Kava roots: an underground treasure

2021-02-20 · 5 min read

By the kava.fyi editorial team · Last updated: 20 February 2021

The plant that does not propagate from seed

Kava, also known by local names such as awa, yaqona or sakau, and scientifically as Piper methysticum, belongs to the pepper family. A mature shrub can reach as much as four and a half metres in height and has distinctive, large, heart-shaped leaves. Although the plant produces both male and female flowers, in practice it almost never sets seed capable of germinating. That is why kava is propagated almost exclusively vegetatively, from stem sections separated from the parent plant during root harvest.

In practice, this means new shrubs are genetically identical to the plant they come from. Cuttings are usually fifteen to twenty centimetres long and are cut from low or young stems. Once planted, cultivation takes three to five years before the roots develop properties that justify harvesting. That is a long cycle for a crop plant, far longer than for most vegetables or grains, and one reason why the quality and origin of the root matter so much for the final product.

Soil, shade and rain: the conditions kava needs

Kava shrubs grow only in well-drained, loose soils that give the roots constant access to air. Growth is favoured by light shade, temperatures between 21 and 35 degrees Celsius, relative humidity reaching as high as one hundred per cent, and annual rainfall above 2,000 millimetres. These are conditions typical of humid, mountainous tropical regions of the Pacific islands: Vanuatu, Fiji, Tonga, Samoa, Micronesia, French Polynesia and Hawaii, where the plant has been cultivated for more than three thousand years and is deeply woven into the medicine and social rites of these cultures.

In many of these places, growing kava remains the domain of small, independent family farms, for whom it is both a source of livelihood and of standing within the local community. The work is largely manual, and plantations are often established on hard-to-reach, highland terrain, where soil and climate conditions are most favourable.

Why the root is the most valuable part

Choosing the root as the raw material is not arbitrary. Research on kava chemotypes, including work by Siméoni and Lebot published in the journal Biochemical Systematics and Ecology, shows that the content and proportions of kavalactones, the plant's main active compounds, vary clearly depending on the plant part, cultivar and age. Different kavalactones dominate in the leaves than in the root: it is in the root and rhizome that the concentration of kavain and methysticin is highest, and in the lateral roots it can be two to three times higher than in the rhizome alone. A more recent study, published in 2025 and covering kava grown on the islands of Taveuni, Qamea and Rabi in Fiji, confirms that the kavalactone profile depends strongly on the specific cultivar and growing location, which has a direct bearing on the quality and predictability of the raw material's effects.

Kava's characteristic effects come mainly from six main kavalactones: desmethoxyyangonin, dihydrokavain, yangonin, kavain, dihydromethysticin and methysticin, which together usually make up around 96 per cent of all the kavalactones present in the plant. The rest consists of a dozen or so minor compounds from the same chemical group, plus small amounts of other substances, including flavokavains. The proportions among these six compounds determine what is known as a cultivar's chemotype, and it is this that largely determines whether a given kava acts more relaxing or more conversation-stimulating. You can find more on how this works in the article on kavalactones and the piece on how kava works.

What happens after harvest

Once dug up, the roots are cleared of fine rootlets, weighed, soaked for around ten minutes, and then washed for a further half hour. The cleaned roots are laid out on special racks and air-dried for four to six hours, after which they go through further, controlled drying that usually takes about a day. The dried roots are then broken down, and their moisture content is checked: if it exceeds the acceptable level, the material goes back to drying. Only once the raw material is fully dry does it go to milling, which produces the powder ready for preparing the drink.

This multi-stage process has a direct bearing on kava's pharmacology. A clinical study of kavalactone pharmacokinetics after oral dosing of a standardised extract found that different kavalactones reach maximum blood concentration within one to three hours of intake, with individual compounds differing from each other in their rates of absorption and elimination. That is one reason why the quality of drying and storing the root matters not just for taste, but for how predictable the finished drink's effects are.

Why the origin of the root matters

If predictable, traditional kava effects matter to you, it is worth knowing where the raw material comes from and which part of the plant it was made from. Cultivars classed as noble have a higher share of kavain relative to methysticin and dihydromethysticin, which is associated with a gentler effect profile, while two-day (tudei) cultivars have a different chemical makeup and are traditionally treated with more caution because of their longer-lasting effect. This distinction is not just a marketing point but a real chemical difference confirmed by chemotype analyses. If you want to know how to prepare a drink from root prepared this way, in keeping with tradition, see also the piece on preparing kava and on the differences between powder and instant.

Kava root is sometimes called an underground treasure for good reason: it is there, over several years of slow growth, that all the chemical complexity accumulates that determines the character of a plant prized in the Pacific islands for thousands of years. The longer and more carefully cultivation is carried out, the more predictable and even the root's composition becomes, and it is precisely that patience, spread over years, rather than any single agricultural technique, that sets good-quality raw material apart from a random batch.