This article presents a practice-led investigation by a cross-disciplinary team of artists and computer scientists into the potential for mobile and digital communications technologies to engage visitors to London's Hampstead Heath with the histories of its veteran urban trees. Focusing on the application of Internet of Things (IoT) technologies within the arboreal environment for the digital poetic walk, The Listening Wood, it considers the reciprocal impact of “tree time” on the development of “slow tech.”