蜜芽传媒

A listener wants to know whether a garden product can really make your grass six times greener. Can you put a numeric value on how green a colour is? Is it possible to tell when something is six times greener than baseline with the human eye, and is there a maximum green to which all lawns should aspire? Tim Harford explores the greenness of grass.

First broadcast on More or Less, 20 May 2018.