What the research says about hemp clothing
Hemp is often described as the greener fiber. That is broadly supported by the research, but the details are more interesting than the slogan, and some of the numbers shared online go further than the evidence does.
Water is where hemp stands out
A 2025 scoping review in the Journal of Cannabis Research found that hemp used roughly 220 to 700 mm of water over a growing season, depending on climate, irrigation, management and variety. The same review points to one 2023 comparison that put hemp's water requirement about 38% lower than cotton's and its water footprint about 60% lower.
A German field trial published in Water in 2020 reported hemp producing about 2.4 kg of dry matter per cubic metre of water, against 0.4 kg listed for cotton. That is about six times as much, but the result comes from one extremely dry year at one site, so it should not be treated as a universal figure.
The evidence is still growing
The 2025 review included only 17 studies and called for research across more regions and varieties. These studies also look at growing the plant. Spinning, dyeing and finishing affect the footprint of a finished garment too, and they are not covered by these water figures.
The biggest step is wearing it longer
Fiber choice is only part of the picture. A life cycle study posted on SSRN by Wiedemann and colleagues concluded that keeping garments in use for longer, and avoiding unnecessary purchases, does more to reduce impact than simply switching fibers. That is good news for a strong fiber like hemp, as long as the piece is well made and you keep wearing it.
Sources
- Gokool S, Mantel S, Clulow A, Kunz R, Palmer A. An assessment of the water use of hemp: a scoping review and bibliometric analysis. Journal of Cannabis Research, 2025.
- Wise et al. Comparative study of water requirements and water footprints of fibre crops hemp and cotton. Journal of Agrometeorology, 2023.
- Drastig K and colleagues. Field study of water productivity in industrial hemp. Water, 2020.
- Wiedemann SG, Clarke SJ, Nguyen QV, Cheah ZX, Simmons A. Strategies to Reduce Environmental Impacts from Textiles: Extending Clothing Wear Life Compared to Fibre Displacement Assessed Using Consequential LCA. SSRN.