Global habitat degradation has prompted an urgent need to develop efficient restoration strategies that address the problem at the right spatial scale. Applied nucleation is a restoration technique used in terrestrial forests that offers the opportunity to increase the extent of restoration, minimising the resources needed. It starts with planting small tree patches (“tree islands”) in focal areas that set the trajectory for natural recovery, resulting in large-scale habitat restoration outcomes. This concept may provide a framework for restoration of marine forests, which are declining at unprecedented scales, but its applicability in this system has not been tested. We used the decline and 13-year restoration effort of crayweed (Phyllospora comosa) forests along 70km of coastline as a case study to demonstrate the feasibility and challenges associated with applied nucleation strategies in marine forests. Underwater tree islands generally established and spread through time, but site-specific factors (e.g. wave action, herbivory, benthic cover) influenced initial colonisation and may determine expansion rates and the resources needed to maintain the trajectory for recovery. Small-scale efforts can lead to broader-scale revegetation in marine habitats, suggesting applied nucleation strategies may help kelp forest management at scale.