When the Dutch botanist Pieter Korthals described kratom for European science in the late 1830s, he noted where he found it: on riverbanks in Borneo. Nearly two centuries later, thatâs still where much of the worldâs supply starts. Most of it grows along the upper Kapuas River in Indonesiaâs West Kalimantan province, in a regency called Kapuas Hulu.
Kapuas Hulu sits in the middle of the island, bordering Malaysian Sarawak, and covers about 31,000 square kilometers, roughly a fifth of the province. For most of the last century its farming economy ran on rubber.
A rubber economy that stopped paying
Rubber arrived in Kapuas Hulu in the early 1900s with Dutch missionaries, and Dayak farming communities folded it into their rotation of rice fields and forest gardens. At its best it carried household finances.Land-use research in the regency found rubber made up 30 to 80% of household income when prices peaked in 2011 and 2012.
Then prices fell and stayed unpredictable. Rubber is tapped by hand, daily, and when the price per kilo drops far enough the math stops working. Along the upper Kapuas, people started looking for something else to grow.
Why kratom fit
It was already there. Mitragyna speciosa is native to the regionâs wet lowlands and river margins, and itâs harvested for its leaves, so the same tree can be picked again and again without being cut down. A study of Kapuas Hulu kratom farmers describes rubber tappers and rice farmers converting to kratom, planting it in gardens and home yards because it paid better. By 2018, the regencyâs plantation office was recording kratom acreage close to the area under rubber.
For the land itself, thatâs a quieter kind of boom than most. A native tree grown in mixed gardens and along rivers is a very different land-use story from oil palm, which typically means clearing for monoculture. Indonesiaâs public broadcaster RRI has reported on local officials presenting kratom as both an ecological asset and a source of steady work, with planting, harvesting, and processing all done by local farmers.
From leaf to powder
Harvesting is manual. Farmers strip mature leaves by hand, and what happens next depends on the buyer. Some leaf is dried straight away; some is fermented first, which shifts its color and aroma. Larger producers in the region have invested in milling machines that grind dried leaf into powder.
That last step became mandatory for export in 2024. Indonesiaâs Ministry of Trade issued two regulations setting the terms for kratom exports, including standards for microbial contamination, heavy metals, and mixing with other leaves. Under those rules, kratom can leave the country only as crumbs or powder finer than 600 microns, so whole leaf stays home. As recently as late 2025, government agencies were still arguing over parts of the framework.
Why Indonesia tightened the rules
The 2024 regulations came out of an internal meeting led by then-President Joko Widodo, and the reasoning was partly economic. Officials wanted more of kratomâs value to stay in Indonesia, which means exporting finished powder instead of raw leaf for someone else to mill.
The framework still isnât settled. At a coordination meeting in Jakarta in late 2025, Deputy Coordinating Minister Otto Hasibuan called kratom a crop with strong economic potential and weak legal clarity, and pushed agencies to agree on a single approach. For farmers upriver, unsettled rules are one more variable in a crop they took up because it paid better than rubber.
Where the color names come from
Drying choices made in Kapuas Hulu are also where most of the labels on US kratom packaging begin. The red, green, and white names sold in the US describe the leafâs maturity at harvest and how it was dried or fermented, more than any difference in the tree. Sun-drying and fermentation push the leaf toward red; shade-drying indoors keeps it greener. So the color on the bag is, in a sense, a record of a decision someone made on a drying rack near the river.
What that means at the other end
For a buyer in the US, the result is a supply chain with more checkpoints than it had five years ago, and more distance between the farmer and the bag. Export standards cover contaminants at the border. They donât tell you which farm the leaf came from, how it was dried, or how it was stored after it landed.
A batch lab report fills that gap. If you shop for kratom online, the sellers worth buying from publish a report for each batch, so you can see what was tested after the leaf arrived, on top of what was required before it left.
Somewhere upriver from Putussibau, the regency capital, someone is stripping leaves from a tree that was growing there before the rubber. Itâs worth knowing who.
Statements in this article have not been evaluated by the Food and Drug Administration. These products are not intended to diagnose, treat, cure, or prevent any disease.
