The GROW Observatory (GROW) will create a sustainable citizen platform and community to generate, share and utilise information on land, soil and water resource at a resolution hitherto not previously considered. The vision is to underpin smart and sustainable custodianship of land and soil, whilst meeting the demands of food production, and to answer a long-standing challenge for space science, namely the validation of soil moisture detection from satellites. GROW is highly innovative project leveraging and combining low cost consumer sensing technology, a simple soil test and a large user base of growers and plant enthusiasts to contribute individual soil and land data. It is designed to engage primarily individual growers and small-scale farmers across Europe, and to enable them to develop new wisdom and innovative practices through the collective power of shared and open data and knowledge. Citizens contributing data will gain access to the first single-source comprehensive crop and watering advice service for individual and small-scale growers incorporating scientific and crowdsourced information. Moreover, they will develop ‘campaigns’ (coordinated sampling operations) around local needs and issues, to underpin smarter decision-making and implementation of policy objectives. GROW will actively identify and enable new and credible social and business innovation processes, creating potential new services, applications and markets. The outcome will be a central hub of open knowledge and data created and maintained by growers that will be of value to the citizens themselves as well as specialist communities in science, policy and industry. The GROW partnership will connect and scale to globally dispersed communities linked through digital and social platforms, and a wide range of additional citizen associations and NGOs in sustainable agriculture, gardening, food democracy and land management.