Increasing urban tree cover has multiple health benefits, one of the most dramatic of which is reduced heat-health risks. Trees reduce urban heat islands and thereby reduce heat hazard intensity and thus adverse health effects of heat exposure. Tree canopy cover of at least 30% to 40% is optimal for health protection, and simulation studies have found that increasing tree canopy cover to this level results in reductions of hundreds of heat-attributable premature deaths annually in medium to large cities in Europe and the US. There are few reports of the implementation time or cost of large scale tree planting campaigns. Young trees generally require decades to mature and other health protections should be considered in tandem with tree planting, particularly in highly impacted communities, in order to provide immediate benefits while tree canopy interventions reach their maximum impact over several decades.