The agency's own explanation split the blame three ways: weak demand, a glut of unsold stock, and one line that had nothing to do with tea at all. The Kenyan shilling had strengthened, from an average of 144 to the US dollar in 2024 to about 129 in 2025. KTDA's national chairman, Chege Kirundi, put a number on that single line item: the currency move alone cost about 15 shillings on every dollar of tea revenue.

That is the part of a grower's income that has nothing to do with rain, plucking, or the auction floor. Tea is grown, plucked, and processed for wages paid in the grower's own currency. It is then sold, in most of the world's major markets, against the US dollar. Whatever happens to that exchange rate between the two sides of the transaction lands, in full, on the grower's income, and it can do so in either direction, for reasons that have nothing to do with how good the harvest was.

A dollar auction was built to solve a different problem

The Mombasa auction, the largest tea sale in the world, has conducted every trade in US dollars since October 1992, by Kenyan government policy. The reason was not to protect Kenyan growers from their own currency. It was to protect the sale itself from several currencies at once: Mombasa is the only auction that trades tea from more than one country, and Uganda, Tanzania, Rwanda, Burundi, Malawi, and several others sell through it alongside Kenya. A dollar-only sale gave every buyer and every origin one stable unit to bid in, which is why the switch is remembered as having "obviated any devaluation in local rates and ensures rapid payment in a stable currency."

That fix worked. It also did nothing to remove currency risk from the transaction, it only moved it downstream. A dollar auction price is fixed the moment the hammer falls. What is not fixed is the rate at which the Kenya Tea Development Agency later converts those dollars into shillings to pay the roughly 600,000 smallholders whose green leaf it processes. A 2014 academic study of exactly this problem, published in the Research Journal of Finance and Accounting, documented the mechanism: export earnings are earned in dollars and translated to shillings later, and the gap between those two moments is where the exposure sits. Nothing about the 2024/25 season was a one-off design flaw. It is how the system has always worked, and it simply had a bad year.

What a 10 percent currency move actually cost

The currency piece of that season is specific enough to isolate from everything else that went wrong. The shilling's move from 144 to 129 to the dollar, about a 10 percent appreciation, was itself worth close to 15 shillings for each dollar of export revenue, by KTDA's own account. That is a number the agency arrived at by holding the auction price and the shipped volume still and asking what the exchange rate alone had done to the proceeds, precisely the isolation this piece is making. It was not the season's only problem. Weak demand, a supply glut, and a bruising regional payout gap between factories did their own damage on top of it and turned a bad year into a governance argument. But the currency line is the one that would have bitten even in an otherwise ordinary season, on tea that nobody grew, plucked, or sold any differently than the year before. None of those farmers changed how they worked. The exchange rate changed underneath them.

India runs the same lever in the other direction

Indian tea is not sold at Mombasa's dollar auction. Kolkata, Guwahati, and the country's other centres price every lot in rupees, which moves the currency exposure to an earlier point in the chain: instead of showing up when a cooperative converts dollars back into local pay, it shows up in what a foreign buyer is willing to bid in the first place.

In 2025 the rupee weakened against the dollar, and Indian tea's export value hit a record 8,488.43 crore rupees, up 18.4 percent on the year, and the average export price crossed 300 rupees a kilogram for the first time, an 8.1 percent rise. Read in dollars, the same tea moved from $3.34 a kilogram to $3.40, a rise so small it would barely register as a headline. The Indian grower and exporter banked a record year in rupees; the foreign buyer paid, in the currency that actually leaves their account, almost the same price as the year before. Kenya's growers lived through the currency squeezing their income at the point their agency converted dollars home. India's growers lived through the same lever pulling the other way, built into the price itself, at the point of sale.

The gain did not erase the industry's older problem. The Indian Tea Association has pointed out that auction prices have grown by only around 4 percent a year over the past decade on a compound basis, while input costs such as coal, gas, and sulphur have risen 9 to 15 percent a year over the same stretch. Wages make up close to 60 percent of the cost of growing and processing tea in Assam, and electricity alone runs to roughly 10 to 11 rupees for every kilogram made, according to the Hindi-language outlet Kisan India. A weaker rupee helped the export ledger. It did nothing to the rupee cost of a kilowatt-hour or a day's wage, because both of those are set and paid at home, regardless of which way the dollar moves.

Sri Lanka shows the same rule cuts both ways

Sri Lanka's Colombo auction, the oldest of the world's major tea sales still running (its history is told in The Tea Auctions), settles in rupees too, and in 2024 it lived through the mirror image of India's story. The Sri Lankan rupee appreciated by around 10 percent against the dollar in the second half of that year. By the fourth quarter, Sri Lanka's own trade press reported, tea pricing in rupee terms had gone soft even as the same tea's dollar-equivalent value rose, an outcome the industry attributed directly to the strengthening currency. The full-year national average price still edged up in nominal rupee terms, by close to 54 rupees per kilogram, but that gain arrived at the same time the currency was working against it, not because of it. Sri Lanka's growers, like Kenya's, found that a stronger local currency was not obviously good news the year it happened.

The bill that never moves with the exchange rate

What ties these three cases together is not the direction of any one currency. It is that the cost side of a tea garden's ledger is fixed in the grower's own money no matter what the export price does. A plucker's daily wage, a factory's diesel and electricity bill, and a season's fertiliser order are all quoted and paid in shillings, rupees, or the local unit of account, set by local labour markets and local energy prices. The revenue side, whether it arrives in dollars at Mombasa or in rupees that a foreign buyer converted to bid, is the only part of the ledger that moves with a foreign exchange rate. A currency swing therefore lands entirely on the margin between the two, which is exactly why it can swamp a season's income more thoroughly than a below-average harvest would.

That asymmetry is also why hedging the risk away is harder in practice than it sounds. Currency markets do offer forward contracts that can lock in an exchange rate months ahead, a tool many multinational commodity traders use routinely. What the 2014 study of Kenyan smallholder factories found is a structural mismatch: the exposure sits with tens of thousands of individual growers, aggregated through cooperative factories that sell in bulk and only later divide the proceeds, which is a poor fit for an instrument priced for a single counterparty with a known dollar exposure and the credit standing to post it. No Kenyan or Indian smallholder cooperative in the reporting behind this piece was described as running a currency hedging programme for its farmer payouts. The exchange rate simply passes through.

What this means for reading next season's bonus number

A garden's income in any given year is the sum of three things that move independently: how much it grew, what the auction paid for it, and what the exchange rate did to the proceeds by the time they reached the grower. The Kenyan and Sri Lankan cases in 2024 and 2025 show a stronger local currency taking money off the table even in a season when the crop itself was unremarkable. The Indian case in the same window shows the same lever adding money to the table for growers whose crop and effort had not obviously changed either. A reader watching a country's tea bonus rise or fall from one season to the next is watching at least two different stories layered on top of each other, and the exchange rate, not the weather, is often the one moving faster.