One of the most transformative events in the Earth's history was the transition of life from aquatic environments to the land. This not only changed the subsequent evolutionary history of these newly-terrestrial organisms, but also reshaped the global environment: the land, the oceans and the atmosphere (Fig. 1). In order to understand this process, scientists cannot look at single aspects in isolation. Accordingly, in 2010 a multidisciplinary symposium took place to act as a forum for scientists from numerous biological and physical disciplines to exchange ideas and to determine the extent of our current knowledge (Coates et al., 2011). Six years on, the 38th New Phytologist Symposium ‘Colonization of the terrestrial environment 2016’ (www.newphytologist.org/symposia/38) brought together many of the same scientists, plus plenty of newcomers, to reflect on how far we have come, and what still remains to be answered.