Establishing a few community‐based plant clinics in Nicaragua led to a series of innovations in plant health service delivery. A grassroots experiment became a nationwide initiative involving local service providers, universities, research institutions and diagnostic laboratories. This led to the creation of a ‘National Plant Health System’ offering regular advice to farmers. The innovations were driven by a momentum for change, committed individuals, joint learning and flexibility in programme management. External facilitation encouraged experimentation and bolstered growth of new alliances. The development of the national plant health system was constrained by existing work cultures that limit the scope of individual and institutional innovations.