The number of original papers, reviews and perspectives within the area of phyto-nanotechnology is virtually exploding. The field is highly cross-disciplinary, as it typically embraces plant and soil science, environmental chemistry and bio-nanotechnology. It is a demanding task to span across these converging scientific disciplines, especially in cases without a strong tradition for collaboration. Hong et al. (2021) have recently provided a timely review on foliar application of engineered nanoparticles (NPs) in agriculture, which we believe clearly highlights this challenge. Phyto-nanotechnology certainly holds a range of promising perspectives in the green transition of agriculture towards more climate- and environmentally friendly crop production systems. However, the review by Hong et al. (2021) contains many claims not supported by the scientific literature. Moreover, it contains claims which contradict fundamental knowledge within plant physiology and biochemistry. Finally, there are several cases of poor and misleading referencing, where there is a marked discrepancy between the content of the cited paper and the statement it is supposed to support in the review. In this comment, we critically discuss the most important shortcomings found in the review, with a special focus on plant nutrition.